Reaction of oxygen atoms, O(3P), with olefins in liquid nitrogen solution at 770K

Abstract

The reaction of ground-state oxygen atoms, 0(3P), with ethylene and ethylene-d, in liquid nitrogen solution at 77 "K has been studied. The major and perhaps the exclusive products are ethylene oxide and acetaldehyde. The ratio of acetaldehyde to ethylene oxide is 1.2 1 0.1 for ethylene and 0.91 + 0.09 for ethylene-d4. Much smaller amounts of formaldehyde and trace quantities of cyclopropane are also observed. The effect of the concentration of ethylene on the quantum yields of addition products was measured. A limiting quantum yield of oxygen atoms scavenged by ethylene to form the addition products was 0.12+0.01. The low quantum yield suggests an appreciable cage recombination of the ground-state oxygen atoms with the trace amounts of molecular oxygen present. The effect of the concentration of added oxygen on the product yields and the relative rate constant for the addition of 0(3P) to molecular oxygen and to ethylene were determined. The ratio ko+02/ko+c,H, is 6.0 i 1.0 and the relative rate constant for the addition of 0(3P) to ethylene and to ethylene-d,, ko+c,D4/ko+c,~,, is 2.0 i. 0.1. The type of products formed and the isotope effects observed are discussed in terms of the mechanism of addition of 0(3P) atoms to ethylene. La reaction des atomes d'oxygene I'Ctat fondamental, 0(3P) avec I'ethylene et ]'ethylene-d, en solution d'azote liquide a 77 "K a et6 CtudiCe. Les produits majeurs et peut-Ctre les seuls formts sont I'oxyde d'ethylene et I'adtaldLhyde. Le rapport d'acetaldehyde versus l'oxyde d'ethylene est 1.2 + 0.1 pour I'ethylene et 0.91 + 0.09 pour I'ethylene-d,. Des quantites beaucoup plus faibles de formaldehyde ainsi que des traces de cyclopropane sont aussi obtenues. L'effet de la concentration d'ethylene sur le rendement quantique des produits d'addition a Cte mesure. Un rendement quantique limite d'atomes d'oxygkne trappes par I'tthyl6ne pour former les produits d'addition a ete de 0.12 + 0.01. Le petit rendement quantique suggere une recombinaison appreciable en cage des atomes d'oxygene dans I'etat fondamental avec des quantitis minimes (traces) d'oxygene molCculaire present. L'effet de la concentration d'oxygene ajoute sur le rendement en produits et la constante de vitesse relative a I'addition de 0(3P

Electrophilic Oxidant Produced in the Photodeoxygenation of 1,2-Benzodiphenylene Sulfoxide

“…Gas-phase mercury triplet photosensitized decomposition of N 2 O indicates formation of O( 3 P) based on energetics; , however, a common method for spectroscopic detection of O( 3 P) requires monitoring its vacuum UV laser-induced fluorescence (LIF) signal at ∼130 nm . The disadvantage of current methods that generate O( 1 D) or O( 3 P) in solution, include (1) harsh photolysis conditions (e.g., [ 60 Co] γ-ray irradiation of liquid water or alkaline H 2 O 2 solutions, 185 nm photolyses of N 2 O), (2) the presence of other reactive intermediates (e.g., oxoanions and oxoacids, photodecomposition products of NO 3 -13 ), or (3) the need for high-pressure (e.g., SF 6 ) 14 or low temperature (N 2 ) solvents. We now report a much cleaner oxidation method.…”

Oxidation of Propylene with Oxygen and Air in a Barrier Discharge in the Presence of Octane

“…An analysis of the literature data [16,17] dealing with the reactions of O( 3 P) with olefin molecules shows that an O( 3 P) atom gets attached to a carbon atom of the double bond. The resulting adduct (alkenoxy radical) is rearranged to form a final product by ring closure (formation of an epoxide) or by migration of a hydrogen atom or an alkyl group from the carbon atom, which is conjugated with O( 3 P), to another carbon atom of the initial double bond (formation of carbonyl compounds).…”

“…According to Hirokami and Cvetanovic [16] the main products of the reaction of propylene with an O( 3 P) atom are propylene oxide, propanal, and acetone. The data on the reaction mechanism between the atomic oxygen O( 1 D) and propylene are even more scarce than those on the reaction with an O( 3 P) atom.…”

“…The condensate formed flew down the reactor walls as a film, thus providing an effective transport of products from the discharge region. The resulting condensate with the dissolved oxidation products drained down the walls of the reactor as a film into the receiver-flask (16). The receiver flask was cooled to -20°C with a mixture of sodium chloride and ice (17).…”

Observation of Light-Induced Reactions of Olefin–Ozone Complexes in Cryogenic Matrices Using Fourier-Transform Infrared Spectroscopy

“…It is known that the reaction of C 2 H 4 and an oxygen atom ( 3 P) in the gas phase at room temperature produces mainly CH 3 CHO and fragmented products due to the high excess energy of the C 2 H 4 O adduct [43]. Conversely, in liquid N 2 , the addition reaction leads to the simultaneous formation of c-C 2 H 4 O and CH 3 CHO with a comparable branching ratio, owing to the rapid energy release of the adduct into the cold media [44]. The absence of CH 3 CHO in the photoproducts in the Ar matrix suggests that the photoreaction of the C 2 H 4 + O 3 system is not stepwise as follows:…”