New insights into the reaction of t-butylhydroperoxide with dichloro- and dimethyl(dioxo)molybdenum(VI)

Groarke, Michelle; Gonçalves, Isabel S.; Herrmann, Wolfgang A.; Kühn, Fritz E.

doi:10.1016/s0022-328x(02)01134-8

Cited by 53 publications

(25 citation statements)

References 14 publications

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“…Progressively, the reaction rate decreases, which may result from the formation of tert-butyl alcohol (a by-product of the epoxidation), which competes with TBHP for coordination to the Mo VI centre (Scheme 1). 10,11 Interestingly, the reaction rate of cyclooctene epoxidation is roughly the same for both catalysts. The initial activities of 1 and 2 are 179 and 174 mol mol…”

Section: Catalytic Epoxidation Of Cis-cyclooctenementioning

confidence: 87%

“…10 A mechanism has been proposed in which the HOO proton is transferred to one of the terminal oxygen atoms and the À OOR group coordinates as a seventh ligand in a Z 1 manner to the Mo centre. 10,11 The reaction continues by approach of the olefin to the coordinated a oxygen.Unfortunately, dioxomolybdenum(VI) complexes with polypyridyl ligands (bipy and bpym) are rather slow catalysts of low general activity. Substituted 1,4-diazabutadienes seem to be more promising as supporting ligands.…”

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confidence: 99%

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Dichloro and dimethyl dioxomolybdenum(vi)–diazabutadiene complexes as catalysts for the epoxidation of olefins

et al. 2004

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The dioxomolybdenum(VI) complex [MoO 2 Cl 2 {p-tolyl(CH 3 DAB)}] has been prepared in good yield by reaction of the solvent adduct MoO 2 Cl 2 (THF) 2 with one equivalent of the bidentate ligand N,N-p-tolyl-2,3-dimethyl-1,4-diazabutadiene. Treatment of the dichloro complex with the Grignard reagent CH 3 MgCl gives the dimethyl derivative [MoO 2 (CH 3) 2 {p-tolyl(CH 3 DAB)}]. The complexes are highly active and selective catalysts for the homogeneous epoxidation of cyclooctene using tert-butyl hydroperoxide (TBHP) as the oxidant. In both cases, the initial activity is ca. 175 mol mol À1 Mo h À1 and cyclooctene oxide is obtained quantitatively within 4 h. It was possible to recover the dimethyl complex at the end of the reaction and reuse it in a second run with only a small decrease in activity. The complexes are also active and selective for the epoxidation of other olefins, such as 1-octene, 2-octene, cyclododecene and (R)-(þ)-limonene, with TBHP. The catalytic production of cyclooctene oxide was investigated in detail, varying either the reaction temperature or the initial concentrations of substrate, oxidant and catalyst precursor. Kinetic studies show that the catalyst precursor-oxygen donor complex formation is first-order in TBHP and in the metal complex [MoO 2 Cl 2 {p-tolyl(CH 3 DAB)}]. A specific rate of 3.2 mol À1 dm 3 s À1 was found for catalyst formation at 25 C. Activation parameters for this reaction have also been measured (DH 6 ¼ ¼ 48 AE 3 kJ mol À1 , DS 6 ¼ ¼ À112 AE 10 J mol À1 K À1).

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Section: Catalytic Epoxidation Of Cis-cyclooctenementioning

confidence: 87%

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confidence: 99%

Dichloro and dimethyl dioxomolybdenum(vi)–diazabutadiene complexes as catalysts for the epoxidation of olefins

et al. 2004

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“…Previous studies with complexes of the type MoO 2 Cl 2 L bearing bipyridine ligands (L) have consistently indicated that neither the Mo-Cl bonds nor the Mo-N bonds are disrupted during catalytic olefin epoxidation using TBHP in decane as the oxidant [36,37]. The available experimental and theoretical evidence indicates that the complexes undergo an equilibrium reaction with excess TBHP to give seven-coordinate Mo VI g 1 -alkylperoxo complexes; attempts to isolate these species have been unsuccessful, with the starting compound always being recovered unchanged [36,37]. For complex 4, the fact that the selectivity to the epoxide is always 100% for both catalytic runs is consistent with the complex being stable under the reaction conditions.…”

Section: Catalytic Performance Of 1-3 Using Tbhp As Oxidantmentioning

confidence: 99%

Effect of an Ionic Liquid on the Catalytic Performance of Thiocyanatodioxomolybdenum(VI) Complexes for the Oxidation of Cyclooctene and Benzyl Alcohol

et al. 2009

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The complexes (PPh 4 ) 2 [Mo VI O 2 (NCS) 4 ] (1), Mo VI O 2 (NCS) 2 (di-tBu-bipy) (2) and Mo 2 VI O 5 (NCS) 2 (di-t Bu-bipy) 2 (3) (di-tBu-bipy = 4,4 0 -di-tert-butyl-2,2 0 -bipyridine) were studied as catalyst precursors for the oxidation of cyclooctene (Cy8) and benzyl alcohol (BzOH), using either dimethyl sulfoxide (DMSO) or tert-butyl hydroperoxide (TBHP) as oxidant. By dissolving complex 2 in the room temperature ionic liquid 1-butyl-3-methylpyridinium tetrafluoroborate, the catalytic performance with TBHP was improved (higher selectivity to the aldehyde and higher Cy8 conversions). For Cy8 oxidation, the unreacted substrate and products were easily extracted with n-hexane, and the ionic phase containing the catalyst could be reused without loss of catalytic performance.

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“…The interaction of hydrogen bonds in organic solids has been utilized in the construction of a variety of supramolecular materials [6], such as molybdenum-based supramolecular networks. These molybdenum-based supramolecular networks differ from the previous molybdenum (VI) complexes containing the cis-MoO 2 fragment, such as MoO 2 X 2 (L 1 ) p [7][8][9][10][11][12][13][14][15][16] and MoO 2 X (L 2 ) q (L 1 ) r [17][18][19] (X = F, Cl, Br or CH 3 ; L = mono or bidentate neutral (L 1 ) or anionic (L 2 ) ligand; p = 2, q ? r = 3) containing coordinative bonds and a bond between Mo and organic ligands (L 1 or L 2 ).…”

Section: Introductionmentioning

confidence: 99%

Two hydrogen-bond-cross-linked molybdenum (VI) network polymers: synthesis, crystal structures and cyclooctene epoxidation with H2O2

Wang

Shi

et al. 2009

Struct Chem

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Two molybdenum (VI) hydrogen-bonded network polymers [MoO 2 F 4 ]Á(4,4 0 -H 2 bpd)(H 2 O) 2 (1) and [MoO 2 Cl 3 (H 2 O)]Á(4,4 0 -H 2 bpd)Cl (2) (bpd = bipiperidine) have been synthesized and examined as catalysts for epoxidation of cyclooctene. Complexes of the Mo compounds containing the bpd ligand are prepared and characterized by infrared spectroscopy, thermogravimetric and elemental analyses. They have been structurally characterized by single crystal X-ray diffraction analysis. The structures of both the complexes are shown to be comprised of molybdenum and two protonated N-ligand cations that have resulted in a crosslinked hydrogen-bonded network structure. These complexes are applicable as catalysts for the cis-cyclooctene epoxidation reactions with hydrogen peroxide as a source of oxygen and NaHCO 3 as a cocatalyst. It has been observed that the formation of the oxidant peroxymonocarbonate ion, HCO 4 -by hydrogen peroxide and bicarbonate enhances the epoxidation reaction. Both the complexes have exhibited a good activity and a very high selectivity for the formation of cyclooctene oxide.

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New insights into the reaction of t-butylhydroperoxide with dichloro- and dimethyl(dioxo)molybdenum(VI)

Cited by 53 publications

References 14 publications

Dichloro and dimethyl dioxomolybdenum(vi)–diazabutadiene complexes as catalysts for the epoxidation of olefins

Dichloro and dimethyl dioxomolybdenum(vi)–diazabutadiene complexes as catalysts for the epoxidation of olefins

Effect of an Ionic Liquid on the Catalytic Performance of Thiocyanatodioxomolybdenum(VI) Complexes for the Oxidation of Cyclooctene and Benzyl Alcohol

Two hydrogen-bond-cross-linked molybdenum (VI) network polymers: synthesis, crystal structures and cyclooctene epoxidation with H2O2

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