Liquid-phase oxidation of sulfides by an aluminum (and titanium) tert-butoxide?tert-butyl hydroperoxide system

Dodonov, V. A.; Zaburdaeva, E. A.; Stepovik, L. P.

doi:10.1007/s11172-005-0026-9

Cited by 9 publications

(8 citation statements)

References 15 publications

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“…The energy of formation of the electron excited coordinated dioxygen 5 calculated from the binding energies of ozonide 4 substantially ex ceeds the energy of formation of O 2 ( 1 ∆ g ). 16 In chlorobenzene at room temperature, the yield of oxygen was 85%, while in the presence of fullerene under analogous conditions, the yield of dioxygen was 59%. Therefore, ~26% of the oxygen generated in the system is consumed in the reaction with fullerene.…”

Section: Methodsmentioning

confidence: 99%

“…Being in the coordination sphere of the metal atom, this oxygen oxidizes under mild conditions (20 °C) the C-H bonds of hydrocarbons 12-14 and the N-H bonds of aromatic amines 15 and virtually completely convert sul fides into sulfones. 16 This allowed some sulfides to be proposed as test reagents for electron excited forms of dioxygen in the liquid phase. The total yield of oxygen is 80%.…”

Section: Methodsmentioning

confidence: 99%

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Oxidation of fullerene C60 with the system aluminum tri-tert-butoxide—tert-butyl hydroperoxide

et al. 2008

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Oxidation of fullerene C 60 with the system aluminum tri tert butoxide-tert butyl hydro peroxide, in which electron excited dioxygen is generated, gave a complex mixture of fullerene oxides C 60 O x (x = 1-6). The pathways of their formation were proposed.The preparative synthesis 1 of fullerene C 60 in 1990 gave impetus to investigations of fullerenes and their func tional derivatives obtained, e.g., by oxidation. The major and (in most cases 2 ) sole oxidation product of fullerene C 60 is its monoxide C 60 O. This oxide forms even when the starting fullerene is exposed to atmospheric oxygen in the light (Scheme 1); however, the rate of this reaction is low. Scheme 1Fullerene strongly absorbs in the UV and visible re gions (longest wavelength peak at λ = 620 nm); C 60 passes into a singlet excited state via the h u →t 1u electron transi tion and then into low energy triplet excited state by in tersystem crossing (ISC). The triplet excited state gener ates in air singlet excited dioxygen ( 1 ∆ g ) in the quantum yield φ = 0.96±0.04 at 532 nm. 3 The increase in the con tent and the decomposition of the latter can be monitored by observing phosphorescence in the near IR region at 1268 nm ( 1 ∆ g → 3 Σ g -). In degassed solvents, the lifetime of the triplet excited state of C 60 is limited (133 µs), ending in a radiationless transition into the singlet ground state via vibrational relaxation. 3,4 .Thus, C 60 can serve as an efficient sensitizer for ge neration of singlet excited dioxygen. Note that ground state fullerene C 60 is not oxidized by singlet excited dioxygen. 3,5Deep oxidation of C 60 under the action of dimethyl and methyl(trifluoromethyl)dioxiranes 6,7 gives its mono , di , and trioxides in ~67, 30, and 8% yields, respectively. The oxide C 60 O is formed when m chloroperoxybenzoic acid is used as an oxidant. 8 The maximum yield (35.4%) of monoxide is achieved in a reaction of C 60 with the system methyltrioxorhenium-hydrogen peroxide. 9 Spec troscopic studies have revealed that epoxidation always occurs at the 6,6 double bond; this has been confirmed by quantum chemical calculations. 10 It has been noted 11 that fullerene cannot be regarded as classic fully delocalized aromatic systems; they retain the features of fused planar conjugated π systems with nonequivalent C atoms and the least steric stress. The electronic structure of C 60 allows reversible acceptance of up to six electrons because of the presence of the triply degenerate LUMO (t 1u ), which are higher in energy by 1.5-2.0 eV than the fivefold degenerate HOMO (h u ). 4As reported earlier, 2 the major product of fullerene oxidation is C 60 O; however, the pathways of its formation for most cases have not yet described in the literature.Systems based on aluminum, titanium, and vanadium tert butoxides and tert butyl hydroperoxide are efficient low temperature oxidants. 12-14 These systems in benzene, chlorobenzene, and CCl 4 at room temperature generate electron excited dioxygen via the formation of interme diate trioxides (ozonides) of the abo...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Oxidation of fullerene C60 with the system aluminum tri-tert-butoxide—tert-butyl hydroperoxide

et al. 2008

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“…The choice of Bn 2 S is due to the fact that, on the one hand, no oxidation products of the benzylic C-H bonds were observed upon its interaction with ozonides (Bu t O) n-1 MOOOBu t (n = 3, M = Al; n = 4, M = Ti). 6 On the other hand, it is known 7 that the oxidation of this sulfide with oxygen, under the conditions of radio fre quency discharge or irradiation with a Xe-Hg lamp sen sibilized by zinc tetraphenylporphine, results in its de struction at the C-S bond to benzaldehyde.…”

Section: Methodsmentioning

confidence: 99%

Radical low-temperature oxidation of dibenzyl sulfide with the triphenylbismuth—tert-butyl hydroperoxide system

et al. 2008

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The reaction of Ph 3 Bi with Bu t OOH in a mole ratio of 1 : 3 in hydrocarbon solvents affords the η 2 peroxo complex of triphenylbismuth Ph 3 Bi(η 2 O 2 ) which oxidizes the C-H bonds of the methyl ene group of dibenzyl sulfide. The reaction proceeds via the radical mechanism with the formation of intermediate unstable sulfur containing hydroperoxide. Its decomposition is accompanied by the C-S bond cleavage, resulting in benzaldehyde.Oxygen activation on metallic centers of transition and nontransition metals in low temperature (20 °C) oxida tion is one of the most important problems of organic catalysts. Metal containing compounds of the ozonide type (Bu t O) n-1 MOOOBu t (n = 3, M = Al; 1,2 n = 4, M = Ti 2,3 ) and the bismuth η 2 peroxo complex Ph 3 Bi(η 2 O 2 ) (1) 4,5 serve as the sources of electron ex cited dioxygen. Ozonides are formed upon the reaction of the corresponding metal tert butoxides with tert butyl hydroperoxide 2 in a mole ratio of 1 : 2, whereas η 2 peroxo complex 1 is formed due to the thermal de composition of di(tert butylperoxy)triphenylbismuth 3 at room temperature. Compound 3 is a product of the reaction of triphenylbismuth (4) with hydroperoxide 2 in a mole ratio of 1 : 3 4,5 (Scheme 1). Scheme 1η 2 Peroxo complex 1 selectively oxidizes the methyl ene groups of alkanes to form carbonyl groups via the radical mechanism 4,5 (Scheme 2). Scheme 2Peroxo complex 1 and the ozonides mentioned above are efficient low temperature oxidants of C-H bonds 4 featuring by the reaction conditions and, especially, by the final products. Dioxygen coordinated on the metal atom acts as a direct oxidant.The purpose of the present work is to obtain compar ative data on the reactivity of the peroxide derivatives of bismuth and aluminum in the low temperature (20 °C) oxidation of the C-H bonds in the benzyl group us ing dibenzyl sulfide and ethylbenzene as examples. The choice of Bn 2 S is due to the fact that, on the one hand, no oxidation products of the benzylic C-H bonds were observed upon its interaction with ozonides (Bu t O) n-1 MOOOBu t (n = 3, M = Al; n = 4, M = Ti). 6 On the other hand, it is known 7 that the oxidation of this sulfide with oxygen, under the conditions of radio fre quency discharge or irradiation with a Xe-Hg lamp sen sibilized by zinc tetraphenylporphine, results in its de struction at the C-S bond to benzaldehyde. ExperimentalSolvents (analytical and reagent grade) were purified as follows: benzene and ethylbenzene were distilled over P 2 O 5 (stored above metallic sodium) and chlorobenzene was distilled and stored over Na 2 SO 4 . Dibenzyl sulfide (pure grade) was recrystallized from

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“…Metal-containing peroxide intermediates such as XOOOBu-t (4) [X = (t-BuO) 2 Al, (t-BuO) 3 Ti] and Ph 3 Bi(g 2 O 2 ) demonstrate a high oxidative activity toward C-H bonds in methylene fragments of hydrocarbons and their derivatives. In the first stage reactions form corresponding ketones and hydroxyl derivatives (see Scheme 3).…”

Section: Introductionmentioning

confidence: 99%

Oxygen activation on metallic centers and oxidizing abilities of such oxygen

Zaburdaeva¹,

Dodonov²,

Stepovik³

2007

Journal of Organometallic Chemistry

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Liquid-phase oxidation of sulfides by an aluminum (and titanium) tert-butoxide?tert-butyl hydroperoxide system

Cited by 9 publications

References 15 publications

Oxidation of fullerene C60 with the system aluminum tri-tert-butoxide—tert-butyl hydroperoxide

Oxidation of fullerene C60 with the system aluminum tri-tert-butoxide—tert-butyl hydroperoxide

Radical low-temperature oxidation of dibenzyl sulfide with the triphenylbismuth—tert-butyl hydroperoxide system

Oxygen activation on metallic centers and oxidizing abilities of such oxygen

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