Difference in the reactions of N-methylhydroxylamine and N-phenylhydroxylamine with nitrosobenzene

Article abstract of DOI:10.1246/bcsj.71.2381

The reaction of nitrosobenzene with N-methylhydroxylamine was studied. The pH-rate profile exhibits a negative break at between pH 0.5 and 3.0, which is considered to be caused by a change in the rate-determining step of the reaction from an attack of the amine on nitrosobenzene at low pH, to the dehydration of an addition intermediate previously formed between the reagents at higher pH. This behavior is different from that of the reaction between N-phenylhydroxylamine and nitrosobenzene where, over the entire pH range, the only rate-determining step is dehydration of the addition intermediate. This fact confirms the special behavior of phenylhydroxylamine as a nucleophile, as was observed in its reactions with aromatic aldehydes.