Atmospheric reactivity of HCCCH₂OH (2-propyn-1-ol) toward OH radicals: experimental determination and theoretical comparison with its alkyne analogue

Abstract

The rate coefficient for the reaction of propargyl alcohol (2-propyn-1-ol, 2P1OL) with OH radicals has been determined using gas chromatography with a flame ionization detector (GC/FID) at 298 K and atmospheric pressure. The experimental value obtained by the relative method using methyl methacrylate and butyl acrylate as references was (2.05 AE 0.30) Â 10 À11 cm 3 per molecule per s. The present value was compared with previous determinations and a theoretical study of the reaction was performed in order to explain the differences in reactivity of the alcohol with that of the corresponding alkyne (propyne, P). A full discussion of the addition and abstraction mechanisms was developed for 2P1OL at the density functional and ab initio composite model levels. It was found that addition is much faster than abstraction for propyne but occurs at approximately the same rate for 2P1OL. In this last case, however, abstraction of hydrogen from the C1 carbon leads to a complex which can react further to yield addition products. Thermodynamic and kinetic data calculated for these reactions suggest that the products would be the 1,2-and 1,3-propanediol radicals. These products would react further with O 2 , in the case where it is present in the reaction mixture.