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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.

Phosphorescence of methyl acetate formed by isomerization of electron-excited dimethyldioxirane is observed upon excitation at the wavelength of the absorption band of dimethyldioxirane in acetone at 77 K. The quantum yield of the photodeeomposition of dimethyidioxirane at 296 K is equal to 13.1+0.7 tool Einstein -l. The high quantum yield of photolysis is evidence for the chain mechanism of decomposition of dimethyldioxirane.

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The decomposition of dimethyldioxirane (1) in oxygen-free acetone solutions (46 ~ is accompanied by chemiluminescence (CL) in the visible spectral region. The emitter of CL is triplet-excited methyl acetate (2"('I')). For the decomposition of solutions of I in acetone and deuterated dimethyldioxirane in acetone-D 6 the decay of CL follows the first-order kinetics, and the kinetic isotope effect is observed. Two mechanisms of the formation of 2*(T) are discussed: ta) chain-radical process and (b) isomerization of 1 to 2.Key words: organic peroxides, dimethyldioxirane, chemiluminescence, mechanism of chemiluminescence.Formation of excited products in the decomposition accompanied by chemiluminescence (CL) is a general property of several cyclic peroxides. For example, the decomposition of dioxetanes gives ketones in singlet and triplet excited states, i,2 and the decomposition of some ozonides results in the formation of singlet oxygen. 3,4 In the majority of cases, these are precisely the products which are emitters of the luminescence appeared. Cyclic peroxides (dioxiranes 5,6) are not exceptions in this series. The energy released in the decomposition of dioxiranes to the corresponding ester is equal to -80 kcal real -1 al~d, hence, a chemiluminescence process is possible. 5,r In fact, we have shown 8 that the thermal decomposition of dimethyldioxirane (1) in the presence of an activator of CL, 9,10-dibromoanthracene (DBA), results in the appearance of CL caused, as we supposed, by the energy transfer from triplet-excited methyl acetate (2*(T)) (the main product of the decomposition of 1) to DBA. Later, 9 we observed a substantially more intense CL in the decomposition of compound 1 sorbed from the gas phase on the surface of Sitipor. However, zao CL was observed in a solution of i in acetone. We related this fact to the quenching process and, first of all, to the presence of oxygen, an efficient quenching agent of triplet-excited states. In this work, we first report on CL in the thermal decomposition of oxygenfree solutions of 1 in acetone. ExperimentalDioxirane 1 was obtained and analyzed as described in Ref. 10. The kinetics of the decomposition of 1 was monitored spectrophotometrically in a thermostated quartz ceil (the opti-" Dedicated to Prof, W. Adam on the occasion of his 60th birthday.cal path was 1 cm) by the decrease in the optical density at L 335 nm (e 10 L real -I cm-t) t~ on a Specord M-40 instrument (Carl Zeiss, Jena). Chemiluminescence was monitored on an installation of an FEU-140 photomultiplier calibrated in absolute units according to a procedure described previously. It Phosphorescence spectra of methyl acetate (2) were recorded on a Hitachi MPF-4 spectrofluorimeter at 77 K. Oxygen from a solution of 1 in acetone was removed by subsequent "freezing-evacuating-thawing out" procedures repeated 5--6 times until the release of gas bubbles stopped completely. After this, a solution of I in acetone was placed in a therrnostated cell arranged above the photocathode of the photomultiplier, and CL ...

The synthesis and X-ray diffraction established the structure of (7R,8S)-(see text for symbol)-(13R,17R)-trioxolaneabietic acid. Predicted by the computer system PASS antineoplastic activity and the ability to induce apoptosis, a mechanism of cell death, is correlated with experimentally shown cytotoxic activity against malignant cell line MeWo. Results of tests on animals have shown that abietic acid and its 9R,11S-epoxy-12R,15R-trioxolane derivative have anti-inflammatory and antiulcer activity in the absence of adverse effects on animal organisms.