THE HYDROXYL RADICAL REACTION-RATE CONSTANT AND ATMOSPHERIC TRANSFORMATION PRODUCTS OF 2-BUTANOL AND 2-PENTANOL

The relative rate technique has been used to measure the hydroxyl radi cal (OH) reaction rate constant of +2-butanol (2BU, CH3CH2CH(OH)CH3) a nd 2-pentanol (2PE, CH3CH2CH2CH(OH)CH3). 2BU and 2PE react with OH yie lding bimolecular rate constants of (8.1 +/- 2.0) X 10(-12) cm(3)molec ule(-1)s(-1) and (11.9 +/- 3.0) X 10-12 cm(3)molecule(-1)s(-1), respec tively, at 297 +/- 3 K and 1 atmosphere total pressure. Both 2BU and 2 PE OH rate constants reported here are in agreement with previously re ported values [1-4]. In order to more clearly define these alcohols' a tmospheric reaction mechanisms, an investigation into the OH + alcohol reaction products was also conducted. The OH + 2BU reaction products and yields observed were: methyl ethyl ketone (MEK, (60 +/- 2)%, CH3CH 2C(=O)CH3) and acetaldehyde ((29 +/- 4)% HC(=O)CH3). The OH + 2PE reac tion products and yields observed were: 2-pentanone (2PO, (41 +/- 4)%, CH3C(=O)CH2CH2CH3), propionaldehyde ((14 +/- 2)% HC(= O)CH2CH3), and acetaldehyde ((40 +/- 4)%, HC(=O)CH3). The alcohols' reaction mechanis ms are discussed in light of current understanding of oxygenated hydro carbon atmospheric chemistry. Labeled (O-18) 2BU/OH reactions were con ducted to investigate 2BU's atmospheric transformation mechanism detai ls. The findings reported here can be related to other structurally si milar alcohols and may impact regulatory tools such as ground level oz one-forming potential calculations (incremental reactivity) Isl. (C) 1 998 John Wiley C Sons, Inc.