Reactions of Ozone with Unsaturated Organic Compounds

Abstract

The basis 3df2df in Table 1 again contains one set of $functions on all heavy atoms. Second row atoms carry three sets of &functions but first row atoms only two. When this basis set is used instead of 6-31 lG(2dJp) the atomization energies of C10, OC10, and ClOO are all in acceptable agreement with experiment.The basis 3df2df has been applied to two further test molecules and to the C103-isomers. For all species in Table 1 but ClOCl the deviation is less than 5 kcalfmol.The G1 calculations on C103-isomers were started with geometry optimizations on the HF/6-31G*-and MP2f6-31G*-levels of theory. All three supposed isomers, C1000, OC100, and sym-C103 were found as minima [9] on the potential energy hypersurface. The GI total energy calculations using the basis set described above gave heats of formation of 41, 58, and 48 kcalfmol, respectively.From these ab initio calculations it appears that ClOOO might be considered as an intermediate in reaction (1). Since it is a real minimum on the potential energy hypersurface, there must exist a barrier for the exothermic dissociation of ground state ClOOO into C10 and 02.The work was supported in part by the BMFT, Bonn, withinThe authors acknowledge access to the facilities of the Hochstproject 0744120 0.leistungsrechenzentrum Julich. References Howard SidebottomUniversity College Dublin, Ireland Chemical Kinetics f Elementary Reactions f RadicalsRate constants for the gas-phase reactions of ozone with a series of alkenes have been determined using a conventional static system. Ozone loss was monitored in excess of the hydrocarbon and rate data measured at 1 atmosphere total pressure over the temperature range 240-324 K. The Arrhenius parameters obtained are discussed in terms of structure-reactivity relationships. Product studies have been carried out for the reaction of O3 with the conjugated dienes, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene) and 2,3-dimethyl-1,3-butadiene in air. The results provide information on the decomposition pathways for the primary ozonides and the relative importance of ozone addition to the two doublebonds in isoprene.cant reactivity towards ozone as well as towards hydroxyl and nitrate radicals. Numerous potentially important roles of the ozone-alkene reaction have been recognized since these reactions can provide mutual sinks for both ozone and alkenes and concomitantly serve as sources of partially oxidised compounds e. g. CO, aldehydes, ketones and organic

Environmental effects of large igneous province magmatism: a Siberian perspective

“…O 3 + C 3 H 6 . The rate constant of this reaction is well established over the temperature range 185 to 360 K. The present recommendation is based largely on the data of Herron and Huie [576], in the temperature range 235-362 K. (Note that a typographical error in Table 2 of that paper improperly lists the lowest temperature as 250 K, rather than the correct value, 235 K.) The recommended Arrhenius expression agrees within 25% with the low temperature (185-195 K) data of DeMore [366], and is consistent with, but slightly higher (about 10%) than Treacy et al [1320] and slightly lower (about 40%) than the data of Adeniji et al [10] in the temperature range 260-294 K. Room temperature measurements of Cox and Penkett [328], Stedman et al [1234], Japar et al [650,651], and Atkinson et al [44] and Neeb and Moorgat [948] are in good agreement (10% or better) with the recommendation. (Table: 06-2, Note: 06-2) Back to Table D10.…”

Secondary organic aerosol formation from the photooxidation of isoprene, 1,3-butadiene, and 2,3-dimethyl-1,3-butadiene under high NO<sub>x</sub> conditions

“…The O 3 level when the lights were turend off was about 300 ppb. This O 3 concentration was confirmed to be high enough to explain the loss rate of m/z 71 in the dark; the loss rate of methyl vinyl ketone was 3.2 × 10 −5 s −1 ; the loss rate of methacrolein was 8.2 × 10 −6 s −1 ; where the rate constants measured by Treacy et al (1992) were used. When the lights are turned off, SOA particles had already been produced (Fig.…”

On the use of CO as scavenger for OH radicals in the ozonolysis of simple alkenes and isoprene

“…The significance of (7) depends on the system studied. For TME, CB, and TB, for which k 1 varies in the range 1,24 ϫ to [3,4], the Thus, HO 2 formation and its reaction with O 3 do not appreciably affect the total OH yields and, therefore, the increase in CO 2 in the scavenging experiments with CO may be predominantly attributed to reaction (3) and equated to the formation of primary OH in the ozonolysis. A different situation is experienced in the ozonolysis of ET.…”