Product formation from the reaction of the NO3 radical with isoprene and rate constants for the reactions of methacrolein and methyl vinyl ketone with the NO3 radical

Kinetic and product studies of the reactions of NO3 with a series of unsaturated organic compounds

“…The rate constant of methacrolein + NO 3 has been measured mainly by the relative method (Kwok et al 1996, Chew et al 1998, Canosa-Mas et al 1999, only one study from Rudich et al (1996) applied an absolute method and observed an upper limit of <8×10 -15 cm 3 molecule -1 s -1 . The value of this work agrees well with the studies using the relative method and hence we recommend a weighted average of (3.3±0.9)×10 -15 cm 3 molecule -1 s -1 , which is in good agreement with IUPAC value (3.4±0.6)×10 -15 cm 3 molecule -1 s -1 at 298 K. The rate constant of methyl vinyl ketone reaction with NO 3 radical in this work is in the range of upper limit value of Rudich et al (1996), but lower than that of Canosa-Mas et al (1999) and Kwok et al (1996) who used relative method. Hence we recommend a preferred value as (1.3±0.6)×10 -16 cm 3 molecule -1 s -1 obtained in this work.…”

Theoretical and experimental study of peroxy and alkoxy radicals in the NO3-initiated oxidation of isoprene

“…A recent review by Wennberg et al 4 gives a good overview of the status quaestionis of isoprene oxidation by OH and NO 3 , based on the available literature on the NO 3 -initiated oxidation of isoprene up to now. [39][40][41][42][43][44][45][46][47][48] In this work, we investigate several aspects of the first stages of the NO 3 -initiated oxidation of isoprene, and of measurements of nitrated RO 2 radicals, as summarized in Fig. 1.…”

A product study of the isoprene+NO&lt;sub&gt;3&lt;/sub&gt; reaction

“…Not only is NO 3 an important isoprene sink but, because of the high yield, INs formed by NO 3 -initiated oxidation may represent a large fraction of the total IN source (Horowitz et al, 2007). Kwok et al (1996) studied the products of the NO 3 +isoprene reaction using API-MS and observed the formation of C 5 carbonyl nitrates, C 5 hydroxy nitrates, C 5 hydroperoxy nitrates and C 5 hydroxy carbonyls. They also observed methacrolein (CH 2 C(CH 3 )CHO or MACR) and methyl vinyl ketone (CH 3 C(O)CHCH 2 or MVK) formation and found each produced with a 3.5% yield.…”

“…This intermediate reacts with O 2 to produce a nitrooxy peroxy radical (step 2), which undergoes subsequent reactions to form a stable nitrate product (pathways 3a 1 , 3c 2 , 4a 1 ) or dissociates to give NO 2 and an oxidized hydrocarbon (pathways 4b or 5) (Skov et al, 1992;Berndt and Boge, 1997). Both theoretical (Suh et al, 2001) and experimental (Skov et al, 1992;Kwok et al, 1996;Berndt and Boge, 1997) studies of the kinetics of NO 3 + isoprene have shown that addition of NO 3 at the C 2 or C 3 positions is negligible and that addition of NO 3 at the C 1 position (shown) dominates over addition at the C 4 position (not shown). Estimates range from 75-85% C 1 addition with the balance C 4 addition (Skov et al, 1992;Berndt and Boge, 1997).…”

“…MVK and MACR are produced from reactions of the β-peroxy radicals. C 5 hydroxy carbonyls are thought to result from a cyclic hydrogen abstraction rearrangement of the δ-alkoxy radicals (pathway 5) (Kwok et al, 1996).…”