| Abstract: | Rate constants have been measured at 296 ± 2 K for the gas‐phase reactions of camphor with OH radicals, NO3 radicals, and O3. Using relative rate methods, the rate constants for the OH radical and NO3 radical reactions were (4.6 ± 1.2) × 10?12 cm3 molecule?1 s?1 and <3 × 10?16 cm3 molecule?1 s?1, respectively, where the indicated error in the OH radical reaction rate constant includes the estimated overall uncertainty in the rate constant for the reference compound. An upper limit to the rate constant for the O3 reaction of <7 × 10?20 cm3 molecule?1 s?1 was also determined. The dominant tropospheric loss process for camphor is calculated to be by reaction with the OH radical. Acetone was identified and quantified as a product of the OH radical reaction by gas chromatography, with a formation yield of 0.29 ± 0.04. In situ atmospheric pressure ionization tandem mass spectrometry (API‐MS) analyses indicated the formation of additional products of molecular weight 166 (dicarbonyl), 182 (hydroxydicarbonyl), 186, 187, 213 (carbonyl‐nitrate), 229 (hydroxycarbonyl‐nitrate), and 243. A reaction mechanism leading to the formation of acetone is presented, as are pathways for the formation of several of the additional products observed by API‐MS. © 2000 John Wiley and Sons, Inc. Int J Chem Kinet 33: 56–63, 2001 |
