Methylglyoxal, atmosphere

These compounds, exemplified by acrolein, crotonaldehyde, and methyl vinyl ketone, are known to react with ozone and with OH radicals. Photolysis and N03 radical reaction are of minor importance. Under atmospheric conditions the 03 reactions are also of minor significance (Atkinson and Carter, 1984), leaving the OH radical reaction as the major loss process. For the aldehydes, OH radical reaction can proceed via two reaction pathways OH radical addition to the double bond and H-atom abstraction from the -CHO group (Atkinson, 1989). For crotonaldehyde, for example, the OH reaction mechanism is given in Fig. 3. As can be noted from Fig. 3, these a,/3-unsaturated aldehydes are expected to ultimately give rise to a-dicarbonyls such as glyoxal and methylglyoxal. For the a,/3-unsaturated ketones such as methyl vinyl ketone, the major... 

Barsanti, K. C., and Pankow, J. F. (2005) Thermodynamics of the formation of atmospheric organic particulate matter by accretion reactions—2. Dialdehydes, methylglyoxal, and diketones, Atmos. Environ. 39, 6597-6607. 

Mechanisms for the Atmospheric Oxidation of the Aldehydes 595 IV-D-3. Methylglyoxal [CH3C(0)CH0]... 

Products of the atmospheric oxidation of this species have not been determined, but high yields of acetone and methylglyoxal are anticipated from the OH-initiated process. 

The unsaturated 1,4-dicarbonyl compounds, e.g., 3-hexene-2,5-dione [CH3C(0)CH=CHC(0)CH3], are formed in significant yield from the oxidation of aromatic compounds. Their atmospheric behavior is summarized below. Butenedial, which is a co-product of methylglyoxal in the oxidation of toluene, is discussed with other unsaturated 1,4-dials in section lV-D-4. 

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