Singlet-oxygen generation in the catalytic reaction of dioxiranes with nucleophilic anions

Abstract

Nucleophilic anions such as Cl(-), I(-), Br(-), t-BuO(-), O(2)(-) and OH(-) efficiently catalyze the decomposition of dimethyldioxirane (DMD) and methyl(trifluoromethyl)dioxirane (TFD). Singlet oxygen ((1)O(2)) is formed in these catalytic reactions, as demonstrated by the characteristic infrared chemiluminescence (IR-CL) at 1268 nm. The yield of (1)O(2) generation, measured by the IR-CL method, lies in the range between 2 and 98%, which depends on the particular anion employed. For the bromide ion, the catalytic decomposition of the dioxirane is in competition with the oxidation of Br(-) to elemental bromine.

Mechanism of singlet oxygen generation during catalytic decomposition of methyl(trifluoromethyl)dioxirane by chloride ions

“…Actually, there is a general tendency for a decrease in the yield of 1 O 2 in the series of anions used for the decomposition of dioxiranes (Cl --Br --I --Me 3 CO --HO -), 8,9 which is attributed to the fact that the probabili ty of the redox pathway of this reaction increases in this series. 31 According to our data, the effective catalyst pro viding a high yield of singlet oxygen should have high ionization potentials (which is equivalent to the high ЕА of the reduced state) for both catalytic forms.…”

“…It is interesting to compare the mechanism proposed in the present study with the earlier mechanistic descrip tion of the pathways of this process 8, 9 shown in Scheme 1. The important difference between the two mechanisms is the nature of the oxidized form of the catalyst and, as a consequence, the structure of the precursor of singlet oxygen (intermediate А in Scheme 1).…”

“…The located set of stationary points on the potential energy surface for the reaction under consideration suggests the following scheme of transformations, which explains the experimental ob servations of the catalytic decomposition of TFD accom panied by the efficient generation of singlet oxygen. 9 In a solution in TFA, the catalyst exists mainly as complex 2. (1) Hereinafter, the ion dipole pairs are enclosed in square brackets.…”

“…In the case of chloride ions, the yield of 1 O 2 is 97 and 69% for DMD and TFD, respectively. 9 Taking into account the high yields of singlet oxygen and the important role of dioxiranes in organic synthe sis 1-3 and chemiluminescence of oxidation reactions, 2,10-12 detailed data on the mechanism of the reactions of di oxiranes with anions are of considerable interest. These data can provide deeper insight into the generation of ex Scheme 1 X = Cl, Br, l, Me 3 CO, OH cited states in reactions of peroxides, can help in under standing the factors having an effect on the stability of dioxiranes in solutions, and can be useful in the examina tion of the possibility of the practical application of these reactions, for example, as a source of 1 O 2 in chemical lasers or in organic synthesis.…”

A new bright chemiluminescent reaction: interaction of acetone with solid potassium peroxymonosulfate in the complex of europium nitrate

“…8,9 Moreover, dioxiranes belong to a new class of hyperenergetic peroxides, which produce chemiluminescence (CL) during rearrangement to the corresponding esters 8 or oxidation of organic and inorganic substrates. 10,11 In particular, the study of the dioxirane CL has led to the discovery of a new mechanism of liquid-phase organic reactions, the socalled oxygen-transfer CL. 10 Apart from dioxirane involvement, the Caro's acid-acetone system is a highly efficient source of singlet excited oxygen ( 1 O 2 ), 5 whose importance in environmental and biomedical sciences, chemi-and bioluminescence, as well as in organic synthesis, is now well recognized.…”