The reaction of the hydroxyl radical with acetylene

Abstract

Abstract The reaction of OH with acetylene was studied in a discharge flow system at room temperature. OH was generated by the reaction of atomic hydrogen with NO 2 and was monitored throughout the reaction using ESR spectroscopy. Mass‐spectrometric analysis of the reaction products yielded the following results: (1) less than 3 molecules of OH were consumed, and less than 2 molecules of H 2 O were formed for every molecule of acetylene that reacted; (2) CO was identified as the major carbon‐containing product; (3) NO, formed in the generation of OH, reacted with a reaction intermediate to give among other products N 2 O. These observations placed severe limitations on the choice of a reaction mechanism. A mechanism containing the reaction OH + C 2 H 2 → HC 2 O + H 2 better accounted for the experimental results than one involving the abstraction reaction OH + C 2 H 2 → C 2 H + H 2 O. The rate constant for the initial reaction was measured as 1.9 ± 0.6 × 10 −13 cm 3 molecule −1 sec −1 .