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Preparation and Properties of Substances with N- or S-Perhalogenomethyl Groups.

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CONFERENCE REPORTS
Chemisorption of Gases on Evaporated
Metal Films
G. Wedler, Hannover (Germany)
Chemisorption of gases depends not only o n the chemical
composition of the adsorbing surface, but also to a great
extent on its structure and cleanliness. Extremely pure metal
surfaces suitable for chemisorption investigations can be
obtained by deposition of thin metal films at about 10-10 mm
Hg on degassed glass surfaces.
Electron-microscopic and X-ray studies with numerous
100-A-thick nickel films that had been condensed at 77 OK
and annealed at 60°C showed that these films consist of
crystals of approximately uniform size and oriented preferentially with the (111) face parallel to the underlying
surface. X-Ray measurements and also the mean free paths
of the conduction electrons (determined from the dependence
of resistivity on film thickness) show that these nickel films are
in a n ordered state. Adsorption phenomena observed o n such
films are thus characteristic of the compact catalyst material.
Chemisorption of gases was studied by simultaneous measurement of the change of electric resistance and work
function of the films, as well as by direct calorimetric measurement of differential heats of adsorption.
For the system nickel/hydrogen, in contrast to the report in
the literature that the heat of adsorption is strongly dependent
o n the coverage of the surface by hydrogen, we observed a
heat of adsorption of ca. 17.5 kcalimole independent of the
coverage, provided that lOO-A-thick, completely fresh nickel
films were used as adsorbent; only when a complete monomolecular layer had been built up did the heat of adsorption
decrease with increasing coverage. If the nickel films had
previously been covered with oxygen or carbon monoxide up
to about a quarter of a monolayer, then the heat of adsorption
of hydrogen - which was chemisorbed as atoms - amounted
t o ca. 21 kcallmole at the beginning of the experiment; the
heat of adsorption decreased in this case with increasing
coverage, in contrast to the behavior with initially fresh
films.
In contrast to the systems nickel/hydrogen and nickel/carbon
monoxide 111, with which substantially only chemisorption
occurs on the metal surface, we observed marked uptake of
hydrogen in the lattice, i.e. a volume effect, for the system
titanium/hydrogen [21. With the system nickel/water vapor 131
a reaction clearly occurs between the adsorbent and the
adsorbate, with formation of NiOH groups on the surface.
[Lecture at Erlangen (Germany)
[VB 14 IE]
o n May 13th, 19661
German version: Angew. Chem. 78, 827 (1966)
[l] G.Wedler and M . Fouad, Z . physik. Chem. N.F. 40, 1, 12
(1964).
[2] G.Wedler and H. Siroihenk, Ber. Bunsenges. physik. Chem.
70, 214 (1966); Z.physik. Chem. N.F. 48, 86 (1966).
[31 R . Suhrmann, J. M . Heras, L. Viscid0 de Heras, and G. Wedler, Ber. Bunsenges. physik. Chem. 68, 511, 990 (1964).
Preparation and Properties of Substances with
N- or S-PerhalogenomethylGroups
E. Klauke, Leverkusen (Germany)
Trichloromethanesulfenyl chloride, CI3C-SC1 ( I ) , is fluorinated selectively in anhydrous H F to dichlorofluoromethanesulfenyl chloride. Replacement of further chlorine
atoms by fluorine requires stronger fluorinating agents, e.g.
SbF3 or NaF. Whereas 3,6-dichloro-1,4,2,5-dithiadiazineis
formed o n treatment of ( I ) with NH3[1], dichlorofluoro-
848
and chlorodifluoro-methanesulfenyl chloride and ammonia
give the corresponding amides FC12C-SNH2, b.p. 54-56 "C/
50 mm Hg, and F2CIC-SNH2, b.p. 89SoC/760 mm, respectively.
Perhalogenomethyl arenethiosulfonates can be cleaved to
thiols with HCI. However, trichloromethanethiol decomposes
to phosgene with loss of HCI. Thiophosgene and other thiocarbonyl dihalides are also obtained by thermolysis of perhalogenomethyl thiosulfonates.
Ar-SO2S-CCI2F
+ HC1
+ Ar-SO2CI
+ FClzC-SH
Reaction products of ( I ) are of practical importance as leaf
fungicides. Replacement of the CC13 by the CC12F group
leads to preparations with appreciably broader activity
spectra [21.
o-(Trichloromethy1)phenyl isocyanate undergoes CI-F exchange in anhydrous H F ; isomerization occurs simultaneously and o-N-(trifluoromethy1)aminobenzoyl fluoride (2)
can be isolated.
N(Trifluoromethy1)aniline derivatives (3) are readily prepared from aromatic isocyanide dichlorides 131.
Ar-N=CC12
3
y
Ar-NH-CF3
(3)
3
Ar-N-C=N-Ar
I
(4)
F
In the preparation of N-(trifluoromethy1)anilines (3), fluoroformamidines, e.g. (4), are obtained as dimerization products
of the intermediate isocyanide difluorides, the amounts
varying according to the nature of the substitution and the
reaction conditions. N-(Trifluoromethy1)anilines (3) are
smoothly acylated by sulfenyl chlorides, but not by carbonyl
chlorides. Chlorocarbonyl isocyanide dichloride and HF give
trifluoromethyl isocyanate.
[VB 12 IE]
[Lecture at Gottingen on May 20th, 19661
German version: Angew. Chem. 78, 829 (1966)
[l] A. Senning, Angew. Chem. 75, 450 (1963); Angew. Chem.
internat. Edit. 2, 325 (1963).
[2] E. Kiihle, E . Klauke, and F. Grewe, Angew. Chem. 76, 807
(1964).
[3] H. Holischmidt, Angew. Chem. 74,848(1962);Angew. Chem.
internat. Edit. 1 , 632 (1964); E. Kiihle, Angew. Chem. 74, 861
(1962); Angew. Chem. internat. Edit. I , 647 (1964).
Types of Bonding of Sulfur in Vulcanization
Processes
W. Scheele, Hannover (Germany)
In vulcanization processes part of the sulfur is always bound
in polysulfide groups (Sp-sulfur). The amount of S,-sulfur
passes through a maximum during the process; later products
contain, inter alia, sulfide groups, predominantly as part of
five-membered rings either with or without double bonds.
The amount of S,-sulfur present in the vulcanizate after a
reaction time t can be expressed by the empirical equation (1) :
Angew. Chem. internat. Edit.
Vol. 5 (1966) 1 No. 9
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preparation, perhalogenomethyl, properties, substances, group
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