Thiocarbamate



In organic chemistry, thiocarbamates (thiourethanes) are a family of organosulfur compounds. As the prefix thio- suggests, they are sulfur analogues of carbamates. There are two isomeric forms of thiocarbamates: O-thiocarbamates, ROC(\dS)NR2 (esters), and S-thiocarbamates, RSC(\dO)NR2 (thioesters).

Synthesis
Thiocarbamates can be synthesised by the reaction of water or alcohols upon thiocyanates (Riemschneider thiocarbamate synthesis):


 * RSCN + H2O → RSC(=O)NH2
 * RSCN + R'OH → RSC(=O)NR'H

Similar reactions are seen between alcohols and thiocarbamoyl chlorides such as dimethylthiocarbamoyl chloride; as well as between thiols and cyanates. The herbicide Cycloate is produced in this way:
 * C6H11(C2H5)NCOCl + C2H5SH  ->  C6H11(C2H5)NCOSC2H5  +  HCl

Other related thiocarbamate herbicides include vernolate (C3H7)2NCOSC3H7 and triallate ((i\sC3H7)2NCOSCH2CCl\dCCl2.

Salts of thiocarbamate arise by the reaction of amines with carbonyl sulfide:
 * 2 R2NH + COS  →  [R2NH2+][R2N\sCOS−]

Reactions
In the Newman-Kwart rearrangement O-thiocarbamates can isomerise to S-thiocarbamates. This reaction, which generally requires high temperatures, is an important method for the synthesis of thiophenols.



Occurrence
Goitrin is a cyclic thiocarbamate found in some vegetables.