An MNDO study of the reaction of methanol with fulminic acid and acetonitrile oxide

The reaction pathway of fulminic acid (HCNO) and acetonitrile oxide (CH₃CNO) with methanol as a nucleophile (RCNO + CH₃OH → RC(OCH₃)?NOH) and the formation of H-bonded complex with methanol have been studied using the MNDO method. MNDO-SCF calculations were performed with complete geometry optimization using the Davidon–Fletcher–Powell method. The reaction pathways were studied by varying all the bond lengths, the bond angles and the twist angles, using the distance C₃? O₂(R) between the carbon of the 1,3-dipoles and the oxygen of the methanol molecule as the reaction coordinate. The reaction is exothermic and proceeds in two steps. The first step is the formation of a five-centered hydrogen-bonded complex (INT ) and is the rate-determining step of the reaction. The second step involves the rearrangement of the H-bonded complex to the product, and this step requires a very small amount of activation energy. Thus, there is an intermediate on the reaction pathway, and therefore, the reaction is stepwise. Acetonitrile oxide is less reactive (activation energy 34.59 kcal/mol) relative to fulminic acid (activation energy 28.91 kcal/mol).