Experimental product study of the OH-initiated oxidation of m-xylene

We performed laboratory studies to investigate the OH-initiated oxidation of m-xylene using a fast flow reactor coupled to ion drift-chemical ionization mass spectrometry (ID-CIMS). Seven products consisting of ring-retaining and ring-opening components have been identified and quantified. Three products, methylglyoxal, 4-oxo-2-pentenal and 2-methyl-4-oxo-2-butenal, and dimethylphenols exhibited a dependence of the formation yields on the O2 and NO concentration. We reported for the first time the yields (%) of three other products, 2-methyl-4-oxo-2-penetal (4.89 ± 0.52), diunsaturated dicarbonyls (2-methyl-6-oxo-2,4-heptadienal and 4-methyl-6-oxo-2,4-heptadienal, 7.82 ± 1.0), and epoxy carbonyls (2,4-dimethyl-2,3-epoxy-6-oxo-4-hexenal, 2,6-dimethyl-2,3-epoxy-6-oxo-4-hexenal, and 3,5-dimethyl-2-hydroxyl-3,4-epoxy-5-hexenal, 2.18 ± 0.20). m-Tolualdehyde, with a yield of 6.42 ± 0.89, is consistent with previous studies. The yield of methylglyoxal (15.1 ± 4.2) is consistent with its co-products, but lower than the literature values. The dependence of product distributions on O2 and NO concentration was discussed. The mechanism leading to the formation of the products was proposed.