Reactions of acetic acid with hydroxylamine

The reaction of neutral hydroxylamine with acetic acid, despite being clearly exothermic, involves a very large energy barrier. The reaction of ionized hydroxylamine with acetic acid is also clearly exothermic, but again a significant energy barrier is found (around 24 kcal/mol at the CCSD(T) level).

The reaction of the most stable protonated isomer of hydroxylamine, NH_3_OH^+^, with acetic acid also involves a high barrier (more than 27 kcal/mol at the CCSD(T) level). Only the higher energy isomer, NH_2_OH^+^_2_, leads to a sensibly lower energy barrier (about 2.3 kcal/mol at the CCSD(T) level). Nevertheless, an estimate of the reaction coefficient at low temperatures such as those reigning in the interstellar medium gives very low values.