STUDY OF THE OH-INITIATED DEGRADATION OF THE AROMATIC PHOTOOXIDATION PRODUCT 3,4-DIHYDROXY-3-HEXENE 2,5-DIONE

Using long-path FTIR absorption spectroscopy, the kinetics and product s of the reaction of OH radicals with the enediol form of acetylformoi n, 3,4-dihydroxy-3-hexene-2,5-dione, an important aromatic photooxidat ion product, have been investigated in a 1080-L reaction chamber. A ra te coefficient of (2.7 +/- 0.7) x 10(-10) cm(3) molecule(-1) s(-1) has been obtained for the reaction at 296 +/- 2 K in 1000 mbar of synthet ic air. Pyruvic acid and CO have been identified as minor reaction pro ducts. The experimental evidence supports that the major product is pr obably a hydrated vicinal polyketone, 3,3-dihydroxyhexane-2,4,5-trione . The results also imply that polyketones will be important products i n the photooxidation of alkylated benzenes and that they could account for 25-30% of the missing carbon in aromatic oxidation systems.