Specific features of the reaction of vanadyl acetylacetonate with tert-butyl hydroperoxide

Stepovik, L. P.; Gulenova, M. V.

doi:10.1134/s1070363209080143

Cited by 10 publications

(13 citation statements)

References 8 publications

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“…The catalyst VO(acac) 2 forms different complexes and experimental studies have been conducted to demonstrate the various transformations VO(acac) 2 undergoes upon treatment with TBHP. VO(acac) 2 is rapidly converted to vanadate esters (VO(OR) 3-x (OOR) x , with R=tert-butyl and x Є ) in presence of TBHP, and the oxidation products were found to be also acidic, just as Hacac [7,21,22]. Upon treating VO(acac) 2 with an excess of TBHP, typically in the proportion of VO(acac) 2 :TBHP > 10 as in mild oxidation conditions (benzene, 20 °C), acetylacetonate (acac)-ligands are eliminated and oxidized.…”

Section: Introductionmentioning

confidence: 99%

“…The most abundant oxidation product of Hacac was found to be acetic acid (HOAc) [7,23]. Furthermore, certain studies have tried to unravel the initial steps in the reaction of VO(acac) 2 with TBHP [7,8]. The active intermediates were widely accepted to be vanadium(+V) alkylperoxo complexes in the VO(acac) 2 /TBHP [4,16,17,22] and VO(acac) 2 /TBHP/ligand [24][25][26][27][28] catalytic systems.…”

Section: Introductionmentioning

confidence: 99%

“…In all cases these reactions are exothermic. The most abundant oxidation product of Hacac was found to be acetic acid (HOAc) [7,23]. Furthermore, certain studies have tried to unravel the initial steps in the reaction of VO(acac) 2 with TBHP [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…Many catalytic systems based on transitionmetal complexes of Mo, Ti, W and V have been reported and found to be very effective and selective for the epoxidation of a wide range of (cyclo)alkenes using hydroperoxides as oxidant [1][2][3]. The reaction chemistry of vanadyl acetylacetonate (VO(acac) 2 ) as catalyst for the oxidation of cyclohexene with hydrogen peroxide or tert-butyl hydroperoxide (TBHP) as oxidant has been the subject of several experimental studies [4][5][6][7][8]. Recently, the homogeneous VO(acac) 2 /TBHP system and the porous metal organic framework type catalyst MIL-47 [9] have been compared for their cyclohexene epoxidation activity and they showed similar conversion patterns [10,11].…”

Section: Introductionmentioning

confidence: 99%

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Mechanistic insight into the cyclohexene epoxidation with VO(acac)2 and tert-butyl hydroperoxide

Vandichel

Leus

Voort

et al. 2012

Journal of Catalysis

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The epoxidation reaction of cyclohexene is investigated for the system vanadyl acetylacetonate (VO(acac) 2 ) as catalyst with tert-butyl hydroperoxide (TBHP) as oxidant with the aim to identify the most active species for epoxidation and to retrieve insight into the most plausible epoxidation mechanism. The reaction mixture is composed of various inactive and active complexes in which vanadium may either have oxidation state +IV or +V. Inactive species are activated with TBHP to form active complexes. After reaction with cyclohexene each active species transforms back into an inactive complex which may be reactivated again. The reaction mixture is quite complex containing hydroxyl, acetyl acetonate, acetate or a tert-butoxide anion as ligands and thus various ligand exchange reactions may occur among active and inactive complexes. Also radical decomposition reaction allow transforming V +IV to V +V species. To obtain insight into the most abundant active complexes, each of previous transformation steps has been modeled through thermodynamic equilibrium steps. To unravel the nature of the most plausible epoxidation mechanism, first principle chemical kinetics calculations have been performed on all proposed epoxidation pathways. Our results allow to conclude that the concerted Sharpless mechanism is the preferred reaction mechanism and that alkylperoxo species V +IV O(L)(OOtBu) and V +V O(L 1 )(L 2 )(OOtBu) species are most abundant. At the onset of the catalytic cycle vanadium +IV species may play an active role but as the reaction proceeds, reaction mechanisms that involve vanadium +V species are preferred as the acetyl acetonate is readily oxidized. Additionally an experimental IR and kinetic study has been performed to give a qualitative composition of the reaction mixture and to obtain experimental kinetic data for comparison with our theoretical values. The agreement between theory and experiment is satisfactory.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanistic insight into the cyclohexene epoxidation with VO(acac)2 and tert-butyl hydroperoxide

Vandichel

Leus

Voort

et al. 2012

Journal of Catalysis

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“…8 The subsequent formation of the cyclohexane-1,2-diol can be explained by opening of the epoxide ring by an acid catalyzed hydrolysis mechanism. 9 In the MIL-47, a small fraction of terephthalic acid is anticipated to catalyze the opening of the epoxide ring.…”

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confidence: 99%

The remarkable catalytic activity of the saturated metal organic framework V-MIL-47 in the cyclohexene oxidation

et al. 2010

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The remarkable catalytic activity of the saturated metal organic framework MIL-47 in the epoxidation of cyclohexene is elucidated by means of both experimental results and theoretical calculations.Metal organic frameworks (MOFs) are crystalline porous solids composed of a three-dimensional network of metal ions held in place by multidentate organic molecules. 1,2 Recently, the catalytic applications of MOFs have been reviewed by Hupp et al. and Farrusseng et al. 3,4 However, catalytic reaction mechanisms in metal organic frameworks and in particular at saturated coordinated centres are still poorly understood.In this study, we describe the high catalytic activity of a coordinative saturated V-MOF in the liquid phase oxidation of cyclohexene. The metal organic framework MIL-47 consists of a porous terephthalate framework built from infinite chains of V 4+ O 6 octahedra and has a three-dimensional orthorhombic structure that exhibits large pores. 5 Every structure unit in MIL-47 contains an O-V +IV -O bridge. The linkage of the V +IV to dicarboxylate groups of the terephthalate linkers results in an octahedral structure unit. Hence each vanadium(+IV) centre is saturated.The selective oxidation of cyclohexene is particularly interesting as it can yield, depending on the catalyst and the reaction conditions, several products as shown in Scheme 1. In this study, the reaction was carried out with tert-butyl hydroperoxide (70 wt% TBHP in water) as oxidant and chloroform as solvent. The internal standard used was 1,2,4-trichlorobenzene. The molar ratios were chloroform : cyclohexene : TBHP : 1,2,4-trichlorobenzene = 462 : 1 : 2 : 1. The reaction temperature was kept constant at 323 K. Samples were taken out from the reaction mixture at certain times and analyzed by gas chromatography. Next, MIL-47 was compared with a homogeneous vanadium catalyst vanadyl acetylacetonate VO(acac) 2 . Prior to the reaction, all the catalysts were dried under vacuum. Blank tests were performed without catalyst and no cyclohexene conversion was observed. Fig. 1 depicts the cyclohexene conversion and the detailed product distributions for MIL-47 and the homogeneous VO(acac) 2 catalyst. In both reactions, we used an identical amount of V-sites (0.4 mmol, 0.095 g MIL-47 and 0.106 g VO(acac) 2 ). The four main reaction products formed are cyclohexene oxide 2, cyclohexane-1,2-diol 3, tert-butyl-2-cyclohexenyl-1-peroxide 4 and 2-cyclohexen-1-one 5. From these figures it can be seen that the homogeneous catalyst VO(acac) 2 and the MIL-47 show high reaction rates for the conversion of cyclohexene. The initial turnover frequencies considered at the first 20 min are 57 h À1 and 43 h À1 for the VO(acac) 2 and the MIL-47 respectively. Both catalysts showed an almost linear conversion rate during the first 2 h of reaction and finally topped out at 60% conversion. The turnover numbers calculated at the end of the reaction were 62 and 68 for VO(acac) 2 and MIL-47 respectively. Moreover, considering the product distributions, truly interesting similaritie...

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Peroxide intermediates of oxidation processes: Organic trioxides

Khursan

2014

Patai's Chemistry of Functional Groups

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The review discusses the results of studies on the chemistry of organic trioxides ROOOR (R = H or an organic radical) carried out in the past years. The spectral identification, structure, thermal stability and chemical properties of HOOOH, HOOO ⋅ , hydrotrioxides, open‐chain and cyclic trioxides (including fullerene ozonides) are described. The significance of trioxides for biochemistry, environmental chemistry, and organic synthesis is much higher than it was believed previously. The chemical reactions that these compounds undergo resemble those of peroxides. However, the temperature range in which trioxide reactions occur is shifted considerably towards low temperatures. Homolytic decomposition at one of the OO bonds is the most typical reaction of trioxides. Trioxides are liable to induced and catalytic decomposition. Hydrotrioxides demonstrate high oxidative activity. Decomposition of some trioxides is accompanied by efficient generation of singlet oxygen.

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Specific features of the reaction of vanadyl acetylacetonate with tert-butyl hydroperoxide

Cited by 10 publications

References 8 publications

Mechanistic insight into the cyclohexene epoxidation with VO(acac)2 and tert-butyl hydroperoxide

Mechanistic insight into the cyclohexene epoxidation with VO(acac)2 and tert-butyl hydroperoxide

The remarkable catalytic activity of the saturated metal organic framework V-MIL-47 in the cyclohexene oxidation

Peroxide intermediates of oxidation processes: Organic trioxides

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