Kinetics and Products of the OH Radical-Initiated Reaction of 1,4-Butanediol and Rate Constants for the Reactions of OH Radicals with 4-Hydroxybutanal and 3-Hydroxypropanal

Rate constants for the gas-phase reactions of the OH radical with 1,4-butanediol, 4-hydroxybutanal, and 3-hydroxypropanal were measured at 298 +/- 2 K and atmospheric pressure using a relative rate technique and with 4-hydroxybutanal and 3-hydroxypropanal being formed in situ from the OH + 1,4-butanediol reaction, and were (in units of 10(-11) cm(3) molecule(-1) s(-1)) 3.67 +/- 0.31, 3.0(-1.0)(+1.5), and 3.5(-1.0)(+1.3), respectively, with the latter being a lower limit because of the possibility of second-generation formation of 3-hydroxypropanal from OH + 4-hydroxybutanal. The measured formation yields of 4-hydroxybutanal and 3-hydroxyproparial from the OH + 1,4-butanediol reaction in the presence of NO were 58 +/- 19% and 55 +/- 12%, respectively. In addition to the formation of 4-hydroxybutanal and 3-hydroxypropanal, gas chromatography-mass spectrometric analyses of reacted OH + 1,4-butanediol reactions showed formation of glycolaldehyde [HOCH(2)CHO], malonaldehyde [HC(O)CH(2)CHO], and 1,4-butanedial [HC(O)CH(2)CH(2)CHO]. Glycolaldehyde, malonaldehyde, and 1,4-butanedial are expected products of the reaction of OH radicals with 4-hydroxybutanal, and glycolaldehyde and malonaldehyde are expected products of the reaction of OH radicals with 3-hydroxypropanal. Reaction mechanisms are presented and discussed.