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2,464,430
Patented Mar. 15, 1949
UNITED STATES PATENT OFFICE
2,464,430
PRODUCTION OF FORMALS 0F
PENTAERYTHRITOL
Robert H. Barth, Ridgewood, and John E. Snow,
Hasbrouck Heights, N. J., assignors to Heyden
Chemical Corporation, New York, N. Y., a cor
poration of Delaware
No Drawing. Original application January 12,
1944, Serial No. 517,990. Divided and this ap
plication October 10, 1945, Serial No. 621,588
8 Claims. (01. 260-338)
1
2
This invention relates to the isolation and con
production, either (1) by azeotropic dehydration
version of byproducts consisting of formals ob
tained in the preparation of pentaerythritol and
by crystallization ‘or (2) by acetylation of the
ethers of pentaerythritol by the reaction of ac
etaldehyde, formaldehyde and alkali. In one of
its more speci?c aspects the invention relates to.
a process for the conversion of one such formal,
namely, formaldehyde bipentaerythrityl acetal,
to pentaerythritol and pentaerythritol cyclic
monoformal.
The present application is a division of appli
cation Serial No. 517,990, ?led January 12, 1944,
by Robert H. Barth, Toivo R. Aalto, John E.
Snow and Hilding R. Johnson, which Was aban
of said liquors with benzene or toluene followed
end liquors and distillation of the resulting di- ,
acetate therefrom; the resulting diacetate is
thereafter hydrolyzed to produce pentaerythritol
cyclic monoformal. When substantially pure,
pentaerythritol cyclic monoformal has a melting
point of 55° to 60° C‘. (Reported melting point
is 60° C.)
It is an object of the present invention to pro
vide a process for the production of pentaerythri
tol cyclic monoformal.
Another object of the invention is to provide a
doned after ?ling of this application.
15 process for the extraction of formaldehyde bi
pentaerythrityl acetal, a compound not hereto
In the production of pentaerythritol and its
fore described, from pentaerythritol process end
ethers, dipentaerythritol and tripentaerythritol,
liquors.
there are formed at least two other compounds,
A further and more speci?c object of the pres
one of which has not heretofore been identi?ed
or disclosed. Both of these compounds are for 20 ent invention is to provide a process for the con
version of formaldehyde bipentaerythrityl ac
mals, one of which, formaldehyde bipentaerythri
tyl acetal, melts at 125° C. to 140° C. when practi
cally free from pentaerythritol. When freed
nearly entirely from pentaerythritol, it melts at
etal to pentaerythritol cyclic monoformal.
Other objects of the present invention, some
of which are referred to more speci?cally here
125° C. to 135° C. It is soluble in water in all 25 inafter, will be apparent to those skilled in the
art to which the present invention pertains.
proportions, being salted out of solution by the
We have discovered that formaldehyde bi
sodium formate which is usually present in the
pentaerythrityl acetal can be isolated from tech
reaction liquor. It occurs as a component of
nical pentaerythritol by extraction with n-pro
technical pentaerythritol along with dipentae
rythritol. From carbon and hydrogen determina 30 panol, isopropanol, butyl acetate, or other or
ganic solvents in which it is soluble and in which
tions, and from the hydroxyl values, molecular
neither pentaerythritol nor dipentaerythritol is
weights, and saponi?cation values, both of the
appreciably soluble. Technical pentaerythritol
compound and of its hexaacetate, this compound
can be puri?ed by recrystallization from water
is the formaldehyde bipentaerythrityl acetal hav
ing the formula:
35 and by separation in a centrifugal separator, as
011,011
omon
Hoonz-éi-onz-o-cnfo-cnz-t-omon
E2011
E2011
described in the now abandoned application of
Blythe M. Reynolds, Serial No. 483,938, ?led April
21, 1943; from the ?ltrate or mother liquor which
results from the separation of monopentaerythri
Throughout this speci?cation and in the claims 40 tol from dipentaerythritol in such process, form
aldehyde bipentaerythrityl acetal can be re
this linear formal of pentaerythritol, which has
not been heretofore described, will be referred to
covered.
'
We have also discovered that formaldehyde bi
as formaldehyde bipentaerythrityl acetal. '
pentaerythrityl acetal can be converted to pen
The second of the two compounds which are
present in the reaction liquor obtained in the 45 taerythritol cyclic monoformal by reaction with
acidic reagents such as aqueous hydrochloric
production of pentaerythritol and ethers of pen
taerythritol, is pentaerythritol cyclic monofor
acid.
7
We have further discovered that pentaerythri
tol cyclic monoformal may be recovered from end
HOHZG
GET-O
\ /
50 liquors resulting from the process of producing
pentaerythritol by extraction with ethyl acetate.
We have further discovered that either of
‘these formals can be converted into penta
This compound, which was disclosed by Skrabal
erythritol and formaldehyde by. heating them
and Kalpasanoff in Berichte, 1927, vol, 613, pages
55 to 57, is very difficult to crystallize. It may be 55 with dilute aqueous hydrochloric or sulfuric acid.
The formaldehyde that is formed may be removed
obtained from the end liquors of pentaerythritol
mal, which has the formula:
Homo/ \om-o/
2,464, 4'30
3
4
by distillation. Since the distillation requires a
rather long period of time, it is convenient to
hydrolyze the formal in the presence of a nitro
gen compound such as phenylhydrazine, 2,4-di
Examples of methods of practicing the inven
tion are illustrated in the examples which follow
hereinafter.
Example‘ 1.—-Isolatz'on of formaldehyde
bipentaeryih'rityl acetal
nitrophenylhydrazine, urea, or ammonium sul
fate, to form pentaerythritol and respectively,
When technical pentaerythritol is crystallized
a hydrazone, methylene urea or hexamethyene
once from an equal weight of water, it is found
that 12 to 14% of the material is soluble at 25° C.
tetramine, as described in Example 8 hereinafter,
The pentaerythritol can be recovered from the
10 The calculated solubility, based on the respective
reaction products.
solubilities of the mono and dipentaerythritol
that are present, is about 8%. The remainder
The reactions of these formals with an aqueous
mineral acid can be written as follows:
(1)
CHZOH
CHEOH
Mineral
01
HO CH2—C—CH2—O—CHz—O—CH2-—C—CH2OH
0 E2013
E2011
above, containing 12 to 14% of dissolved material
is evaporated to dryness and boiled up with 10
times its weight of n-propanol, the formaldehyde
bipentaerythrityl acetal goes into solution in the
n-propanol. Since pentaerythritol is only slight
9
"0 ly soluble in n-propanol, a separation of the two
is thereby effected. Upon concentration and
2
Formaldehyde bipentaerythrityl acetal
CHQOH
O—CH2 CHZOH
HOCHg-C—CH2OH + 0E2
H2011
Pentaerythritol
C\
O~0é2
appears to be the formaldehyde bipentaerythrityl
acetal described hereinabove. When a mother
15 liquor or ?ltrate, such as that described herein
CHZOH
Pentaerythritol cyclic
monoformal
chilling, fairly pure formaldehyde bipentaery
thrityl acetal crystallizes out. This may be fur
(2)
O—CHZ
CHZOH
Mineral
1
Acid
C\2
C\
+ H20 —-—>
O-Céz CHzOH
H O 0 Hz
0 H2O +
05
ther puri?ed by recrystallization from 1,4
"'
dioxane.
Example 2.—Is0lati0n of formaldehyde
C H2 0 H
bipeniaerythrityl acetal
One hundred (100) parts of technical penta
/C
H O C Hz
0 H2 0 H 30
Two new acetates have been prepared from
these formals. One is the hexaacetate of form
erythritol containing formaldehyde bipenta
erythrityl acetal are mixed with 100 parts of n
butyl acetate and the mixture boiled for one hour.
aldehyde bipentaerythrityl acetal, having the
following formula:
Approximately three (3) parts of formaldehyde
bipentaerythrityl acetal are extracted. The
formaldehyde bipentaerythrityl acetal can be
separated by ?ltering o? the pentaerythritol and
concentrating and cooling the n-butyl acetate
solution so as to crystallize out the formaldehyde
bipentaerythrityl acetal.
Example 3.—-Isolatz‘on of pe'ntaerythritol cyclic
monoformal and conversion to the diacetate
The end liquors obtained from the process of
producing pentaerythritol were extracted with
The other is the diacetate of lpentaerythritol
cyclic monof-olrmal, having the following formula:
ethyl acetate, and the ethyl acetate separated
from the extract by evaporation. A syrup re
oH3-<|3—o-oH2 CHz—O
mains which contains a small amount of water
CB2
and sodium formate and probably some .penta
erythritol. This syrup has a hydroxyl value of
0 about 28% and a molecular weight of about 150
and is substantially pure pentaerythritol cyclic
Results of determinations of molecular weights
and ultimate analyses of the formals and acetates
monoformal.
are given in the following tables:
Twenty-‘?ve (25) parts of this syrup were re‘
Table I .--Formals
Found
0
_
Per cent
Formaldehyde bipentaerythrityl acetal.
46. 1
Pentaerythritol cyclic monoformal..."
46. 9
Calculated ‘
>
H
OH
Per cent
9. 03
8. 86
Per cent
38
25. 1
M01.
wt’
278
149
7
0
H
Per‘ cent,
46; 5
48. 6
Per cent
8.45
8. 12
OH
Per ce‘nl
36. 0
23. 0'
M01.
Wt.
284
148
Table II.—Acetates
Found
Hexaacetate of formaldehyde bipentaetal
1 Saponi?catioii value.
Calculated
SapJ
Mol.
0
H
Value
Wt.
Per cent
Per cent
Per cent
51. 5
7.15
11. 34
492
51. 5
6; 72 _
51. 2
7. 4s
v 8.56
251
51.7‘
a. 90
Sap.1
O
H
Value
Per cent
Per cent
Per cent
l1. 2
8.62
M01.
Wt.
536
232
935594303
acted with 54 parts of acetic anhydride. .When-P.
the acetylation was complete, the excessacetic
anhydride and the liberated acetic acid were re-:
moved by distillation under reduced pressure.
The remaining material weighed 40.5 parts and
had a saponi?cation value of 9.2 cc. of'normal.
sodium hydroxide solution per gram. This
acetylated product was subjected to vacuum dis-‘
tillation and the fraction which distilled at 117
to 140° C. at a pressure of 0.4 mm. of mercury
iiiixExa'mple 6) were treated with 25 parts of acetic
anhydride. When acetylation was completed, the
excess acetic anhydride and the liberated acetic
acid were removed by evaporation under reduced
pressure. The residue was distilled under reduced
pressure and boiled at 100 to 111° C. at a ‘pressure
of 0.6 mm. of mercury. The distilled fraction was
essentially pure pentaerythritol cyclic monofor-.
mal diacetate.
Example 8—Reactz'on of formaldehyde bipenta
represented about 60% of the starting material.
erythrityl acetal with a hydrazine
This distilled material is substantially ‘penta
To
one
part of formaldehyde bipentaerythrityl
erythritol cyclic monoformal diacetate, which
acetal was added 50 parts of water, 50 parts of
was con?rmed also by molecular weight deter
mlnations and saponi?cation values. Another 15 methanol, and a solution containing 1.4 parts of
2,4-dinitrophenylhydrazine which is 100% excess
sample of the diacetate had a boiling point of
hydrazine over that required for combining with
110° to 111° C. at a pressure of 0.6mm. (EX-U
all the formaldehyde that is theoretically formed
ample '7).
in the reaction. Ten (10) parts of 35% hydro
Example 4.—Puri?cation, of crude pentaerythritol
cyclic mo'noformal
Crude pentaerythritol cyclic monoformal ‘is,
puri?ed in the following way: One (1) part of;
crude material is heated with 20 parts of benzene,
using a trap built into a re?ux condenser so that
any water present can be removed azeotropically.l-_
The anhydrous, hot benzene solution is ?ltered so,
as to remove any sodium formate that is present.
Upon cooling the benzene solution, the puri?ed
pentaerythritol cyclic monoformal crystallizes
out and may be recovered by ?ltration. Care
must be taken to eliminate moisture, as pentaq
chloric acid was added, and the mixture boiled
under reflux for 2 hours. Upon cooling the mix
ture, a ?occulent, orange brown solid settled out.
It was the 2,4-dinitrophenylhydrazone of formal
dehyde. The pentaerythritol can be recovered
from the remaining solution after the removal of
the hydrazone by ?ltration.
_ Pentaerythritol and formaldehyde can be pre
pared by boiling or heating formaldehyde bi
pentaerythrityl acetal and pentaerythritol cyclic
monoformal with aqueous mineral acids such as
sulfuric acid and hydrochloric acid, as described
hereinbefore. The formaldehyde can be distilled
from the reaction mixture and the pentaerythri
erythritol cyclic monoformal is extremely hygroy
.tol recovered from the residue. If desired, the
scopic.
35; boiling may be conducted in the presence of a
Example 5.—Preparation of hexaacetate of
nitrogen compound such as phenylhydrazine, 2,4
formaldehyde bipentaerythrityl acetal
dinitrophenylhydrazine, urea or ammonium sul
The hexaacetate of formaldehyde bipentai
fate, which will react with the liberated formalde
erythrityl acetal is prepared by acetylation of 15
hyde.
These reactions may be used as bases of
parts of the acetal with 55 parts of acetic an 40 analytical methods for determination of the pro
hydride. This mixture is heated to 95° C., and
portion of formaldehyde bipentaerythritol acetal
then the excess acetic anhydride and the liberated
or pentaerythritol cyclic monoformal, for ex
acetic acid are removed by vacuum distillation.
ample, in substantially pure products, in techni
The residue is a crystalline, waxy solid consisting:
cal pentaerythritol, or in pentaerythritol process
essentially of formaldehyde bipentaerythrityl . ~ end liquors. The liberated formaldehyde may be
acetal hexaacetate.
determined in conventional manner and the pro
portions of these formals calculated therefrom,
Example 6.—Preparation of pentaerythritol'cyclic
or the formaldehyde may be precipitated with 2,4
monoformal by hydrolysis of formaldehyde
bipentaerythrityl acetal
-
A solution of 50 parts of formaldehyde bipenta
dinitrophenylhydrazine and the resulting hydra
5.0 zone weighed.
Inasmuch as the foregoing speci?cation com
erythrityl acetal (isolated as described in Ex
prises preferred embodiments of the invention it
amples 1 or 2, for example) in 100 parts of 10%
is to be understood that the invention is not lim
hydrochloric acid was boiled under re?ux for 2
ited thereto and that modi?cations and variations
hours. It was neutralized with 58 parts of a 10%
sodium hydroxide solution and the mixture was 55 may be made therein without departing substan
tially from the scope of the appended claims.
evaporated to a paste under reduced pressure.
Having thus described our invention what we
This paste was treated with an equal weight of
isopropanol and the solids which separated out
claim as new and desire to secure by Letters Pat
ent is:
1. A process for the production of pentaeryth
dryness and the residue was taken up in 180 parts 60
ritol cyclic monoformal which comprises the
of isopropanol. A new crop of crystals was re
extraction of formaldehyde bipentaerythrityl ace
moved. The two solid crystalline fractions had
tal from a mixture containing said compound to
a combined weight of 42.2 parts, and consisted
gether with pentaerythritol and dipentaerythritol
essentially of pentaerythritol mixed with some
sodium chloride. The ?ltrate from the second 65 in substantially anhydrous form with a solvent
selected from the group consisting of n-propanol,
crystallization was evaporated to dryness. The
were ?ltered off.
The ?ltrate was evaporated to
.of 25.0%, and which crystallized on long stand
me. This material was impure pentaerythritol
isopropanol and butyl acetate, recovering formal
dehyde bipentaerythrityl acetal from the extract
and thereafter heating said formaldehyde bi
monoformal to the diacetate
rityl acetal is converted to pentaerythritol cy
product was a syrup which had a, hydroxyl value
70 pentaerythrityl acetal with such an amount of a
cyclic monoformal.
mineral acid and at such temperature and for
Example 7—C'omrersz'0n of pentaerythritol cyclic
such period that the formaldehyde bipentaeryth
Eight (8) parts of crude pentaerythritol cyclic
clic monoformal, separating any pentaerythritol
monoformal (obtained, for example, as described 75 which was formed in the reaction, and thereafter
7
recovering pentaerythritol cyclic monoformal
from the remaining products.
8.
hipentaerythrityl acetal from a mixture‘contain
from a mixture containing said compound to~>
ing: said compound together with pentaerythritol
and dipentaerythritol, which comprises extractingv
acid mixture in substantially anhydrous form with
n-propanol, and recovering formaldehyde bipen
taerythrityl acetal from the extract.
gether with pentaerythritol and dipentaerythritol
in substantially anhydrous form with n-propanol,
recovering formaldehyde bipentaerythrityl acetal
bipentaerythrityl acetal from a mixture contain
ing said compound together with pentaerythritol
2. A process for the production of pentaerythri~
tol cyclic monoformal which comprises the ex-'
traction of formaldehyde bipentaerythrityl acetal
6. A process for the separation of formaldehyde
from the extract and thereafter heating said for-' 10 andrdipentaerythritol, which comprises extract
maldehyde bipentaerythrityl acetal together with‘
approximately 100 parts by weight of 10% hydro
chloric acid for a period of approximately 2 hours,
neutralizing the resulting mixture with sodium‘
hydroxide and evaporating the mixture to sub
stantial dryness, extracting the substantially dry
ing said mixture in substantially anhydrous form
with butyl acetate, and recovering formaldehyde
bipentaerythrityl acetal from the extract.
7. A process for the production of pentaeryth-'
I ri‘tyl cyclic monoformal, which comprises heating
a mixture of formaldehyde bipentaerythrityl ace
mixture with isopropanol to separate the penta
tal with such an amount of a mineral acid and
erythritol cyclic monoformal from pentaerythritol‘
at such temperature and for such period that
and sodium chloride, and subsequently recover~
the formaldehyde bipentaerythrityl acetal is con-7
ing pentaerythritol cyclic monoformal from the 20 verted to pentaerythritol cyclic monoformal, sep
isopropanol extract.
arating any pentaerythritol which was formed in
3. A process for the production of pentaerythri~
the reaction, and thereafter recovering pentae
tol cyclic monoformal which comprises the extrac
rythritol cyclic monoformal from the remainingv
tion of formaldehyde bipentaerythrityl acetal
products.
from a mixture containing said compound togeth.
8. A process for the production of pentaerythe
er with pentaerythritol and dipentaerythritol in
I ritol cyclic monoformal, which comprises heating
substantially anhydrous form with butyl acetate,
under gentle re?ux approximately 50 parts by
recovering formaldehyde bipentaerythrityi acetal
- weight of formaldehyde bipentaerythrityl acetal
from the extract and thereafter heating said form
together with approximately 100 parts by weight
aldehyde bipentaerythrityl acetal together with 30' of 10% hydrochloric acid for a period of approxi
approximately 100 parts by weight of 10% hydro‘
mately 2 hours, neutralizing the resulting mixture
chloric acid for a period of approximately 2 hours,
with sodium hydroxide and evaporating the mix
neutralizing the resulting mixture with sodium
ture to substantial dryness, extracting the sub~
hydroxide and evaporating the mixture to sub
stantially dry mixture with isopropanol to sepa
stantial dryness, extracting the substantially dry .
rate the pentaerythritol cyclic monoformal from
mixture with isopropanol to separate the pentae
pentaerythritol and sodium chloride, and subse
rythritol cyclic monoformal from pentaerythritol'
quently recovering pentaerythritol cyclic mono
and sodium chloride, and subsequently recovera
formal from the isopropanol extract.
ing pentaerythritol cyclic monoformal from the
ROBERT H. BARTH.
isopropanol extract.
-
JOHN
SNOW.
4. A process for the separation of formaldehyde
bipentaerythrityl acetal from a mixture contain“
ing said compound together with pentaerythritol
and dipentaerythritol, which comprises extracting.
REFERENCES CITED
The following references are of record in the
I‘ ?le of this patent:
~
said mixture in substantially anhydrous form with 45,
UNITED STATES‘ PATENTS
a solvent selected from the group consisting of
n-propanol, isopropanol and butyl acetate, and‘
Number
Name
Date
recovering formaldehyde bipentaerythrityl acetal
from the extract.
5. A process for the separation of formaldehyde 50
2,223,421
Hubacher et a1. ____ __ Dec. 3, 1940
' 2,270,839
Wyler ____________ __ Jan. 30, 1942
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