Amines (US: or , UK: , or ) are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. (These may respectively be called alkylamines and arylamines; amines in which both types of substituent are attached to one nitrogen atom may be called alkylarylamines.) Important amines include amino acids, biogenic amines, trimethylamine, and aniline; see for a list of amines. Inorganic derivatives of ammonia are also called amines, such as chloramine (NClH₂); see .