Linear‐reactor‐infrared‐matrix and microwave spectroscopy of the cis‐2‐butene gas‐phase ozonolysis

Abstract

SummaryInvestigation of the formation of complex products in the gas-phase ozonolysis of cis-2-butene by linear-reactor-infrared-matrix and linear-reactor-microwave spectroscopy is reported. The following species have been unequivocally detected: secondary 2-butene ozonide, acetic acid, peracetic acid, glycolaldehyde, dimethyl ketene, the simple and mixed anhydrides of formic and acetic acid, 2,3-epoxybutane and 2-butanone, besides polyatomic products already known. In contrast, the primary ozonide has been detectable neither by LR.-MW. nor by LR.-IR. Observation of both stereoisomeric epoxides and kinetic modelling are used to support the intermediate formation of the O'Neal-Blumstein radical CH3CH (02)CH (0)CH3 and the existence of a reaction channel in which the two carbon atoms of the C , C double bond of the olefin remain connected. As the dominant reaction path a mechanism with a Criegee type split into methyldioxirane (ethylidene peroxide) and acetaldehyde is considered and subsequently proposed to explain formation of many complex products by either unimolecular or bimolecular processes of the peroxide. For the reactions considered, thermochemical estimates of reaction enthalpies and activation data are included. Kinetic modelling for a partial reaction mechanism involving at least two different paths of decay of the O'Neal-Blumstein biradical into Criegee-type intermediates and the 2,3-epoxybutanes is discussed.

Infrared Matrix Isolation and Theoretical Study of the Initial Intermediates in the Reaction of Ozone with cis-2-Butene

“…Heicklen et al 31 and Kuhne et al 30 both have reported two infrared absorptions near 715 and 1062 cm -1 in their earlier studies. Heicklen et al tentatively assigned these two bands, along with several other bands, to the primary ozonide of cis-2-butene, cis-dimethyl-1,2,3-trioxolone.…”

Gas-Phase Ozonolysis of Alkenes. Recent Advances in Mechanistic Investigations

“…Beyond C 2 H 4 , no clear-cut mechanistic interpretation is available for the experimental ozonolysis data, as will be shown for the case of 2-butene isomers. − The ozonolysis of 2-butenes produces CH 3 CHO and CH 3 CHOO*; 20−40% of the latter is considered to stabilize the CH 3 CHOO intermediate in the gas phase under 1 atm at room temperature. In a matrix-isolation FTIR spectroscopic study of 2-C 4 H 8 ozonolysis, Horie and Moortgat 33,34 determined quantitatively the reaction products which were attributable to the decomposition of the excited CH 3 CHOO* and noted that the carbon balance obtained by summing up the identified products was ∼60%.…”

Kinetics and mechanisms of the gas-phase reactions of ozone with organic compounds under atmospheric conditions

“…A number of other product studies using gas chromatography or other analytical techniques have been carried out (see, for example, ref 46,[58][59][60][61][62][63][64], but since these studies have not provided information as definitive as those described above and in the following sections, these are not discussed further in this article.…”