An
addition reaction, in
organic chemistry, is in its simplest terms an
organic reaction where two or more molecules combine to form a larger one (the
adduct). Addition reactions are limited to chemical compounds that have multiple bonds, such as molecules with carbon-carbon
double bonds (
alkenes), or with
triple bonds (
alkynes). Molecules containing carbon—
hetero double bonds like
carbonyl (C=O) groups, or
imine (C=N) groups, can undergo addition as they too have double bond character.