karbamates

Carbamates are a class of organic compounds that contain the carbamate functional group, derived from carbamic acid. The simplest members are alkyl esters of carbamic acid with the general formula ROC(=O)NH2, while many derivatives replace the amide hydrogen with alkyl or aryl groups to give N-substituted carbamates (ROC(=O)NR'R''). Carbamates also refer to urethane-type linkages found in polymers. They occur widely in pesticides, pharmaceuticals, and industrial materials.

In practice, carbamates have two broad applications. Many were developed as pesticides, including carbaryl (Sevin), aldicarb, methomyl, and carbofuran, used to control insects on crops and stored products. Carbamates also function as protecting groups in organic synthesis; the tert-butoxycarbonyl (BOC) group is a common N-protecting group for amines, installed by reactions with Boc reagents. Additionally, urethane linkages in polyurethanes arise from reactions involving carbamate formation, linking with diisocyanates and polyols to form versatile polymers.

Chemistry and properties of carbamates vary with substituents. They are generally hydrolyzable under acidic or basic conditions, yielding corresponding amines or alcohols and carbon dioxide or related fragments. As cholinesterase inhibitors, many carbamates act by reversible carbamoylation of the active site Serine in acetylcholinesterase, a mechanism behind their insecticidal activity and potential mammalian toxicity. Environmental and regulatory considerations apply, with several carbamate pesticides subject to restrictions or phaseouts due to toxicity to non-target species and persistence in ecosystems.

Synthesis routes include reactions of amines with chlorocarbonates or phosgene-derived reagents to form carbamate esters, and the use of Boc2O to install the Boc protecting group. In polymer chemistry, urethane formation from isocyanates and alcohols or polyols produces carbamate linkages central to polyurethane materials.