Gauging the Significance of Atomic Oxygen [O(³P)] in Sulfoxide Photochemistry. A Method for Hydrocarbon Oxidation

Abstract

A liquid-phase photolysis of 1,2-benzodiphenylene sulfoxide, 1, and dibenzothiophene sulfoxide, 2, was used to generate atomic oxygen [O(3P)] or an equivalent active oxygen species. The reaction for sulfoxide photodeoxygenation was similar to a microwave discharge method for generating O(3P) atoms in the condensed phase (Zadok, E.; Rubinraut, S.; Mazur, Y. J. Org. Chem. 1987, 52, 385-90). Sulfoxide photodeoxygenation is a potentially clean method for O(3P) production compared to the microwave discharge method. With Argon purging of the sulfoxide sample before photolysis, the method can preclude a secondary oxidation process involving molecular oxygen. Our study focused on the results of oxidation products in the reaction of styrene, 3, and on the dependence of substrates that provided an opportunity to vary the electronic and steric effects. The sulfoxide photochemistry is rationalized with the primary formation of O(3P) in which a charge-transfer interaction between O(3P) and substrate precedes oxidation. Functionalization of hydrocarbons takes place under mild photolysis conditions of 1 and 2, which leads to an interesting possibility for the synthetic use of atomic oxygen, O(3P). Alkanes give principally alcohols. Alkenes give principally epoxides and ketones. For comparison, hydroxyl radicals are more reactive and less selective toward hydrocarbons compared to O(3P) atoms. On the other hand, O(3P) atoms balance reactivity and selectivity and involve the oxidation of inert alkanes typically inaccessible to peracid, dioxirane, ozone, and singlet molecular oxygen chemistry. The findings from this study may be useful to those interested in generating high-value oxygenated compounds from readily available petroleum components.

Relationship between the bubble temperature and main oxidant created inside an air bubble under ultrasound

“…The methods to detect oxygen atom in liquid have been reported in the literatures. [39][40][41][42][43][44][45][46] For example, a nonvolatile solute having a branched carbon chain such as ͑CH 3 ͒ 2 CHCH 2 COO − can be used to detect oxygen atoms in liquid: ͑CH 3 ͒ 2 CHCH 2 COO − +O͑3P͒ → ͑CH 3 ͒ 2 C͑OH͒CH 2 COO − , where O͑3P͒ is an oxygen atom in its triplet ground state. It should be noted that only nonvolatile solute can be used to detect oxygen atoms in liquid phase because volatile solutes enter bubbles and may react with oxygen atoms in the gas phase inside bubbles.…”

S,C-Sulfonium Ylides from Thiophenes: Potential Carbene Precursors

“…Such 1,2-shifts have been demonstrated repeatedly for nitrogenous carbene precursors that are subject to 1,2 hydrogen shifts or carbon shifts to relieve ring strain. [4][5][6][7][8][9][10] We 11-13 and others [14][15][16][17][18] have shown in previous work that photolysis of dibenzothiophene-S-oxide and its derivatives leads to chemistry that appears to derive from S-O cleavage and formation of atomic oxygen. Although direct evidence for this mechanism in the form of spectroscopic detection of O( 3 P) is lacking, we have recently shown through time-resolved IR experiments that benzoyl nitrene is formed on photolysis of N-benzoyl dibenzothiophene sulfilimine.…”

Photochemical and Electrochemical Oxygenation of Thiophenes, Benzo[b]Thiophenes and Dibenzothiophenes; Photochemical and Electrochemical Behaviour of Their Oxygenated Intermediates and Products

“…50 If trace amounts of molecular oxygen are present in the photoreaction vessel prior to irradiation, benzaldehyde 44 and acetophenone 43 can also be obtained as products. 50 If trace amounts of molecular oxygen are present in the photoreaction vessel prior to irradiation, benzaldehyde 44 and acetophenone 43 can also be obtained as products.…”