Reactivity of selected volatile organic compounds (VOCs) toward the sulfate radical (SO4-)

Rate constants for a series of alcohols, ethers, and esters toward the sulfate radical (SO4-) have been directly determined using a laser photolysis set-up in which the radical was produced by the photodissociation of peroxodisulfate anions. The sulfate radical concentration was monitored by following its optical absorption by means of time resolved spectroscopy techniques. At room temperature the following rate constants were derived: methanol ((1.6 +/- 0.2) x 10(7) M-1 s(-1)); ethanol ((7.8 +/- 1.2) x 10(7) M-1 s(-1)); tert-butanol ((8.9 +/- 0.3) x 10(5) M-1 s(-1)); diethyl ether ((1.8 +/- 0.1) x 10(8) M-1 s(-1)); MTBE ((3.13 +/- 0.02) x 10(7) M-1 s(-1)); tetrahydrofuran (THF) ((2.3 +/- 0.2) x 10(8) M-1 s(-1)); hydrated formaldehyde ((1.4 +/- 0.2) x 10(7) M-1 s(-1)); hydrated glyoxal ((2.4 +/- 0.2) x 10(7) M-1 s(-1)); dimethyl malonate (CH3OC(O)CH2C(O)OCH3) ((1.28 +/- 0.02) x 10(6) M-1 s(-1)); and dimethyl succinate (CH3OC(O)CH2CH2C(O)OCH3) ((1.37 +/- 0.08) x 10(6) M-1 s(-1)) where the errors represent 2 sigma. For the two latter species, we also measured the temperature dependence of the corresponding rate constants. A correlation of these kinetics with the bond dissociation energy is also presented and discussed. (C) 2001 John Wiley & Sons, Inc.