Atmospheric Chemistry of Trimethoxymethane, (CH3O)3CH; Laboratory Studies

A pulse radiolysis technique was used to measure the UV absorption spectra of (CH 3 O) 2 CHOCH 2 (·) and (CH 3 O) 2 CHOCH 2 O 2 (·) radicals derived from trimethoxymethane over the range 220−320 nm, σ 250 nm (CH 3 O) 2 CHOCH 2 (·) = (2.8 ± 0.4) × 10 -18 and σ 250 nm (CH 3 O) 2 CHOCH 2 O 2 (·) = (3.5 ± 0.4) × 10 -18 cm 2 molecule -1 . The self-reaction rate constants for (CH 3 O) 2 CHOCH 2 (·) and (CH 3 O) 2 CHOCH 2 O 2 (·) radicals, defined as −d[(CH 3 O) 2 CHOCH 2 (·)]/d t = 2 k 5 [(CH 3 O) 2 CHOCH 2 (·)] 2 and −d[(CH 3 O) 2 CHOCH 2 O 2 (·)]/d t = 2 k 6 obs [(CH 3 O) 2 CHOCH 2 O 2 (·)] 2 were k 5 = (3.5 ± 0.5) × 10 -11 and k 6 obs = (1.3 ± 0.2) × 10 -11 cm 3 molecule -1 s -1 . Rate constants for reactions of (CH 3 O) 2 CHOCH 2 O 2 (·) radicals with NO and NO 2 were k 7 = (9.0 ± 1.2) × 10 -12 and k 8 = (1.0 ± 0.2) × 10 -11 cm 3 molecule -1 s -1, respectively. Rate constants for the reaction of OH radicals and F atoms with trimethoxymethane and the reaction of (CH 3 O) 2 CHOCH 2 (·) radicals with O 2 were k 1 = (6.0 ± 0.5) × 10 -12, k 3 = (3.0 ± 0.7) × 10 -10, and k 2 = (9.2 ± 1.5) × 10 -12 cm 3 molecule -1 s -1, respectively. Relative rate techniques were used to measure k (Cl + trimethoxymethane) = (1.5 ± 0.2) × 10 -10 cm 3 molecule -1 s -1 . OH-radical-initiated oxidation of trimethoxymethane in air gives dimethyl carbonate in a molar yield of 81 ± 10%. These results are discussed with respect to the atmospheric chemistry of automotive fuel additives.