karbamate

Karbamate (commonly spelled carbamate) refers to a class of organic compounds that contain the carbamate functional group, generally written as R-O-CO-NR'R''. The group consists of a carbonyl attached to both an alkoxy substituent (an OR' group) and an amide-type nitrogen (NR'R''). Carbamates are distinct from carbonates, which lack the amide nitrogen.

There are two main forms: alkyl or aryl carbamates, in which the alkoxy group is bound to the carbonyl; and N-substituted carbamates (urethanes), where the nitrogen bears substituents. In addition to being present as discrete molecules, carbamates arise as derivatives of carbamic acid.

In organic synthesis, carbamates are versatile. They are widely used as protective groups for amines; tert-butyloxycarbonyl (Boc) and benzyloxycarbonyl (Cbz) groups are common examples. They can be prepared by carbonylating alcohols or amines or by reaction of amines with carbonylating reagents such as phosgene or carbonyl diimidazole, followed by appropriate substitution.

Carbamates have important practical applications. A variety of carbamate pesticides inhibit acetylcholinesterase and are used in agriculture. Examples include carbaryl, carbofuran, and methomyl. In industry, carbamate chemistry underpins polyurethane production, where diisocyanates react with polyols to form urethane linkages. The urethane family is sometimes described as N- or O-substituted carbamates.

Chemically, carbamates hydrolyze to give amines and carbon dioxide, under acidic or basic conditions, depending on the structure. Environmental and health effects vary widely among members; some are tightly regulated due to toxicity concerns.