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

Abstract

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 E A ) which describes well the available experimental and theoretical data for the homolysis of organic trioxides.

Peroxide intermediates of oxidation processes: Organic trioxides

“…An interesting modification of the method for synthesizing HTOs involves the ozonization of organic compounds on a silica gel surface ("dry" ozonization) 46, 134, 147 -149, 151 . This method was used to obtain hydrotrioxides of 1,3-and 1,4-dimethylcyclohexanes, decalin, and adamantane that are not formed under liquid-phase ozonization conditions 46,147,149 . The most natural explanation of the effect of SiO 2 is that the highly polar silica gel surface stabilizes the ionic or radical intermediates of ozonization, which favors the formation of ROOOH even from nonactivated hydrocarbons.…”

“…Elution of ROOOH from silica gel surfaces during the synthesis of HTOs of hydrocarbons on SiO 2 makes it possible to obtain 0.01-0.13 mol L −1 hydrotrioxide solutions 147 . The 1 H NMR spectrum of acetone solutions displays, in addition to absorption of the hydrotrioxide group at δ ∼13, two signals at δ 4.15 and 4.35 that irreversibly disappear upon thawing of the sample.…”

Organic hydrotrioxides

“…A modified procedure for the synthesis of HTO involves ozonisation of organic compounds on the surface of silica gel (the so-called `dry' ozonisation). 18,31,32,38,39 It was used to obtain the hydrotrioxides 11 and 15 ± 19, which could not be prepared in the liquid-phase ozonisation. 18,31,32 Highly polar silica gel surface stabilises the ionic intermediates of the ozonisation reaction, thus favouring the formation of ROOOH even from non-activated hydrocarbons.…”

“…18,31,32,38,39 It was used to obtain the hydrotrioxides 11 and 15 ± 19, which could not be prepared in the liquid-phase ozonisation. 18,31,32 Highly polar silica gel surface stabilises the ionic intermediates of the ozonisation reaction, thus favouring the formation of ROOOH even from non-activated hydrocarbons. It can be hypothesised that `dry' ozonisation will also be convenient for the synthesis of other HTO which cannot be obtained by liquid-phase ozonisation.…”

Geração de ozônio isotopicamente marcado com átomo de oxigênio-18, (18O3), formando oxigênio-18 molecular singlete, 18O2 (1Δg), e modificações na 2'- desoxiguanosina

“…A QL no infravermelho deriva do relaxamento da radiação O 2 ( 1  g ), a qual é gerada diretamente da __________________________________________________________________________ decomposição do ROOOH ou a partir da dismutação dos radicais peroxila (ROO  ). O último processo também emite luz na região visível do espectro, (Avzyanova E. V. et. al.,1999).…”