V. V. Shereshovets

Complex of chlorine dioxide with TEMPO and its conversion into oxoammonium salt

Complex formation between chlorine dioxide and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and its thermodynamic characteristics were studied in a number of organic solvents. The complex was shown to transform into the oxoammonium salt. The kinetics of this reaction were studied, and the equilibrium constants of the TEMPOċClO2 complex, determined by direct measurements and from kinetic data, were found to be in good agreement. The electronic structure of the complex is discussed in the light of recent theoretical results. Copyright

Determination of rate constants for quenching singlet oxygen by chemiluminescence technique

Overall rate constants have been found for quenching1O2 generated under thermal decomposition of hydrotrioxides ROOOH, by several unsaturated species at 0°C. CH3CH(OH)OOOHm (CH3)2C(OH)OOOH, CH3C(OC2H5)2OOOH and CH3C(O) CH(OOOH) (CH2)2CH3 were used as ROOOH; unsaturated compounds were 1,3-diphenylisobenzofurane, 2-methylfurane, 2,3,4,5-tetraphenylfurane, furfuroldiacetate, tetramethylethylene, adamantylideneadamantane, exo,-exo-2,3-dioxymethyl-7-adamantylidenenorbornane, exo,-exo-2,3-(21-oxatrimethylene)-7-adamantylidenenorbornane, 1,3-cyclohexadiene, (E,E)-8, 10-dodecadienol, cyclooctatetraene and isoprene.AbstractОпределены брутто константы скорости тушения1O2, генериремого при термическом распаде гидротриоксидов ROOOH рядом ненасыщенных соединений при O°C. В качестве ROOOH использовали CH3CH(OH)OOOH, (CH3)2C(OH)OOOH, CH3C(OC2H5)2OOOH, CH3C(O)CH(OOOH) (CH2)2CH3; ненасышенных соедниений-1,3-дифенилизобензофуран, 2-метилфуран, 2,3,4,5-тетрафенилфуран, фурфуролдиацетат, тетраметилэтилен, адамантилиденадамантан. экзо, экзо-2,3-(21-оксатриметилен)-7-адамантулуденнорборан, 1,3-циклогексадиен, (Э,Э)-8,10-додекадиенол, циклооктатетраен, изопрен.

Theoretical study of the reaction between ozone and C–H bond: gas-phase reactions of hydrocarbons with ozone

Abstract The gas-phase reactions of ozone with C–H bonds in methane, ethane, propane (secondary C–H bond), and isobutane (tertiary C–H bond) have been studied by semiempirical AM1 method. Reactions proceed through biradical transition state and lead to alkyl and hydrotrioxyl HOOO radicals. The latter immediately decomposes into molecular oxygen and hydroxyl radical HO . The formation of hydrotrioxides ROOOH in gas-phase reactions between ozone and hydrocarbons is shown to be highly improbable.

Formation of hydrotrioxides during ozonation of hydrocarbons on silica gel. Decomposition of hydrotrioxides

Hydrotrioxides (HT), ROOOH, from isopentane, 1,4-dimethylcyclohexane, 1,3-dimethylcyclohexane, decalin and triphenylmethane were synthesized for the first time by low-temperature ozonation of the corresponding hydrocarbons on a silica surface. Thermal decomposition of hydrotrioxides is accompanied by the formation of radicals and by infrared and visible chemiluminescence (CL). In solution the HTs form self-associates and react reversibly with the solvent (acetone) producing Bayer–Villiger type intermediates (unsymmetrical dialkyl trioxides). These reactions cause a complex character of the decomposition kinetics of HTs, as evidenced by monitoring the dependence of CL intensity on time. Activation parameters of thermal decomposition of HTs show a compensation effect (logA vs EA) which describes well the available experimental and theoretical data for the homolysis of organic trioxides. Copyright

Chemiluminescence in the thermal decomposition of di(tert-butyl) trioxide

Intense chemiluminescence (CL) in the visible and IR regions arising during the thermal decomposition of di(tert-butyl) trioxide has been observed. The decomposition rate constants have been determined. The emitter of CL in the IR region is singlet oxygen, that of CL in the visible region is triplet excited acetone. Kinetic and spectral data and thermochemical and MNDO calculations point to a homolytic mechanism of decomposition. The formation of the CL emitters occurs in the reactions of radicals that arise upon the decay of di(tert-butyl) trioxide.

Interaction of chlorine dioxide with nitroxyl radicals

The formation of charge transfer complexes between chlorine dioxide and nitroxyl radicals (2,2,6,6-tetramethylpiperidin-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidin-1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidin-1-oxyl, 4-acetylamido-2,2,6,6-tetramethylpiperidin-1-oxyl, 2,2,5,5-tetramethyl-4-phenyl-3-imidazolin-1-oxyl, and bis(4-methoxyphenyl) nitroxide) in acetone, acetonitrile, n-heptane, diethyl ether, carbon tetrachloride, toluene, and dichloromethane was found by spectrophotometry at –60—+20 °C. The thermodynamic parameters of complex formation were determined. The radical structure affects its complex formation ability. The charge transfer complex is transformed into the corresponding oxoammonium salt.

Oxidation of diterpenoid alkaloids with dimethyldioxirane

Oxidation of diterpene alkaloids by dimethyldioxirane was studied with eldeline, talatizamine, aconitine, and zongorine as examples. Nitrones and 19-oxo derivatives of bases were obtained. The results of the oxidation allow one to draw an analogy with the oxidation by KMnO4 and to suggest a mechanism of the reaction.

ESR studies of radical breakdown for di-t-butyl trioxide

ESR data show thermal breakdown of the title trioxide into peroxy and alkoxy radicals ROO. and RO., respectively. Equilibrium constants were calculated for the formation of tetroxide ROOOOR from two peroxy radicals. Their thermodynamic parameters were determined at temperatures ranging within 193–173 K.

Induced decomposition of di(tert-butyl)trioxide

Thermal decomposition of di(tert-butyl)trioxide (ButOOOBut) in a wide range of concentrations was studied by visible and IR chemiluminescence. Induced decomposition of ButOOOBut caused by its reaction with the peroxy radicals formed in the solvent (CH2Cl2) was found and investigated.

Studies of decomposition kinetics for ozone complexes with cumene and chlorobenzene

Kinetic regularities in decomposition of complexes of aromatic compounds with O3 have been studied for ozone complexes with cumene and chlorobenzene. Oxidation effect of these complexes on both aromatic compounds and olefins has been established.AbstractНа примере комплексов озона с кумолом и хлорбензолом изучены кинетические закономерности распада комплексов ароматических соединений с O3. Обнаружено окислительное действие комплексов по отношению к ароматическим соединениям и олефинам.