An unusual case of carbon-nitrogen bond formation. Reactivity of a C-nitroso group toward acyl chlorides

Acyl chlorides react with nitrosobenzene in 99.9% acetonitrile and in the p resence of catalytic amounts of HCl giving the corresponding N-p-chlorophen ylhydroxamic acids. The spectroscopic and kinetic evidence obtained indicat es that the reaction is initiated by the formation of an N-chlorohydroxylam ine intermediate from nitrosobenzene and hydrochloride in the first, slow s tep of the process. The nucleophilic N-chlorohydroxylamine intermediate rea cts with acyl chloride (or possibly an acyl cation-chloride ion pair) to gi ve the addition acylnitroso intermediate which undergoes to nucleophilic at tack by chloride ion at the para position of the phenyl moiety and, after p roton transfer from carbon, the corresponding N-p-chlorophenylhydroxamic ac id is formed. (C) 2001 Elsevier Science Ltd. All rights reserved.