Rate constants for the reactions of OH radicals with alkyl substituted olefins

Relative rate constants for the reactions of hydroxyl radicals with a series of alkyl substituted olefins were measured by competitive reactions between pairs of olefins at 298 ± 2 K and 1 atmospheric pressure. Hydroxyl radicals were produced by the photolysis of H2O2 with 254‐nm irradiation. The obtained rate constants were (× 10−11 cm3 molecule−1 s−1): 2.53 ± 0.06, propylene; 5.49 ± 0.17, cis‐2‐butene; 5.47 ± 0.1, isobutene; 6.46 ± 0.13, 2‐methyl‐1‐butene; 6.37 ± 0.16, cis‐2‐pentene; 6.23 ± 0.1, 2‐methyl‐1‐pentene; 8.76 ± 0.14, 2‐methyl‐2‐pentene; 6.24 ± 0.08, trans‐4‐methyl‐2‐pentene; 10.3 ± 0.1, 2,3‐dimethyl‐2‐butene; 9.94 ± 0.1, 2,3‐dimethyl‐2‐pentene; 5.59 ± 0.07, trans‐4,4‐dimethyl‐2‐pentene. A trend in alkyl substituent effect on the rate constant was found, which is useful to predict kOH on the basis of the number of alkyl substituents on the double bond.