Method for producing thiochloroformates

Details Method for producing thiochloroformates Method for producing thiochloroformates

2000-02-17

2000-12-19

Ambrose, Michael G.

Organic compounds -- part of the class 532-570 series

Organic compounds

Esters having the thiocarboxylate group, -cx-, wherein the...

558257, C07C32722, C07C32720

Patent

active

061629391

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a process for preparing thiochloroformates by reacting thiols with phosgene in the presence of a catalyst.
Thiochloroformates are important intermediates in organic synthesis, in particular of physiological active substances such as drugs and crop protection agents. Thiochloroformates are obtained by reacting thiols with phosgene in a process which has been known for a long time. Since the reaction of thiols with phosgene takes place very slowly and with considerable formation of byproducts such as thiocarbonates and disulfides, it is normally carried out in the presence of catalysts.
U.S. Pat. No. 3,299,114 discloses the preparation of thiochloroformates by phosgenation of the corresponding thiols (mercaptans), using as catalysts open-chain or heterocyclic tertiary amines or heterocyclic aromatic nitrogen bases of the pyridine type. However, the yields of thiochloroformates obtained thereby are unsatisfactory.
EP-A 0 024 683 and EP-A 0 053 981 propose carboxamides and acyclic ureas as catalysts. The disadvantages of these processes are that the yields are still unsatisfactory, the amount of byproducts is high, and the catalyst content of the mixtures from the synthesis is high. It is therefore necessary for the thiochloroformates which have been formed to be worked up in another process step, as a rule by distillation.
DE-A 41 37 012 discloses organic phosphorus compounds as catalysts for preparing thiochloroformates. The disadvantage of these processes is that distillation residues containing phosphorus are produced and are difficult to dispose of because of the formation of phosphonic acids on incineration.
It is an object of the present invention to remedy the abovementioned disadvantages, in particular to provide a process for preparing thiochloroformates, which makes do with very small amounts of catalyst and substantially avoids the formation of byproducts.
We have found that this object is achieved by a process for preparing thiochloroformates from thiols by reaction with phosgene (phosgenation) in the presence of a catalyst, wherein a cyclic urea or thiourea is used as catalyst. By cyclic ureas or thioureas are meant those compounds in which the urea or thiourea moiety is part of a ring system. The cyclic urea or thiourea may be present either as such or in the form of its salts which are obtainable by reaction with hydrohalic acids or phosgene.
Cyclic ureas or thioureas are known per se. Their preparation is described, for example, in Houben-Weyl, Methoden der organischen Chemie, Volume E4, 4th edition, 1983. formula I: ##STR1## where
X is an oxygen or sulfur atom,
Y is a saturated of mono- or polyolefinically unsaturated carbon chain which has 2 to 8 carbon atoms and which is unsubstituted or mono- to trisubstituted by C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, C.sub.2 -C.sub.4 -acyl, C.sub.2 -C.sub.4 -acyloxy, phenoxy, C.sub.2 -C.sub.8 -dialkylamino, halogen, nitro and cyano and which may contain an ether, thioether, tertiary amino, keto, lactone, alkyl-substituted lactam, sulfone or diketo moiety, or is a cycloalkylene having 5 to 12 carbon atoms, heterocycloalkylene group having 4 to 11 carbon atoms, arylene group having 6 to 12 carbon atoms or hetarylene group having 3 to 11 carbon atoms, each of which is unsubstituted or mono- to trisubstituted by C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, phenoxy, C.sub.2 -C.sub.4 -acyl, C.sub.2 -C.sub.4 -acyloxy, C.sub.2 -C.sub.8 -dialkylamino, halogen, nitro and/or cyano, and
R.sup.1 and R.sup.2, which may be identical or different, are C.sub.1 -C.sub.20 -alkyl, C.sub.2 -C.sub.20 -alkenyl or C.sub.2 -C.sub.20 -alkynyl, each of which is unsubstituted or mono- to trisubstituted by C.sub.1 -C.sub.4 -alkoxy, C.sub.2 -C.sub.4 -acyl, C.sub.2 -C.sub.4 -acyloxy, C.sub.2 -C.sub.8 -dialkylamino, halogen, nitro and/or cyano, or is C.sub.2 -C.sub.20 -acyl or is C.sub.3 -C.sub.8 -cycloalkyl, C.sub.4 -C.sub.20 -cycloalkylalkyl, C.sub.3 -C.sub.8 -hetero cycloalkyl, C.sub.4 -C.sub.20 -heterocycloalkylalkyl, C.sub.6 -C.sub.14 -ary

REFERENCES:
patent: 3277143 (1966-10-01), Tilles
patent: 4340746 (1982-07-01), Semler et al.
patent: 4400329 (1983-08-01), Deweerdt et al.

Affiliated with

Also associated with

Rating

Method for producing thiochloroformates does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method for producing thiochloroformates, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing thiochloroformates will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-272297