The formation of aliphatic carbon–nitrogen bonds
An aliphatic nitro compound, available through vapour-phase nitration, is heated with hydrochloric acid; the acid catalyzes the formation of the tautomer, an anionotropic shift via the addition and elimination of water and the reverse of hydroxamic acid formation. With the exception of a few methods involving free-radical reactions, the methods for forming bonds between nitrogen and aliphatic carbon fall into two categories. In the first, nucleophilic nitrogen reacts with electrophilic carbon and, in the second, electrophilic nitrogen reacts with nucelophilic carbon. A ternary nitrogen atom possesses an unshared pair of electrons and is therefore nucleophilic. The carbon centres to which electrophilic nitrogen bonds include both carbanions and neutral molecules such as enols which are particularly reactive towards electrophiles. Primary amines react with chloroform and alkali-metal hydroxides to give carbylamines. A carbonyl group attached to a group capable of departing with the covalent bonding-pair is susceptible to substitution by nitrogen nucleophiles.