Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to a method or the
transesterification of esters of -thiocarbamic acids, -
having the formula :
X - A - NH - C -- S - R
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wherein R is methyl radical and A is phenyl radical,
whereas X is hydrogen or one or more Cl to C10 alkyl
or -NH-CO-SR groups.
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he existence cf these esters is known,
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and they are obtained, in the main, both by reacting ~ -
h ~ an isocyanate with a mercaptan, and by reacting an
amine with a chlorothiocarbonate, or also according
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to the reaction which forms the subject-matter of a
copending patent application by the same~applicant.
It has now been found that it is possible
to subject these compounds to appropriate transeste-
rlficatlon reactions so as to obtain valuable products,
whioh are very important for applications in the
industrial field.
As a matter of fact, the subject matter of
the present invention is the reaction between said es-
ters and compounds of the formula R' (X'H)n wherein X'
is O, S, or NH; R' is C2 to C10 alkyl or phenyl radical
and n is l to 5. The reaction in question is preferably
carried out in organic solvents at temperatures ranging ,~
from 50C to the boiling point temperature of the solvent.
It is also possible to employ a not too
strong nitrogen stream in order to remove from the reaction
environment the evolved mercaptan. The reaction can be
carried out in the presence o a catalytic system which
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76131
~ can be composed by a ter-tiary amine, more particularly
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the diazobicyclooc~ane (DABCO).
In order to afford a better understanding
of the present invention, a few explanatory examples
of the invention are set forth, which are by no wise
limiting of same.
EXAMPLE
A flask egoipped with a condenser is charged with
1.68 grams of S-methylthiocarbanylate (10 millimols),
0.88 grams of norbutylamine (12 millimols) and 10 mls.
of ben~ene. The mixture is heated until obtaining a
vigorous refluxing of the solvent while concurrently
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maintaining a stream of an inert gas in the reactor.
The evolved gas is passed through a trap which is cooled
to -78C. After one hour, 9.5 millimols of methyl
mercaptan are recovered from the trap. From the reaction
solution, by evaporation of the solvent; there are
` isolated 1.90 grams of N,N'-(norbutyl, phenyl) urea.
Yield : 99~-
EXAMPLE 2
~; A flask equipped wi-th a condenser is charged with
1.68 grams of S-methylthiocarbanylate (10 millimols),
1.12 grams of aniline (12 millimols) and 10 mls. of
xylene. The mixture is heated until maintaining a
vigorous reflux of the solvent while concurrently
maintaining a s-tream of an inert gas in the reactor.
The evolved gas is passed through a -trap cooled to
-78C. After one hour there are recovered in the trap
9.4 millimols of methyl mercaptan. From the reaction
solution there are isolated by filtration 2.0 grams
of N, N'-biphenylurea. Yield 95~
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- 10~6131
E~LE 3
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flask equipped wi-th condenser is charged with
1.68 grams of S-methylthiocarbanylate (10 millimols),
0.89 grams of norbutanol (12 millimols), 0.10 grams of
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diazobicyclooctane and 10 mls. of toluene. The mixture
is heated until obtaining a vigorous reflux of the sol-
vent while concurrently maintaining a stream of inert
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gas in the reactor. The evolved gas is passed through
a trap which is cooled to -78C. After two hours there -
are recovered in the trap 9.8 millimols of methyl mer- -~
captan. Erom the reaction solution, by evaporation of
the solvent, and recrystallization of the residue from
benzene-ether, there are isolated 1.85 grams of nor.butyl
carbanylate. Yield 86%.
EXAMPLE 4
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A flask equipped with condenser is charged with 1.68
grams of S-methylthiocarbanylate (10 millimols), 1.13 grams
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of phenol (12 millimols), 0.10 grams of diazobicyclooctane ~-
and 10 mls. of xylene. The mixture is heated until obtai-
ning a vigorous reflux of the solvent while concurrently
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maintaining a stream of inert gas in the reactor. The
evolved gas is passed throuyh a trap which is cooled to ;- -
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-78C. After two hours there are recovered in the trap
9.9 millimols of methyl mercaptan. sy addiny petroleum
ether to the reaction solution, 2.03 grams of phenyl-
carbanylate are crystallized. Yield 95~.
E~MP$E 5 , ' ~".':' '
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- With exactly the same procedure as in Example 4, by reacting
1.68 grams of S-methylthiocarbanylate, 1.3 yrams of thiophenol
an~ 0.10 yrams of diazobicyc~octane in 10 mls toluene, 1.85 grams
of S-phenylthiocarbanylate have been obtained. Yield 80~
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EXAMPLE 6
A flask equipped with condenser is charged with 1.35
grams of toluene-2:4-dithiocarbamic acid S,S'-dimethylester
(5 millimols), 1.4 grams of nor.heptanol (12 millimols),
0.10 grams of diazobicyclooctane and 20 mls. of xylene. The
mixture is heated while concurrently maintaining a stream
of an inert gas in the reactor. The evolved gas is passed
through a trap which is cooled to -78C. After one hour
9.4 millimols of methylmercaptan are recovered in -the
trap. The slightly cloudy solution is filtered and evapo-
rated to one-fourth of its initial volume. By addition
of petroleum ether and cooling to 0C, 1.4 grams of toluene-
2:44-dicarbamic acid-dieptylester crystallizes. Yield 70%.
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EXAMPLE 7
A flask equipped with condenser is charged with 1.35
grams of toluene-2:4-dithiocarhamic acid - S,S'~dimethylester
(5 millimols), 0.94 grams of phenol (10 millimols), 0.10
grams of diazoblcyclooctane and 20 mls of xylene. Thé mix-
ture is heated until maintaining a vigorous refluxing of
the solvent, while concurrently~passing a stream of nitrogen
through the reactor. The evolved gas is forwarded to a
trap which is cooled to -78C. After 1.5 hours there are
recovered in the trap 9.5 millimols of methyl mercaptan.
By cooling the reaction solution there are isolated 1.8
grams of toluene-2:4-dicarbamic acid-diphenyl ester.
Yield 99~.
All of the compounds as obtained in the preceding
Examples have been identified by comparison with samples ~'
as obtained from conventional synthesis. ~
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76~31
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EXAMPLE 8
A flask equipped with condenser is charged with
, 1.35 grams of toluene-2:4-dithiocarbamic acid - S,S'-
dimethyl ester (5 millimols~, 0.38 grams of propylene-1:2-
glycol (5 millimols), 0.08 grams of diazobicyclooctane
and 20 mls. of xylene. The mix~ure is heated until
obtaining a vigorous reflux of the solvent while concur-
rently maintaining a stream of an inert gas in -the reactor.
; The evolved gas is passed through a trap cooled to -78C.
After one hour, there are recovered in the trap 9.3 milli~
mols of methyl mercaptan. Once the solvent has been ~ ~ ;
removed by filtration, -there are recovered 1.5 grams of
solid product. The I.R. spectrum in KBr exhibits the -
following characteristic absorptions of urethan (3 microns;
5.8 microns). The polymer shows at the differential
thermal analysis a vitreous transition (Tgj at 60C.
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