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Xerox University Microfilms
300 North Z e e b Road
Ann Arbor, M ichigan 46106
Tuck, Irma Evelyn, 19121942
A study of the pinene formaldehyde
New York, 1942.
4p.l.,74 typewritten leaves,
Thesis (Ph.D.) - New York university,
Graduate school, 1942.
Bibliography: p.72-74.
Xerox University Microfilms,
t'KU Lisl
Ann Arbor, Michigan 48106
iTrrAnj of
Irma E^ Tuck, B.S., M.S.
Submitted in partial fulfillment of the requirements for the
degree of Doctor of Philosophy at New York University.
To Professor John J. Ritter who suggested the
problem and whose vision, originality
understanding contributed materially to its
successful completion, the author expresses
her sincere appreciation.
\ n e - i ri 3
my mother and my husband
Pinene Rearrangement to camphane and
fenchene compounds
Borneol, camphene rearrangement
Wagner Rearrangement
Nametkin Rearrangement
Hydration Studies of pinene in mineral
and organic acids
Review of previously reported work on
formaldehyde and certain terpenes
The Prins mechanism for formaldehyde
Evaluation of the Prina mechanism as
applied to pinene
10 a
Products obtained in the present investigation
Isolation and Identification of a new solid
Oxidation of solid ether
The structure of homoplneol
Isomerization of homoplneol to an aromatic
Identification of the aromatic hydrocarbon
as 1,2 dimethyl Isopropyl benzene
The condensation of formaldehyde or its trimer, trioxymethylene (paraformaldehyde) with unsaturated compounds has
been recorded in the literature at scattered Intervals.
recent years interest has been considerably renewed because
the condensation affords a simple, direct means of converting
defines in cracked petroleum distillate to conjugated dienes
through the 1, 3 glycols or their methylene ethers
("1, 3 dioxanes”)1 .
Probably the first record of the course of reaction was
formulated by Lipp8 and Ladenburg® in two different ways.
Investigations of isomerism and structure amongst certain
nitrogen bases led the former to conclude that the addition
of formaldehyde took place as follows:
Ladenburg maintained that the reaction took place as follows:
Only in the case of alpha picoline, he reported that the
reaction apparently prooeeded as previously suggested by Lipp*
It should be pointed out that the two compounds are not quite
In one case we are dealing with a partially
.reduced nitrogen substituted methyl plcollne which probably
reacts as a simple olefine*
In the other case we are dealing
with alpha methyl plcoline whose reactivity may be modified
by the aromatic nature of the compound*
Homoplneol obtained by Kriewlts* in the condensation
of alpha pinene with paraformaldehyde, appears to have been
the first Instance of the formation of an allyl alcohol by this
simple and practical method*
This reaction has been extended
to the synthesis of other terpene alcohols by subsequent
investigators* Genvresse in 1904 reported condensations with
the sesqui terpenes caryophylene, clovene and cadinene*
Langlols several years later while investigating transformations
in the oamphene series, reported the condensation of camphene
with formaldehyde under conditions slightly different from the
previous workers*
In the presence of acetic acid as a solvent,
he obtained the ester of the 11 carbon alpha unsaturated primary
alcohol* ■ At about the same time Prins published a considerable
amount of material on the condensation of formaldehyde with
styrene, isosafrol, anethole, pinene, etc*
Prins showed also
that condensation occurs under various conditions in the
presence of a d d s and may lead to more than one type of product*
The efficiency of the reaction, however, was very good, in
all oases except the terpenes*
With the latter he obtained
only small yields of pure substances, 15$ being converted into
the unsaturated primary alcohols*
Recently in our laboratory Ritter and Freireich
studied this general type of condensation with dlisobutylene,
a simple aliphatic oleflne*
It has also been Shown by Tuck
that this type of condensation may be extended to tertiary
alcohols since they are capable of yielding defines under
the proper conditions in the course of the reaction*
The present research was undertaken to re-examine the
pinene formaldehyde condensation*
Frins and Krlewltz have
both reported a single product of this reaction, while the
present Investigator has observed that condensation in acetic
acid solution leads to at least two additional products*
yield obtained by Prins was 15$, which when compared with
70$-90$ obtained with oleflnic compounds which are not members
of the terpene series, led him to conclude that the terpene
primary alcohol underwent further reaction with more trioxymethylene and water*
However, he did not prove experimentally
the nature of these other products*
The present investigation
will therefore attempt to trace the course of the reaction,
illustrate the mechanism by which the products are formed,
identify the products and indicate how the yield may be
Pinene must be considered one of the most Important
members of the terpene hydrocarbons*
Because of its wide
distribution in nature and availability from natural sources,
its chemistry has been the subject of muoh early work*
Wagner, Baeyer, Wallach and others we may attribute the more
important oxidative, degradatlve and synthetic studies which
led to the clarification and elucidation of the structure of
the pinene molecule*
The accepted formulation is one containing
a bicycllc system and a single ethylenlc linkage*
The position of the double bond may vary within this
system in several ways, but the commonest isomers usually
obtained from natural sources are the alpha and beta forms*
Geometric isomerism by virtue of the double bond and the
position of the two rings, as well as optical Isomerism arising
from the existence of asymmetric carbon atoms, further aocount
for the mass of findings on the physical constants of so-called
pure specimens of the hydrocarbon*
both alpha and beta pinene have been isolated*
forms of
In nature,
beta pinene occurs in a majority of the oils in which alpha
pinene is present*
form of the former hydrooarbon is not common*
case of alpha pinene both
obtained from natural sources*
In the
forms are commonly
It is essential that the complex
nature of the stereo isomerism of pinene be constantly kept
in mind while considering the condensation of this molecule
with formaldehyde*
It is also significant to consider briefly the chemical
peculiarities so common to members of the terpene series*
a dicyclic terpene, pinene may undergo two different types
of reactions;
one Involving a scission of the cyclo butane
ring and the other involving molecular rearrangement followed
by conversion to other dlcycllc terpenes of different ring
The conventional graphic formula for pinene is:
To postulate any transformation to a mono cyclic terpene
necessitates considering a break of the four membered ring
at carbon number two and the Introduction of a second double
Isomerization of the two double bonds is possible and
therefore one can expect the formation of any number of
different compounds, the commonest of these being llmonene
-6 -
or dlpentene , terpinene of vhioh there are three different
forms, (2), (3), (4), and tex»pinolene (5)*
In considering the rearrangements within the pinene
molecule itself to produce other dlcyclic compounds with
different skeletons —
l*e», camphanes (6) and fenchanes(7).
it would be more convenient to formulate the pinene as
Addition of a compound which we may call HA would take place
in the usual manner to form
This compound will now undergo rearrangement so that group A
will change Its point of attachment from carbon No* 1 to
oarbon No* 2 and the 4 carbon ring will be opened and enlarged
to a five membered ring by satisfying the open valence at
carbon No* !•
Thus we produce:
Ring Isomerization In the terpene series has been the
subject of numerous investigations, chief of which are:
1* hydration of alpha pinene to borneol and fenchyl
2* transformation of alpha pinene to bornyl chloride
3* dehydration of isoborneol to camphene
4* conversion of camphene hydrochloride to isobomyl
Though the latter two reactions are not concerned directly
with pinene, the staxtlng material In the present Investigation,
they are worthy of a short discussion so as to complete the
considerations of outstanding chemical reactions In the
terpene series. In 1897 Wagner and Qodlewskl
prepared a
saturated hydrocarbon by the reduction of pinene dlbromlde.
They believed that It was a tricyclic compound and that a study
of Its reactions might lead to an explanation of the mechanism
of the rearrangement of pinene to camphene.
This Is the first
suggestion of the assumption of trlcyclene as an Intermediary
In these transformations. Ruzlcka
In 1918 applied this
concept to the borneol camphene rearrangement which he
designated the Wagner Rearrangement.
He therefore assumed
that the reaction proceeded through the formation of a cyclo
propane ring, thus producing the symmetrical saturated hydro­
carbon, trlcyclene, which might very well account for the
racemlzatlon accompanying the rearrangement.
we have:
The justification for the formation of any Intermediary
In such a rearrangement must come from a study of the reactions
of the Intermediary.
Trlcyclene had been Isolated and prepared
as stated previously and it was not long before Meerwein
and Van Emster
found a new method of producing it by the
action of the yellow oxide of mercury on camphor hydrazone*
A study of its transformations and reaction rates soon showed
that even a transitory existence could not be claimed for
it in the isoborneol camphene change*
In the presence of
33# sulphuric acid, isoborneol was converted quantitatively
to camphene, while trlcyclene was unchanged*
They noted also
that camphene could be esterified more rapidly than trlcyclene
with monochloracetlc acid under the same conditions*
the same time Lipp
At about
showed that whereas isoborneol gave
oamphene on heating with molten zinc chloride, trlcyclene was
stable and showed no reaction*
This remarkable stability and
chemical inactivity of trlcyclene, therefore discredited any
hypothesis which a ssumes its existence as an intermediary*
Furthermore, though
racemizatlon accompanies this change in
the presence of mineral acids and could be supported by the
symmetry of trlcyclene, in the presence of organic acids, acetic
and formic, optically active camphene results from optically
active isoborneol*
Meerwein and co-workers
X4 ^ X6f X©
soon modified their
concepts of the mechanism of this change as a result of a
series of studies on the effect of solvents on the velocity of
rearrangement of camphene hydrochloride to isobomyl chloride*
Since the velocity was relatively great in solvents of high
dielectric constant and conversely slow in solvents of low
-1 0 -
dielectric constant, they concluded that isomerization was
proceeded by ionization*
Further they observed that racemiz-
ation appeared,toq to be dependent upon the degree of ioniz­
ation since it followed the same course as the reaction
depending upon the dielectric constant of the solvent*
argued therefore that the whole change should be postulated
by assuming the formation of a uniplanar terpene ion and a
chloride ion and subsequent rearrangement of the cation*
To account for racemization, the terpene cation must be con­
sidered in equilibrium with
bornyl and isobornyl
chlorides as well as camphene hydrochloride*
and formation of any or both optical forms results from a
regrouping of the atoms of the terpene cation and is there­
fore directly dependent on the degree of dissociation possible
in a particular solvent.
It would thus seem that Meerwein*s
concept of rearrangement is not essentially different from
that originally advanced by Wagner but that the trend of the
former's work is governed by his interest in the correlation
-1 1 -
between velocity of rearrangement and dlelectrlo constants
of the media*
The net effect appears to be a postulation of
rearrangement within a terpene ion instead of rearrangement
within a terpene molecule*
The next real advance in the study of terpene rearrangements was presented by Nametkln and co-workers*
In 1923
Nametkin reported the preparation of 6-methyl camphor by a
series of common reactions*
Starting with fenchone, I, he
first prepared methyl fenchyl alcohol, II, by means of the
Grignar.d reaction using methyl iodide*
This tertiary alcohol
was then dehydrated with potassium acid sulfate in the same
manner in which bomeol is converted to camphene*
The product
resulting in this case was alpha methyl camphene, III*
latter was then rehydrated by the Bertram-Walbaum reaction to
6 methyl isoborneol, IV, which was oxidized by nitric acid to
6 methyl camphor, V*
Schematically the reactions involved were:
-1 2 -
The significant rearrangement first postulated for the
transformation of compounds III and IV after hydrolysis involved
the simple Wagner rearrangement.
It is illustrated as follows:
Wagner Ring Isomerization
6 Methylisoborneol
In 1927 Nametkin and Bruysova
published a paper in
which they demonstrated that the 6-methyl camphor previously
described and synthesized was actually 4-methyl camphor*
reducing the hydrazone of the camphor they obtained a hydro­
carbon which was designated now as 4-methyl camphane*
Nitration of this compound produced a secondary nitro compound
which on oxidation with permanganate gave the original ketone*
The absence of hydrogen at the 4 position was demonstrated
by the fact that no bromlnation of the methyl camphoric acid
-1 3 -
was possible and further that only anhydride formation resulted
from the treatment with bromine and phosphorous*
to account for the formation of 4-methyl Isoborneol rather than
6-methyl isoborneol in the series of reactions previously
illustrated, they proposed that the addition of water was
followed by an interchange of CHa and OH groups from carbons
Ho* 3 and 2*
After this shift, ring isomerization proceeded
normally with the formation of the 4-methyl isoborneol*
Graphically we may represent the reactions as:
They also pointed out the fact that the same compound
could be formulated from beta methyl camphene If It be assumed
that the only Isomerization taking plaoe In this case was the
normal Wagner ring Isomerization*The course of the reaction
thus would be:
Wagner Rearrang
4 Methyl Isoborneol*
Briefly, therefore, these Investigators proposed that
the complete explanation of terpene rearrangements Is dependent
upon two different types of isomerization;
one the Wagner
rearrangement which they designated as rearrangement of the
1st order and the other a simple plnacole-pinacoline change
which was designated as a second order rearrangement•
latter has since been called the Nametkin Rearrangement*
They further suggested that an explanation of the different
course of reaction shown by the alpha and beta methyl camphene
was to be found in the tendency of the OH to enter such a
position in the moleoule that ring isomerization will produce
a secondary alcohol*
However, it should be noted that this
condition would not be violated if it were to be assumed that
beta methyl camphene, after hydration, would undergo first a
Nametkin shift and then normal ring isomerization as indicated:
-1 6
The compound resulting would be 6-methyl camphor and since
the experimental compound obtained was shown to be Identical
with that previously proven to be 4-methyl camphor, this
series of reactions though possible does not apparently occur*
These Investigators have thus clarified the reactions encountered
In rearrangements amongst members of the terpene compounds *
It Is now necessary to turn briefly to a consideration
of studies of the hydration of pinene with mineral and organic
acids slnoe the condensation studied by the present lnvestli©
gator Involves the use of an acid medium* Slmonsen
has well
summarized most of the older literature based upon these studies?.
From his observations,It seems evident that the variety of
products and the complexity of the reaction appears to be
directly dependent upon the specific conditions and reagents
Among the many products Isolated by treatment of pinene
with conc. sulphuric acid are the monocyclic terpenes;
dipentene, terplnolene and terpinene*
Along with these there
have been obtained also camphene, in the dlcyclic series, and
some para oymene, the reference compound in the benzene series*
Mare recently Charlton and Day
report that the addition of
sulfuric acid in ethyl alcohol to para alpha d pinene produce
dipentene, p cymene, terplnolene*
Terpin hydrate was isolated
only from an aqueous wash after 3 or 4 days*
studying the methyl alcohol sulfuric acid treatment of Iso
cyclic hydrocarbons, observed that the alcohol added to a
-1 7
secondary tertiary double bond to form the corresponding
methyl ether*
Furthermore, if the double bond is dl-secondary
or dl-tertiary, no addition of the alcohol will take place*
From either alpha or beta pinene, he obtained alpha terplneol
methyl ether as the chief product when pinene was slowly dropped
into a boiling methyl alcohol sulfuric acid solution*
reaction was instantaneous and sufficient heat was developed
to carry the reaction along*
In this case the ether was formed
by opening the 4 membered ring and the methoxy group entered
into the tertiary position, since it could readily be split
from the compound by hot cone* formic or acetic and sulfuric
acid to produce the doubly unsaturated hydrocarbon terplnolene*
The preparation of terplneol through the hydration of
pinene first to terpin hydrate followed by subsequent dehydration of the latter has been reported by Acharya and Wheeler
These investigators found that by shaking 1 part of pinene
with 1*75 parts of 22-25/6 sulfuric acid in the presence of
gelatin as an emulsifier, they obtained a 40.3# yield of terpin
hydrate after 35-40 hours*
The preparation of borneoi by the hydration of pinene
has been the subject of several investigations*
reported that in an acetic acid medium pinene would produce
borayl acetate containing 25/6 of the lsobornyl ester and some
terpiny1 acetate*
acid and oxalic acid at low
found that phenol, salicylic
temperatures produced between
35 and 45$ borneol.
The best yield (60-70$) was obtained
with anhydrous oxalio acid and BS0S at between 0 and 20 •
reported that heating one mole of pinene with 70
grams of acetic anhydride plus 40 grams of BS0S at 90-95
for 40 hours, he obtained after saponification with alcoholic
K0H, 55$ of borneol and isoborneol along with the usual mono
and di-cyclic hydrocarbons and fenchyl alcohol*
Acetic acid
and the boron trioxide produced a slightly lower yield of the
same products*
He also obtained a good yield with anhydrous
oxalic acid and boroacetic acid*
Hirao and Takano
carried out a series of studies on
the hydration of pinene with phosphoric and sulfuric acids
in water and alcoholic solution of varying strengths*
phosphoric acid appeared to have no effect on the pinene, but
higher concentrations produced dipentene, camphene, terplneol,
ethyl terpinyl ether, p cymene and cineole*
At lower concen­
trations 40$ of camphene and other compounds were formed*
The results with alcoholic sulfuric acid were similar*
is quite evident therefore, that the product or products
formed by the hydration of pinene vary considerably in both
uniformity and complexity depending upon the medium and
conditions of the reactions*
$ince the present investigation is concerned with a study
of the condensation of pinene with formaldehyde in the presence
of acetic acid, it is important that at this point we review
the previously reported work on pinene and other terpene
formaldehyde condensations* As stated before, Kriewitz*
appears to be/first investigator to report the formation of
The report of his experimental work is rather
meagre, but it is known that he obtained reaction by heating
pinene, paraformaldehyde and ethyl alcohol in a sealed tube
for 12 hours at 170-175 * After twice distilling the reaction
product at normal pressure, he obtained 15# of a pure product
distilling at 232-236 and corresponding to the empirical
formula CxxHieO*
Though he did not propose a definite structure
for this product, he pointed out that it was an alcohol since
it could very readily be acetylated or benzoylated*
these derivatives were oils*
Both of
Upon treating the alcohol with
either concentrated hydrochloric or hydrobromic acids there
was formed a dihydrochloride and a dihydrobromide of empirical
formulas C xx HboO Br„ and CxxHso0 Cla*
It should be noted
that Kriewitz believed that since 2 moles of halogen acid
added to the molecule, the compound was lsomerized to the
dlpentene structure in the addition of the acid*
Because he
did not attempt in any other way to determine the degree of
unsaturation of the product of the condensation, his deduction,
in view of the ease of isomerization amongst the terpenes,
though plausible, is not necessarily valid*
The condensation
product may therefore have the dipentene structure even before
the addition of HC1 or HBr*
Furthermore, it is significant
that he reported the esters formed as a diacetate and a
This fact also hardly substantiates the assumption
that the condensation product was a mono hydroxy mono unsat­
urated alcohol with the original pinene skeleton, though it
could be inferred that the organic acid during esterificatlon
also isomerized the compound to another mono or di-cyclic
terpene alcohol*
Several years later, Genvresse
reported the same type
of reaction with the sesqul terpenes, caryophylene, clovene,
and cadinene.
At a slightly higher temperature the reaction
was again carried out in a sealed tube, but the time was
reduced to 10 hours*
The alcohols obtained analysed as mono
hydroxy alcohols of the general formula CieHaa0, indicating
the addition of one mole of formaldehyde to the hydrocarbon
The degree of unsaturation in the products was
determined by absorption of bromine*
Based upon these determin­
ations for the number of double bonds, the molecular refractivity of the compound was calculated*
This then was compared
with the observed molecular refraction and agreement was good
in all cases*
For the hydrocarbons caryophylene and clovene as
well as the corresponding alcohols obtained through condensa­
tion, only one double bond was observed*
From cadinene,
which has two double bonds, the alcohol obtained also showed
the presence of two double bonds*
It is to be deduced,
therefore, that addition of formaldehyde to these terpenes
was quite normal and did not Involve any isomerization*
-2 1 -
In 1919, Langlois
reported the condensation of camphene
with formaldehyde In the course of rather complete studies
of transformations In the camphene series*
He maintained
that an 11 carbon primary alcohol was synthesized as follows:
Cf^o -+• C H 3C o o H
The conditions for the formation of this compound
differed markedly from the previous authors*
This Investigator
heated trioxynethylene (25 grams) acetic acid (400 grams)
and camphene (200 grams) on an oil bath for two days so that
the temperature within the reaction flask was about 120 • At
the end of this time, since no solid trioxymethylene was left,
it was assumed that reaction was complete and the homogeneous
solution was then distilled*
Purification of this material
gave compound II in 17$ yield and determination of the sapon­
ification equivalent of the ester showed that 90$ of it was an
-2 2 -
ester of the formula CixHa,7COOCH8 a molecular weight of
Saponification of a large sample of the condensation
product yielded the alcohol III along with some ether CX1H 17
This alpha unsaturated primary alcohol was studied
quite completely and its structure determined rather conclu­
Esteriflcation produced the original ester which was
again titrated to determine its molecular weight*
checked with the original determinations*
Oxidation with
acid dichromate gave the corresponding alpha unsaturated
aldehyde, with its carbon content unchanged*
This aldehyde
was characterized by its semi-carbazone, indicating that the
original alcohol was primary*
Furthermore it was observed
that oxidation with permanganate in the presence of carbonate
produced the ketone camphenylone identified through its seml' carbazone,along with some camphenylic acid*
Stronger alkaline
permanganate oxidation produced camphenylone also,but at the
same time effected more vigorous oxidation producing other
isomeric degradation products*
From all these observations,
Langlois concluded that no isomerization took place in the
original condensation and that the reaction was simply
effected as previously formulated*
At about the same time, Prins
published several papers
on the condensation of formaldehyde with a wide variety of
unsaturated compounds, styrene, iso-safrol, anethole, pinene,
-2 3 “
d limonene, camphene, cedrene and some acyclic unsaturated
He proposed three different methods for the
1* Warming trioxymethylene and unsaturated hydro­
carbons in acetic acid solution
2* Warming the above components in a sulfuric acid
solution of acetic acid
3* Treating the unsaturated compound with 40$ HCHO
solution in aqueous sulphuric acid solution*
Reactions which were slow or negligible in the aqueous medium
were found to proceed more readily under the other conditions*
The nature of the products obtained was suggested by
Prlns according to a simple mechanism*
The reciprocal condens­
a t i o n between two unsaturated groups, one a simple double
bond, the other a carbonyl group, probably begins by the
addition of the groups to produce a 4 membered ring (I)*
now can absorb water to give a 1,3 glycol, or absorb another .
mole of formaldehyde to produce a methylene ether*
by either direct rearrangement or by indirect rearrangement
through the glycol, an unsaturated alcohol may result*
c —
CL —
C —
In an acid medium as for example acetic acid, the esters of
the corresponding alcohols and glycols will be formed*
Prins was able to obtain one or more of the products
he formulated by carrying out the reaction of the unsaturated
compound and formaldehyde under the variety of conditions
which he proposed.
He noted that isosafrol and anethole in
aqueous solutions yielded almost quantitatively the methylene
ethers, 3,4 methylene dioxyphenylbutylglycol methylene ether
and paramethyoxyphenylbutylglycol methylene ether respectively*
However, in an acetic acid solution containing sulfuric acid,
both the diacetate of the glycol and the methylene ether were
No general conclusion can be drawn as to the nature
of the products formed under these different conditions,for
camphene and cedrene yielded the acetate of the unsaturated
alcohol in the acetic sulfuric medium*
Furthermore, he reported
that at the boiling point of acetic acid alone, camphene,
d llmonene, and pinene yielded the corresponding acetates
of the unsaturated alcohols along with other higher boiling
compounds, whose chemical identity was not established*
In all cases saponification of the acetates gave the
corresponding alcohols*
Hydrolysis of the methylene ethers
however, was much more difficult*
With varying strengths of
oxalic and sulfuric acids, acetyl chloride and pyridine,
acetic anhydride and pyridine, acetic and sulfuric acids and
strong formic acid, the ether was unaffected or only reslnification resulted*
According to the mechanism of the reaction as proposed
by Prlns, it is evident that when the radicals attached to
the double bond are different two isomeric 4 membered rings
will form*
Recognizing this, Prlns studied the reaction of
styrene and was able to identify which Isomer formed*
reactions would be:
c M - C M 0/4-
-2 6 -
The ease of formation of the dlacetate from boiling acetic
anhydride, he maintained, was proof of the formation of the
glycol in series (1) since it is diprimary.
the other glycol is the hydrate of cinnamyl alcohol but all
attempts at dehydration and subsequent esterification to
form cinnamyl acetate failed*
Therefore he concluded that
addition must have taken place as formulated for series (1 )*
Prins obtained at least 70-90# of the theoretical yield
for almost all the condensations he reported with the notable
exception of those involving the terpenes*
In these cases
he obtained only small yields of pure substances, 15# being
converted into the unsaturated primary alcohol*
This low
yield he attributed to the formation of various side products
produced probably by further addition of formaldehyde to
unsaturated alcohol as follows:
It must be pointed out that the experimental data Prlns reported
does not of necessity indicate the complete course of the
reaction, nor does it suggest or prove any definite structure
for the products except as very simply formulated above*
-2 7
For the reaction with llmonene and formaldehyde, he wrote
the structure of the compound as:
In accordance with the suggested course of the reaction*
For the pinene product no structural formula was written*
The chemical Identity of the other compounds which were
higher boiling was not established*
Prlns also recorded a statement of Observations of
reaction between formaldehyde and amylene, citronellol,
oitronellal, methyl heptenone, undecylenic acid and ethyl
cinnamate without giving experimental data* Accordingly
Ritter and Frelrelch undertook the first extended study of
this general type of condensation with dllsobutylene, a simple
aliphatic oleflne*
Under the conditions used by Prlns, a
mixture of the acetate of the primary alcohol was obtained
along with other products*
Using acetic anhydride In place
of the glacial acetic acid, they obtained an Improved yield
of the primary alcohol as the only reaction product*
8 7
Is known to consist mainly of the
hydrocarbon R — CH*— C— CHa rather than its Isomer
R — CH=rC < (CH8 )a where R is the tertiary butyl group*
principal product obtained In the formaldehyde condensation
was R — CH*- C = CH— CHaOCOCH8 * Its identity was thoroughly
proven by oxidation of the alcohol obtained by saponification
of the ester, to the corresponding aldehyde*
This compound
was then dealdoled with aqueous sodium hydroxide*
and the tertiary butyl acetone were Identified as the products
of this reaction*
The present investigation was undertaken, as previously
stated, in an attempt to identify the products formed by the
condensation of alpha pinene and formaldehyde in an acetic
acid solution*
The presence of traces of mineral acid, as
for example sulphuric acid, was deliberately avoided so as
to eliminate the possibility of isomerization amongst the
compounds used and produced*
discussed at length*
This effect has already been
Furthermore the hydration of pinene to
borneol in the presence of acetic acid has also been reviewed*
This reaction has been shown to proceed usually in the presence
of some other catalytic agent —
Accordingly, it was
expected that the condensation of pinene with trloxymethylene
in the presence of acetic acid should proceed normally in
the formation of an unsaturated primary alcohol ester of the
pinene series*
Following the scheme presented by Prins, the
course of the reaction should be:
Ho Ac.
Series I and II both represent the normal course of
reaction as previously postulated*
It has been further
assumed that In the absence of mineral acids, none of the
rearrangements discussed at length were to be expected*
However from a consideration of the addition of halogen acid
to pinene which proceeds as:
it was recognized that the two electron pairs shared between
carbons No* 1 and 6 are held so that carbon No* 1 Is relatively
positive and carbon No. 6 relatively negative*
Only this con­
dition could satisfy the addition of halogen acid as shown*
Furthermore, a consideration of the electron arrangement in
a molecule of formaldehyde indicated that it would be
it a a
» SC*S*
in which case addition to the pinene molecule, if it be assumed
to go through the formation of a four membered ring could only
take place with the formation of Series I*
c U=o
-3 1 -
The expected compounds were therefore the ester of the
unsaturated primary alcohol and the corresponding ester of
the glycol of the pinene series*
The condensation was simply effected by refluxing the
three reactants at the boiling point of the acetic a d d *
The reflux period was varied between 14 and 72 hours*
table follows, showing the quantities of products obtained
from a series of condensations*
There was always obtained
a very large fraction boiling between 70 and 98 at 2 mms*
pressure and another fraction boiling between 120 -1 2 2 at
the same pressure*
In the chart the fractions obtained by
the vacuum distillation of the reaction mixture are designated
as I'low boiling alcohol ester**
(70-87°2 mma.)» 11 bigh
boiling alcohol ester'* (88-98°2
) and glycol ester*
6 ms* low 6 ms*hlgh
____________________________ fraction________
Reflux Holes of
6ms Pinene
2 *0
8 *0
Higher boiling than pinene at atmospheric pressure,
B. Pt. 170 - 180°.
—3 3 -
Saponlflcation of the alcohol ester fractions produced
the corresponding alcohol homoplneol previously reported by
It was noticed, however, that the head fraction of
the vacuum distillation of the alcohol after saponification
yielded a very low boiling solid when the temperature approached
This solid furthermore was soluble In the fraction that
followed and was at first thought to be the glycol.
this fraotlon was subjected to a steam distillation.
It was
expected that by this treatment separation could be effected,
the solid glycol remaining behind.
system distilled.
However, the whole fraction
Only after separating the distillate, drying
It and subjecting it to a redistillation, was the solid again
obtained on vacuum distillation.
Repeated distillations
yielded small amounts of a solid material which melted over a
4 degree range 148-152 • This solid has a distinct camphoraceous odor and does not react with potassium permanganate*
Accordingly it was assumed to be a saturated ketone, in aa
much as the presence of either a double bond or an hydroxyl
group would have produced reaction with permanganate.
it was observed also that this compound was Insoluble in both
cold and hot alkali, it could not be assumed to be an acid.
An elementary analysis confirmed the presence of oxygen In
the compound.
Therefore the possibility of it being an ether
had to be recognized, though at this point in the research,
the formation of the latter type compound was not considered
-3 4 -
Interpretation of the probable course of the rearrange*
ment in terms of well established reactions can be made by
a) allyl rearrangement of homopineol (I) to 6 methyl­
ene nopinol (II)*
b) Pinacol rearrangement of 6 methylene nopinol to
6 methylene isoborneol (III)*
c) hydration to 6 hydroxy 6 methyl Isoborneol (IV)
followed by 2 ,6 pinacol rearrangement of this
compound to the corresponding camphor (V)*
C4 =q
-3 5 -
Pinaool rearrangements of the type shown above are quite
common among the bicyclic terpene derivatives and have been
discussed at length previously*
Identification of the solid obtained from the head
fractions of the alcohol distillation as 6 methyl camphor,
necessitated the preparation of this solid in larger quantities*
Towards this end isomerization of homopineol was attempted
under a variety of conditions;
refluxing with dilute alcoholic
alkali, refluxing with dilute sulfuric acid, treatment at
0° with 65$, 75$, 85$, and 95$ sulfuric and concentrated
sulfuric acid in ether.
In the first case, no solid was
obtained, and refluxing with sulfuric acid produced a new
liquid compound, boiling between 60-65° at 3 nuns, which
probably was an hydrocarbon*
The remaining series of reactions
only produced very small quantities of the camphoraceous solid,
0*3-0*7 grams from 17 grams of homopineol*
It could hardly be
assumed that this material was produced by the isomerization
of the alcohol, but rather that it was present originally in
the alcohol as an impairlty*
It now appeared likely that this camphoraceous product
was one of the products of the original condensation*
glance at the chart of the fractions obtained from the con­
densation would seem to confirm this assumption*
The like­
lihood of one single pure product boiling over a 30 degree
range is quite improbable*
Furthermore considerable quantities
of this compound would be expected to appreciably affect the
boiling point of the ester*
The separation of the alcohol
-3 6 -
eater products into two different fractions, though premature
and rather arbitrary aided materially in the final Isolation
of this product*
Subjecting the ” low alcohol ester fraction”
to repeated vacuum distillations, soon revealed that the
solid was present in this fraction*
However it was readily
soluble in the alcohol ester fraction which followed it and
separation from this ester appeared almost impossible*
The use of a simple vacuum distillation set-up was
therefore abandoned and fractionation was attempted in vacuo
using a long, heated fractionating column*
It was possible
in this way to bleed out the solid from the ” low boiling
alcohol ester” fraction*
At between 52-55
the solid would appear along the column*
and 4 mms* pressure
When no more solid
could be obtained from a given amount of ester, the distillation
was stopped*
This material was then readily removed from the
column, by running a quantity of either acetone or ether
through the system*
Evaporation of the solvent at room
temperature left considerably increased amounts of the solid*
It was soon noticed that this material readily sublimed at
room temperature and could not be allowed to dry overnight
on a clay tile without considerable loss*
Even when 10 grams
of the material were dried in a desiccator over sulphurio
acid, as much as one gram loss In weight was observed for &
24-hour period*
The material was further found to be quite
soluble in almost all common solvents;
alcohol, ether, acetone,
acetic acid, methyl alcohol, pinene, di-isobutylene and a
variety of other substances*
In water only the slightest
-3 7
solubility was observed as evidenced by the effect on the
surface tension of the former, a characteristic property
peculiar to camphor*
be steam distilled*
From water this material can readily
In concentrated nitric acid there is
observed the formation of a green oil in the same manner as
with camphor*
The marked similarity between the properties of this
compound and those of camphor seemed to justify the formu­
lation of the structure of the compound as that of 6 -methyl
camphor as previously postulated*
It need only be assumed
now that the rearrangements suggested before take place during
the condensation*
There can hardly be any objection to such
an assumption in view of the ease of Isomerization in the
pinene series already reviewed at length*
The mode of isolation of the material by fractional
distillation in vacuo though an improvement, could hardly be
considered adequate*
Large quantities were required before
purification of the material could be attempted as the melting
point often varied between 105 and 140°*
Because of its high
solubility in organic solvents, recrystallization was impossible*
It was therefore decided that perhaps isolation could readily
be effected through the formation of a simple ketonic derivative,
the oxime.
This would afford at one and the same time isolation
of the material, confirmation of the presence of a carbonyl
group and a means of purification*
Accordingly 50 gram samples
-3 8
of w low alcohol ester** fraction were treated with hydroxylamlne hydrochloride, and alkali .in an alcohol solution*
solid oxime was obtained*
Vacuum distillation of the product
showed the presence again of the camphoraceous solid and a
higher fraction probably alcohol*
This is the first indication
that the previously proposed structure for the solid might not
be correct*
It has been known for a long time that camphor can form
a constant boiling compound with phenol®8•
Therefore it
appeared possible to achieve the isolation of a quantity of
the solid through an analogous reaction*
Accordingly this
was attempted with the column previously used in the vacuum
After collecting the head runnings by distilling
a large amount of ** low alcohol ester** fractions one mole of
phenol was added to the ester and the distillation was continued*
At between 3-4 mms. a considerable amount of a constant boiling
compound (64-65°) was isolated*
When the temperature began
to rise, the distillation was again stopped and an additional
86 grams of phenol added*
This time 40 grams of pure phenol
were obtained and then an additional quantity of the constant
boiling compound*
It was now assumed that since pure phenol
was first obtained, all the solid material had now been
removed by combination*
From approximately 700 grams of
*(Low alcohol ester** fraction, there was obtained 280 grams
-3 9
of the constant boiling compound.
When the latter was
redistilled, 240 grams of pure addition compound were
Treatment with the calculated amount of a 20%
KOH solution yielded 93 grams of solid and 64 grams of an
oil which smelled strongly camphoraceous*
This method of
isolation of the compound was therefore very successful*
It now remained to be proven that the compound obtained
was a camphor*
The complete failure to obtain any of the
characteristic functional derivatives— oxime or semicarbazone
seemed to indicate that the compound was not a ketone*
firmation of this fact was then sought by a comparison of the
absorption spectra of the solid with that of camphor*
It was
expected that
any trace of carbonyl would probably
mined in this
The complete absence of any
absorption, contrasted markedly with the characteristic
absorption exhibited by camphor and
the idea of a
led the author
ketonic structure for the compound*
As previously mentioned, the presence of oxygen in the
compound was determined by an elementary quantitative analysis*
The absence of an hydroxyl, carboxyl or carbonyl groups as
demonstrated by many observations and reactionscould only mean
that the oxygen was present in an ether type of linkage*
Further the mode of isolation of the compound is not incom­
patible with these facts.
The saturated monooyolic ether
cineole (29) which possesses a characteristic camphoraceous
odor is usually characterized by the preparation of a solid
-4 0
compound with ortho cresol or resorcinol*
The structure
therefore of the compound now believed to be an oxide might
be either I or II:
depending upon whether or not rearrangement did or did not
No formulation of a mono cyclic ether is possible
since it would contain either a double bond or another
hydroxyl group*
Since the compound does not react with cold
permanganate nor sodium, such a formulation is not possible*
Furthermore, it must be repeated that addition reactions
involving halogen acids or mineral acids usually result in
the formation of either monocyclic compounds or derivatives
of the camphane or fenchane series*
In all cases the cyclo
butane ring is not carried through the reaction as such*
is either broken completely or merely enlarged by rearrange­
True pinene derivatives, i.e., those which possess a
cyclo butane ring are not common under normal reaction
In the formation of bornyl chloride in preference
to pinene hydrochloride, Aschan
contended that the pinacollne
-4 1 -
change proceeds faster than the addition of the halogen acid
to the hydrocarbon.
Accordingly structure I has been adopted
as the probable structure of the ether*
The most significant reaction which this new ether was •
found to undergo was that of oxidation by fuming nitric acid
under the same conditions by which borneol may be oxidized to
Steam distillation from an alkaline solution resulted
in the isolation of both unreacted ether and another product*
The latter was obtained by precipitation from the alkaline
solution upon the addition of dilute sulfuric acid*
It was
first thought to be an acid but a micro titration for carboxyl
proved of no value*
The end point was not too distinct and
faded gradually until the theoretical quantities of acid and
alkali were neutralized*
This observation is usually made
in the titration of lactones and it was therefore assumed
that the compound was a lactone*
Its solubility in only
- hot alkali seems to be in harmony with the former observation*
The reaction is therefore formulated as:
/©*- /£■*
-4 2 -
Houben81 has described a very similar compound, 6 -hydroxy
camphane 2 -carboxylic acid prepared through a series of reactions9
starting with bornyl magnesium chloride and carbon dioxide*
The possibility of a difference in the stereo chemical nature
of this compound and the compound isolated above must not
be neglected*
However it was thought that it should be possible
to hydrolyse the above lactone to the corresponding hydroxy
camphane carboxylic acid*
This was attempted with both dry
HBr in acetic acid solution and boiling HI*
In the former
case only Impure lactone was recovered* In the latter case a
compound which reddens at 173 and melts sharply at 195 was
This compound further showed no positive iodine
test either by use of copper wire or from a sodium fusion
test solution*
Analysis of this compound gave practically the
same results as the original lactone*
Since the melting point
of this compound was not within the range of either camphane
carboxylic acid reported in the literature, it had to bo assumed
that no reaction was produced by the boiling hydriodic acid*
The product obtained was in all probability impure lactone*
Houben81 reported also, the oxidation of 6 hydroxy
camphane 2 carboxylic acid to the corresponding 6 keto acid,
whose melting point did not differ markedly from the original
hydroxy acid*
His procedure was attempted on the lactone,
-4 3 ketonic acid was Isolated*
No semicarbazone could be
obtained from the product of this reaction and It had to be
assumed that the original compound was unaffected by this
It was observed In the course of one of these
experiments that even after 3 hours of boiling In sodium
carbonate solution, some of the lactone still appeared Insoluble*
It must be stated that all of these reactions were carried
out only on small quantities, which fact may or may not account
for the difficulties in isolating the expected products*
the other hand, the lactone in question is undoubtedly a
stereo isomer of the known hydroxy camphane carboxylic acid
and may therefore react quite differently from it.
further attempts were made to elucidate its structure*
It was now decided to reinvestigate the structure of
Prlns reported the presence of only one double
bond in this compound, and therefore it was to be assumed
that the pinene nucleus remained
intact in the course of
However reduction of 1 mole of homopineol with
hydrogen in the presence of Rainey nickle, showed that not
2 grams of hydrogen were absorbed, but rather 4 grams*
could only mean that homopineol had two double bonds, instead
of one, and was in all probability a oompound of the dipentene
Ring rupture during the course of reduction
appeared unlikely in view of the fact that the pinenes can be
reduced catalytlcally to pinane without ring fission**.
-4 4 -
Since it has long been known that the doubly unsaturated
monocyclic compounds may readily be isomerized to the parent
aromatic hydrocarbon, para cymene, it was thought that
homopineol should produce the corresponding methyl cymene—
1,2 dimethyl 4 isopropyl benzene*
Carved ®3 when heated with
sulphuric acid produces para cymene*
When alpha terpinene84
is heated with sulphur, the same aromatic hydrocarbon is
obtained in 50# yield*
this type of change*
Iodine has also been used to effect
Baeyer and Villiger88 observed the
catalytic effect of iodine on the conversion of monocyclic
terpene derivatives into the corresponding benzene hydro­
They accomplished the change by completely brominating
the compounds and then effecting the removal of halogen acid
by treatment with zinc dust and hydrochloric acid followed by
sodium in ethyl alcohol, potassium permanganate and ultimately
a distillation from sodium*
In this manner from llmonene
they obtained para cymene and from carvestrene the meta cymene*
Sulphuric acid treatment of the alcohol had been attempted
previously when it was first thought that the latter could
be isomerized to the ether obtained in the condensation*
Repetition of this experiment yielded a liquid boiling between
60°-64° at 3 mms* which reacted readily with bromine in carbon
tetrachloride and with potassium permanganate*
not the expected aromatic hydrocarbon*
This then was
Examination of the
literature reveals that this compound might well he a
methylene para menthatriene®6 resulting from the dehydra­
tion of the alcohol as follows:
-4 6 -
It was then thought that the dehydrogenation and Isomer­
ization might well be accomplished by the use of Iodine*
Keeping In mind the fact that Baeyer and Villiger suggested
that this reagent was catalytic In effect on the monocyclic
bromides at least, It was added to the alcohol In small
It Is significant that heat of reaction can be
detected almost Immediately and If not properly controlled,
the reaction will promptly proceed vigorously with the form­
ation of resinous materials*
By the use of a suitable solvent
the reaction can be made to proceed quietly*
The product
obtained by this treatment was then subjected to a rather
rigorous purification involving (1 ) shaking with cold perman­
ganate several times, (2 ) refluxing over sodium followed by
distillation from the sodium, (3) shaking with cold concen­
trated sulphuric acid, (4) washing with dilute alkali and
water and finally (5) a vacuum distillation*
» now free from all olefinic compounds*
This product Is
Its physical constants
agreed with those of the expected methyl para cymene87*
Aromatic hydrocarbons are usually characterized by either
nitration or oxidation products*
The nitration of para cymene88
is carried out under rather unusual conditions, l.e* at low
Apparently at room temperature nitric acid
reacts.violently producing a variety of oxidation products
along with the nitro compounds.
Although no nitro compounds
were recorded for the methyl cymene, an attempt was made to
-4 7 -
nitrate this compound*
Since it was observed to react
violently with the nitric sulphuric acid mixture at room
temperature, the reaction was carried out in the same manner
as for para cymene*
Only an oil was obtained and therefore
this method of identification was abandoned*
• Oxidation studies were then made*
It was at first thought
that oxidation with, potassium permanganate could be effected to
the corresponding tribasic acid, trimellitic acid*
This was
attempted according to the conditions used to oxidize pseudo
No trimellitic acid was isolated, but rather an acid
oxidation product analysizing for 72.0$ carbon and 8*7$
hydrogen which could only indicate partial oxidation*
calculated quantities of hydrocarbon and oxidizing agent were
used, there was a considerable excess of permanganate at the
end of the reaction*
The odor of the hydrocarbon was still
noticeable and the amount of product was very small*
The use
of potassium permanganate was therefore abandoned in favor
of dilute nitric acid which is more effective in oxidizing a
aide chain other than methyl*
The oxidation of pseudo cumene with dilute nitric acid
was carried out by Perkin and co-workers®9*
Among the
products obtained are the ortho xyllc and para xylic acids as
well as the dibasic acids methyl terephthalic and methyl
Under the same conditions 1, 2 dimethyl 4
isopropyl benzene should yield para xylic acid and both of
the dibasic acids mentioned before*
Upon carrying out the
-4 8 -
reaction, It was observed that oxidation proceeded efficiently,
and a good yield of the mixed acids was isolated*
of the monobasic acid, para xylic acid, was effected from the
dibasic acids by dissolving the mixture in chloroform and
filtering off the insoluble dibasic acids*
Evaporation of
the chloroform left the monobasic acid*
During the early part of this study, there were several
isolated observations and reactions carried out which will be
reported at this time*
First among these reactions were
several oxidation studies made in an attempt to Isolate
pinonic acid*
This would have been the normal oxidation
product of homopineol if it were a true pinene derivative*
The oxidation was carried out in the same manner in which
pinene is most readily oxidized to pinonic acid, i.e., in a
buffered permanganate solution*
Although pinene yielded
pinonic acid, none of the latter was ever obtained from
In this case, the product was always an oil which
showed an acidic reaction to litmus and a positive iodoform
Since it was later demonstrated that homopineol was
a dipentene derivative, it may now be understood why pinonic
acid was never obtained*
If any oxidation did take place,
one of the probable compounds would be the diketonlc acid
described in the literature by Harries and Adams40 as an
Its structural formula is:
C H a - C - C H a — CHa— CH— CHaCOOH
0 * C CHa
-4 9
This compound would certainly show a positive iodofornutest*
Furthermore, any of the other degradatlve compounds obtained
from llmonene would be just as likely to be present*
positive Identification of the syrups was ever made*
Homopineol was treated with phosphorous trichloride to
produce the corresponding chloride*
Dry hydrogen chloride
was then passed Into this compound at 0° in an attempt to
get a solid halogen derivative*
Absorption of the hydrogen
chloride was evidenced by an increase in weight, but no solid
was obtained*
Treatment of the saturated chloride solution
with alcoholic potassium hydroxide only produced a new liquid
compound boiling at 55°-60° at 2 mms*
This compound was quite
unsaturated but did not yield any solid bromide derivative
when treated with bromine in either carbon tetrachloride or
acetic acid*
No real work was attempted in examining the structure of
the glycol or the glycol ester*
Only when it was thought
that isomerization of the alcohol should produce the ketonic
compound, later identified as an ether, did it seem logical
that the glycol or its ester should also lsomerlze to this
Towards this end, the hydration of the alcohol
in a bomb was attempted*
It was hoped in this way to form
the glycol and then to cause its subsequent rearrangement*
Most of the alcohol was recovered unchanged*
The glycol ester was also treated with approximately 25%
sulphuric acid at 0° in an attempt to cause isomerization*
Here too the glycol ester was recovered unchanged*
Condensation of alpha Pinene with Trloxvmethylene In Acetic Acid
4 moles (544 grams) of a^pha pinene (** Hercules III »* )
purified by distilling from sodium, 120 grams of trioxymethylene,
and 453 grams of acetic acid are mixed together and refluxed
gently for 56 hours*
There is some tendency to depolymer­
ization of the para formaldehyde resulting in evolution of
formaldehyde if the boiling is violent at the start*
gas so evolved repolymerizes on the cold condenser wall with
gentle boiling however, and eventually returns practically
completely to the reaction mixture*
During the first two
hours therefore, the condensation must be watched carefully
to make sure that at no time the condenser becomes clogged*
After this period the mixture is allowed to boll more actively*
At the end of the reflux period a clear solution, ranging in
color from straw yellow to a light brown, is obtained*
solid remains*
This solution is then distilled at atmospheric
Acetic acid, water and unchanged pinene distill
at first, leaving behind a mixture consisting principally of
homopineol acetate, a glycol ester, 2,6 camphane methylene
ether and polymerized material*
Distillation of this mixture
in vacuuo at 3 mms* pressure yielded 221 grams of **Low boiling
ester fraction** 70-90°, 111 grams *» high boiling ester
fraction** 90-98°, and 120 grams of glycol ester boiling
-5 1 -
As previously stated, this condensation was effected at
- varying reflux periods, The chart on page 32 indicates
variations in the yield of materials obtained for all
condensations carried out*
The ether is present in the * low boiling ester fraction**
and was isolated from this fraction*
Homopineol Acetate
Bolling point - 88*5-89*5° at 1 mm*
d**°° »
Saponification Equivalent
74*92 C
9*60 H
74*74 C
9.96 H
-5 2 -
Saponlflcatlon of homopineol acetate
416 grams of ester (2 moles) are boiled with 122 grams
of KOH in 650 cc. of ethyl alcohol for 20 hours*
The ethyl
alcohol is removed by distillation and the crude product is
washed, dried (KgCOs ) and distilled in vacuuo*
Yield = 270 grams (81# of theory)
In some cases separation of the crude product by a water
wash produced emulsificatlon and it was necessary therefore to
at least partially acidify this mixture and proceed to isolate
the alcohol by an ether extraction*
The yield by this procedure
is somewhat higher— 95# of the theoretical yield*
A small sample purified through the borate showed:
Boiling point
at 2 mms*
Reesteriflcatlon of Alcohol
15 cc. of homopineol and 15 cc. of acetic anhydride
were heated together on a water bath for 5 hours.
25 cc. of
water were added and the mixture boiled for 10 minutes to
hydrolyse any unreacted acetic anhydride.
The ester was then
separated, washed with dilute sodium carbonate and then with
water, dried and vacuum distilled*
Yield - 10 grams of ester
Bolling point - 88-89 at 1 mm*
1*4769 (freshly distilled)
18n *0wS
Calculated * 74*94
* 75.10
Saponification Equivalent
Calculated = 208
* 215
Attempted Isomerization of Homopineol
15-16 cc. of the alcohol were added slowly with
stirring to a beaker containing sulfuric acid and cooled in
a salt-ice mixture*
The strength of the acid was varied in
several experiments, 65$, 75$, 85$ and 95$.
95$ sulfuric in ether was used.
between two and three hours.
In one instance,
The time for addition was
At the end of this time the
reaction mixture was added slowly to cracked ice and allowed
to stand.
Steam distillation of the resulting solution
produced only small quantities of solid melting between
A small amount (0.3-0.7 grams) of oil is also
The material was later identified as an impurity
present in the original alcohol.
claimed by this treatment.
No Isomerization could be
Isolation of 2.6 oamphane methylene ether
776 grams of ** low boiling ester** fraction were
distilled in vacuuo through a 20 plate barostated fractionating
There was obtained a head fraction (70 grams) which
consisted probably of hydrocarbon* At 55 and 4 nuns* pressure
solid began to appear at the base of the column*
distillation was stopped and one mole of phenol (94 grams) was
then Introduced into the distillation flask*
The distillation
was then continued and the fraction between 64 and 68 (3-4 mms)
was collected*
When the distillation temperature began to
rise the distillation was again stopped and a second portion
of phenol (86 grams) was added*
The distillation was continued
and for several hours pure phenol distilled out, boiling at
55° at 3 1/2 mms*
Forty grams of phenol were obtained and
then more camphor phenol was obtained*
camphor phenol was 280 grams*
The total yield of
This material was then subjected
to redistillation through the column and 231 grams of camphor
phenol were obtained*
Boiling point— 64*5-66*0° at 3 1/2 mms*
The camphor phenol was then treated with 75 grams of KOH
in a 20% solution and shaken thoroughly in a separatory
The alkali was drawn off and the solid which appeared
quite oily was again washed with 25 grams of KOH in 100 co*
of Ha0 and finally with cold water* - As a result of this
treatment, approximately 100 grams of the solid ether and
55 grams of an oil which still smells strongly camphoraceous
were obtained* Melting point of the product as obtained
123-126 (with sublimation)*
56Purlficatlon of 2.6 camphane methylene ether
Approximately 10 grams of material obtained from phenol
treatment were dissolved In 9 cc. of methyl alcohol and added
to 50 cc. of concentrated HC1 In a separatory funnel*
solution becomes dark red In color.
low boiling petroleum ether*
It Is then shaken with
The acid solution Is drawn
off and run Into 200 cc. of cold water and the solid again
It Is filtered off and all the operations
are repeated*
This time the solid is washed further with
dilute NaBC03 and water before drying*
of this material is 147-150°•
This solid is now distilled
from a solution of 1 gram of KMn04, 5
cc* of water*
The melting point
pellets of KOH and250
The permanganate color remains
after the
distillation is completed and there is obtained two grams
of pure white material*
After drying the melting point
obtained is 147-149°, the freezing point 148°*
Calculated 79*52
Upper Part
Absorption Spectra of 2,6 camphane methylene ether
Lower Part
Absorption Spectra of camphor*
-t57Oxidatlon of 2.6 camphane methylene ether
A solution of 21.1 cc. of concentrated nitric acid
(sp. g. 1*42) and 3*7 cc. of fuming nitric acid (sp. g. 1.59)
is cooled with stirring In an Ice, salt mixture* The temperature
of this mixture is brought to 5 and then 15 grams of the
solid ether are added slowly so that the temperature during
the addition is maintained between 8 and 12 • The total
time for the addition of all the solid Is between 2 and 2 1/2
The reaction mixture is then further stirred for 1
At the end of this time, it Is added slowly with
stirring to the beaker containing approximately 125 grams of
crushed ice*
When all the ice has melted, the water is removed
by decantatlon and the solid washed with fresh water*
It is
then filtered and added to a 500 cc. round bottom flask
containing 7 grams of potassium hydroxide dissolved in 300 cc*
of water. Steam distillation/o*5 grams of apparently unreacted
impure ether melting over a range between 120 and 130 •
Acidification of the alkaline solution with dilute sulphuric
acid yielded 6*0 grams (37/0 of crude lactone*
After being
twice recrystallized from dilute ethyl alcohol, the melting
point of this lactone is 214° - 215° using a Fischer
Mol. Wgt.
Calc. C 73*29
H 8*94
HBr Treatment of Lactone
Dry HBr is generated by dropping bromine on naphthalene*
The gas is passed through HaS04 before being led into the
reaction chamber*
1*5 grams of lactone were dissolved in
6 cc* of acetic acid and placed in the reaction chamber which
was then cooled to between 5 and 7 • After the gas was
passed into the acetic acid solution of the lactone for one
hour, solid appeared, but this soon disappeared as the flow
of gas was continued*
After 3 1/2 hours, the addition of
HBr was discontinued, and the flask stoppered and set aside
to stand overnight*
No precipitate was obtained*
solution was then transferred to a crystalline dish and
allowed to stand over the week end*
appeared to be unchanged*
Melting Point 208°-9°
The solid remaining
-6 9 -
HI Treatment of Lactone
0*65 grams of lactone were boiled with 15 cc* of
HI (sp* g* 1*7) in 5 cc* of*acetic acid for 4 hours.
reaction mixture was worked up by adding alkali until the
solution was strongly alkaline*
This solution was then
ether extracted to remove any impurities*
then produced a dark red solution which was again extracted
with ether*
The latter extracts were washed with water,
thiosulphate and water again*
Evaporation of the ether
yielded 0*5 grams of solid material which was recrystallized
once from dilute alcohol*
Iodine test by sodium fusion
method was negative*
Mpt* 195° u*c* (with darkening)
—$ 0 —
KMn04 Oxidation of Lactone
1 gram of lactone, 2*5 grams of sodium carbonate and
60 cc. of water were mixed together in a 250 cc* three-necked
flask and set under reflux over a small free flame*
14 cc*
of a 0> KMn04 solution were added slowly and after the
addition was complete, the reaction mixture was heated
further for 2-3 hours*
The permanganate color remains even
after the reflux period is completed*
The unreacted per­
manganate was destroyed by the addition of small quantities
of ethyl alcohol*
The manganese dioxide was filtered off
and the alkaline solution acidified*
Extraction with ether
yielded 0*5 grams of material which was recrystallized from
dilute ethyl alcohol* Mpt* 198 - 202 u*c*
2.6 keto camphane carboxylic acid CxxHxs0B
2.6 camphane carboxylic lactone
C 68*87
H 8*16
CxxHxe°s C 73*29
Oxidation was not effected to the keto acid*
-6 1 -
Reduction of Homopineolt
214 grams of alcohol (1*3 moles) were reduced catalytically In a bomb with Rainey nickel*
Rainey nickel In ethyl
alcohol (5-10$ of the weight of the alcohol) was the catalyst
The temperature of the bomb was kept at 100°•
2-3 hours an approximate decrease of 400 lbs. of pressure was
Then there was a further gradual absorption of
hydrogen corresponding to a decrease of another 400 lbs* until
the reaction was complete*
The total decrease In pressure
corresponds to the addition of 4 grams of hydrogen indicating
therefore the presence of 2 double bonds in the molecule*
The bomb was allowed to cool slowly*
The product was worked
up by decanting from Rainey nickel and subjected to vacuum
distillation after ethyl alcohol was removed*
Boiling point = 107-111° at 8 mms* redistilled at 2 rams*
boiling point 84-86°*
a 0*9421
» 1.4812
C X1HS80
Calculated = 77*65 C
12*94 H
* 77*96 C
12*80 H
Filtration to remove Rainey nickel even through fritted
glass was not too efficient*
Yield » 200 grams*
Oxidation of tetrahydro Homopineol
15 cc* of concentrated HaS04 were added to 200 cc* of
water and 25 grams of sodium dlchrornate dissolved In this
This mixture was transferred to a glass stoppered
bottle and 25 grams of ttoe above, cxgd were added*
The mixture
was shaken for 1 1/2 hours and then allowed to stand overnight*
At the end of this time, there were two defined layers in the
reaction bottle*
Salt was added and the mixture ether extracted
washed and dried*
After the ether was removed, the solution
remaining was vacuum distilled.
Eight grams of oil were
B.Pt*: 57-59° at 2 mms*
This compound gives a
positive Schiff's test*
0*5 grams seml-carbazide HC1 and 0*7 grams
of sodium acetate are weighed out and dissolved in 5 cc* of
water in a 50 cc* Erlenmeyer flask*
0*5 cc* of aldehyde are
added and then sufficient ethyl alcohol to make the mixture
This solution was stoppered, shaken from time to
time and then allowed to stand*
separated out*
After five days crystals
The semicarb&zcss was recrystallized from
dilute ethyl alcohol (1*2)*
C laHa5N80
Calculated *= 18*66
Melting Point 233-4°
» 18*87
Catalytic Dehydrogenation and Isomerization of Homopineol
60 cc* of the alcohol were dissolved in 30 cc* of
chloroform in a 500 cc. three-necked flask and placed under
Three grams of iodine were added in small portions
over a period of twenty/five minutes*
The first portions
dissolve rapidly and are soon absorbed*
Shaking hastens this
After the addition of approximately 2 grams, the
iodine color persists and further additions of iodine produce
Upon completing the addition of the iodine, the reaction
mixture was refluxed for 4 hours*
At the end of this time,
it was cooled and an additional 2 grams of iodine were added*
Refluxing was continued for three hours•
The reaction mixture
was then allowed to stand overnight*
The resulting chloroform solution was found to contain
droplets of water as is to be expected from the course of the
This water was first removed and then the chloro­
form was distilled off*
After the last traces of chloroform
were removed, a spontaneous reaction continued in the distilling
flask and more water was obtained*
obtained was 3*5 cc*
Total volume of water
The product was now washed several times
with sodium thlosulphate, dried and vacuum distilled*
22 grams
of a liquid boiling between 40° and 55° at 2 mms* were
Purification of this product was carried out by washing
twice with cold dilute potassium permanganate*
After the
-6 4 -
second washing, the permanganate color persisted*
material was then dried carefully and distilled from sodium*
The fraction boiling between 193° and 210° at atmospheric
pressure was collected*
This product was now washed two times
with cold concentrated sulphuric acid and finally with water,
sodium carbonate solution and water*
It was then dried over
anhydrous calcium chloride and vacuum distilled*
8 grams of
this product were obtained*
83° - 86°
15 mms.
85° - 88®
17-18 mms*
Found 87*56
-6 5 -
KMnQ4 Oxidation of 1,2 dimethyl lsopropyl benzene
Equation for the oxidation:
10 KMnO* + C XXHX 6
* 10 MnOB + C9H806Ka + 2 C09 + 7 KOH + 3 Hs0
1*5 grams ofhydrocarbon obtained from the previous
treatment were refluxed with 16 grams of potassium permanganate
and 4 grams of magnesium sulphate in 300 cc* of water for
5 hours*
At the end of this time the permanganate color
persists and the odor of the hydrocarbon is still detectable*
Accordingly the buffered solution was made strongly alkaline
by the addition of five grams of potassium hydroxide*
was continued for an additional 5 hours*
The reaction was
then worked up*
The excess permanganate was destroyed by adding-sodium
bisulphite and the manganese dioxide was filtered off*
clear alkaline solution was then extracted with two 15 cc*
portions of ether
and then evaporated until the solutionwas
known saturated
with the salts present.
It was then
acidified with sulphuric acid and extracted with three 50 cc*
portions of ether*
Evaporation of the ether left a small
amount of solid which was only once recrystallized from water*
Mpt* of crude material
130° - 150°
Mpt* of recryst* material180° —
210° with darkening
Found C 72*02 Calc* for trimellitic acid
C 9H806
Oxidation is incomplete and does not proceed acoording to the
equation given above*
-6 6 -
Dilute Nitric Acid Oxidation of 1.2 dimethyl/lsopropyl benzene
2*5 cc. of hydrocarbon were mixed with 65 cc. of dilute
nitric acid (1:3) and refluxed for 8 hours*
The solution was
allowed to cool and a large crystalline precipitate was
This material was filtered, washed several times
with water and then purification was attempted*
The product
was dissolved in sodium carbonate solution and extracted three
times with ether*
The water solution was allowed to stand
to insure evaporation of all the ether dissolved In it*
acids were then reprecipitated from this carbonate solution
by the dropwlse addition of hydrochloric acid*
The solid
precipitate was filtered, washed several times with water
and then dried*
A melting point of this material revealed that a mixture
of acids had been obtained by this method of oxidation*
mixture first melted at 140° and was not completely melted
until the temperature had been raised to 289°.
the mother liquor of the first filtration yielded a small
amount of material which appeared wet at 151 but melted
completely between 280° and 289°*
No purification or separa­
tion could be effected by recrystallization from either water
or dilute alcohol*
By a comparison with the results obtained in oxidizing
pseudo cumene according to this procedure, it was expected
that the principal products of the oxidation of 1,2 dimethyl H
lsopropyl benzene would be para xylic acid, methyl terephthalic
-6 7 -
acid and methyl Isophthalic acid*
The melting points given
for these acids are 163°, 325° - 330°
285° - 290°*
and 320° - 330°
Mixtures of the two dibasic acids melt at
The dibasic acids are practically insoluble in
most organic solvents, whereas the monobasic acid is soluble*
Separation of the mixture obtained in the oxidation was
therefore attempted by taking advantage of the difference in
A portion of the solid mixture of acids was shaken
with chloroform and filtered from the insoluble material*
Evaporation of the solvent left the mono basic acid*
the quantity of material obtained in this way was rather
small, no further purification was attempted*
Mpt. 153° - 157°
Calc, for para xylic acid
Calc, for methyl phthallc
Found (low melting solid)
Found (High melting solid)
PCIa treatment of the alcohol
70 grams of alcohol were dissolved in 50 cc# of petroleum
ether In a 500 cc# 3-necked flask, fitted with a dropping
funnel, stirrer with a mercury seal and reflux condenser#
flask was cooled to 0° In a salt, water and Ice mixture#
15 cc. of PC18 were added slowly over a period of 1 1/2 hours#
The reactants were further stirred at 0° for two hours and
then allowed to warm up to room temperature#
then was allowed to stand overnight.
This mixture
No two layers, nor any
evidence of syrupy phosphorous acid and red phosphorus were
More petroleum ether was added and this solution
was washed repeatedly with dilute NaaC0s and Ha0#
petroleum ether solution was finally dried over anhydrous
Removal of the petroleum ether followed by vacuum
distillation yielded 45 grams of product and 23 grams of a
gummy residue# Boiling point - 70-71 at 5 mms# and
92-94° at 15 mms#
The compound was not further characterized
since it was hoped it could be converted to a solid chloride
by addition of dry HC1#
This chloride was then redistilled (35 grams) and divided
into two separate portions for addition of HC1#
It was treated
in the same manner as plnene is in its conversion to bornyl
chloride# The addition was carried out first at 0° and then
at 15 when darkening occurred. The temperature of the reaction
mixture was then reduced again to 5°#
Accordingly on the second
-6 9 *
run, the temperature was kept between 0
and 5
but this
did not prevent the darkening of the reaction mixture*
No. 1 was worked up washing with water, dilute alkali and
water again.
an oil;
Vacuum distillation only yielded 14 grams of
boiling point 90-110 at 8-9 mms* No solid
chloride could be obtained*
Run No. 2 likewise could not be made to yield a crystalline
chlorid^kven when cooled in dry ice and acetone.
up in a slightly different manner*
It was worked
There was observed an
increase in weight of two grams after the addition of dry HC1
to 14*5 grams of the chloride dried for several days over
anhydrous Na8S04 before treatment with HC1*
This product was
dissolved in 60 cc. of alcohol and 10 grams of KOH in 100 cc*
of alcohol were added to the solution*
This mixture was
refluxed 4 hours and worked up in the same manner as was the
alcohol from the saponification of the ester.
Only 5 grams
of an oil with a boiling point of 55-60° at 2 mms. were
This compound was extremely unsaturated but because
no solid bromide in either a CC14 solution or acetic acid
solution could be obtained, further work along these lines
was abandoned*
It would appear that this compound might have
been a hydrocarbon, probably the same as the one obtained
from HaS04 treatment of the alcohol and isomeric with the
2-methyl cymene, namely 2-methylene para menthadiene*
Oxidation of alcohol from Condensation with KMnO«.
The original structure of the alcohol obtained In the
condensation was thought to have a plnene skeleton*
proof of this, the oxidation of plnene to plnonlc acid was
carried out*
The most efficient method was that of Delepine,
using potassium permanganate In a buffered solution*
acid was readily obtained*
Accordingly, this procedure was
modified slightly In an attempt to obtain plnonlc acid from
the alcohol obtained from the condensation of plnene and
formaldehyde •
17 grams of the above alcohol, 65 grams of KMn04, 40
grams of water, 600 grams of crushed Ice and 19 grams of
(NH4 )sS04 are shaken by machine for four hours and then
allowed to stand*
The Mn08 was filtered off and washed four
times with 33 cc. of water*
The filtrate was extracted four
times with 20 cc* of chloroform and acidified with 16*6 cc*
of concentrated H9S04 In 30 cc* of water*
The acid solution
was then extracted 5 times with 20 cc* of chloroform*
chloroform extract only yielded a red yellow oil which could
not be made to crystallize*
Iodoform test*
The oil did show a positive
The failure to obtain plnonlc acid Is in
harmony with later findings which Indicate that the alcohol
Is more probably a member of the llmonene series*
The author wishes to thank Dr* Walter E*
Miller who was kind enough to determine
the absorption spectra of both camphor and
the solid ether*
-7 1 *
The plnene formaldehyde condensation In acetic acid
solution was reinvestigated and three different products
were isolated:
1* A solid with a characteristic camphoraceous
2* The ester of a monohydroxy alcohol— 'homopineol*
3* The ester of the corresponding glycol.
The isolation of the solid in large quantities could
only be accomplished through compound formation with
phenol, from which it is readily regenerated by treatment
with alkali*
Failure of this solid compound to form characteristic
carbonyl derivatives as well as Its failure to show
any carbonyl absorption, led to the postulation of its
probable structure as that of a cyclic ether*
The ether, designated as 2,6 camphane methylene ether was
oxidized to the corresponding lactone*
The alcohol, homopineol, obtained by saponification of
Its corresponding ester was reduced catalytically and
found to be a member of the dipentene series rather than
the plnene series*
The completely reduced homopineol was shown to be a
mono hydroxy primary alcohol by oxidation to the corres­
ponding aldehyde which was characterized by its semicarbazone*
-7 2 -
Neither the alcohol, homopineol nor its corresponding
glycol could be isomerized to the ether, 2,6 camphane
methylene ether■
The alcohol homopineol was both dehydrogenated and
isomerized by iodine to the corresponding aromatic
hydrocarbon, 1, 2 dimethyl 4 isopropyl benzene.
The aromatic hydrocarbon described above was characterized
by oxidation with dilute nitric acid to the corresponding
mono and dibasic acids•
-7 3
1* U.S. Patent Serial No. 551, 428 (1940); 542,001 (1940), J«T. Bitter
2. Lipp, Ann. 289. 173 (1896)
3* Laderiburg, Bar. 31, 286-9 (1898)
4* Kriewitz, Ber* 32, 57-60 (1899)
5* Genvresse, Compt. Rendue 138.
1228 (1904)
6* Langlois, A. de Chemie 11-12. 290 (1919)
7* Prins, Chem Weekblad 14. 932 (1917)
Chem. Weekblad 16. 1510 (1919)
Koninkijke Akad. van Weten. 22, No. 1-5, 51-6
8 . Freireich, Ph.D. Thesis, N. Y. U. (1939)
9* Tuck, Master*s Thesis, N. Y. TJ. (1936)
10. Wagner and Godlewskl, J.Russ. Phys. Chem. Soc. 29, 121(1897)
11* Ruzicka, Helv. Chim. Acta 1, 110 (1918)
12* Meerwein and Van Emster, Ber* 53, 1815 (1920)
13. Lipp, Ber. 53, 769 (1920)
14* Meerwein, Van Emster and Jansen, Ber* 55. 2500 (1922)
15* Meerwein and Wortmann, Ann* 435. 190 (1924)
16. Meerwein and Montfort, Ann* 435. 207 (1924)
17. Nametkln, Ann. 432. 207 (1923)
18. Nametkln and Bruysova, Ann. 459. 144-71 (1927)
19. Simonsmsen, The Terpenes vol. II, 1932 Cambridge TJnlv* Press
20. Charlton and Day, Ind. and Eng. Chem. 29. 92-5 (1937)
21. Treibs, Ber 70, 589-94 (1937)
22. Acharya and Wheeler, J.Univ. Bombay 6,Pt. II, 134-5 (1937)
23* Kruwata, J.Soc.Chem.Ind. Japan 39 (suppl. bind.) 392-4(1936)
-7 4 -
24* Akiyoshl, Repts. Imp. Ind. Res. Inst. Osaka, Japan
17 No. 11, 1-116 (1937)
25. Imoto, J.Soc.Chem. Ind. Japan 41. 209-10, 11-12 (1938)
26* Hlrao and Takano, J. Chem. Soc. Japan 59, 95-101 (1938)
27. Whitmore and Church, J.A.C.S. 54, 3710-14 (1932)
28. Beilsteln, Handbuch Der Organ. Chem. Vol. VII pg. 110
Berlin (1925)
29. Baeyer and Vllliger, Ber. 34, 1206 (1901)
30. Aschan, Ber. 61, 38 (1928)
31. Houben and Pfankuch, Ber. 59. 2285 (1926)
32. Lipp, Ber. 56, 2098 (1923)
33. Simonsen, The Terpenes vol. I, Cambr. Univ. Press pg« 262(1932)
34. Ruzicka, Meyer and Mingazzinl, Helv. Chim. Acta, 5,356(1922)
35. Baeyer and Villiger Ber. 31, 1401 (1898)
36. Klages and Sommer, Ber. 39, 2311 (1906)
37. Ibida
38. Kyker and Bost, J.A.C.S* 61, 2469 (1939)
39. Bentley and Perkin, J.C.S. 71. 157-
40. Harries and Adams, Ber. 49, 1034 (1916)
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