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, (esters), and S-thiocarbamates, (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:
Other related thiocarbamate herbicides include vernolate and triallate (.
Salts of thiocarbamate arise by the reaction of amines with carbonyl sulfide:
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.
Uses Thiocarbamate based herbicides (e.g. prosulfocarb) were introduced in 1957 and in 2017 was a $200,000,000 market. Other thiocarbamate herbicides are pebulate, molinate, EPTC, butylate, triallate, vernolate and cycloate.
See also Dithiocarbamate Carbamate Tolnaftate, a thiocarbamate used as an antifungal agent
References