Epoxidation of cyclooctene

Scheme 2 Epoxidation of cyclooctene catalyzed by Fe(BPMEN) and Fe(TPA) complexes...

T able 2 Epoxidation of cyclooctene with iron catalysts and H2O2... 

Epoxidation of cyclooctene and other alkenes with Oxone (KHSO5) was promoted effectively in an aqueous micellar solution of an amphiphilic ketone (3.3).52 The amphiphilic ketone can be easily derived from hepta(ethylene glycol) monodecyl ether. 

Srinivasan and Ford [158] reported that epoxidation of cyclooctene using excess H202 was catalyzed by polymolybdate such as [Mo7024]6 tethered on the colloidal polymer with alkylammo-nium cations. Cyclooctene was oxidized to give 1,2-epoxy cyclooctane with >99% selectivity at 90% conversion for 24 h at 313 k ... 

In the case of supported Venturello catalyst of [(C6H13)4N]3[P04 W0(02)2 4], epoxidation of cyclooctene was performed by using 30% aqueous H202 without organic solvents ... 

Anotlier example of dendritic POM complexes used as recoverable oxidation catalysts was reported by Plault et al. (SS). A series of ionic polyammonium dend-rimers containing between 1 and 6 POM units were prepared and used to catalyze the epoxidation of cyclooctene in a biphasic water/CDCls system. A comparison of the homogeneous mono-, bis-, tris-, and tetra(POM) catalysts indicated that there was no dendritic effect on the reaction kinetics within this series. However, a dendritic effect was found in the recovery of the catalysts. The dendritic catalysts were precipitated from the organic phase by addition of pentane. The recovery of the tri-and tetra-(POM) catalysts was easier (80—85% and 96%, respectively) than that of the mono(POM) catalyst. 

Supported iron porphyrins are less reactive than the corresponding manganese derivatives in the PhIO epoxidation of cyclooctene. 80% of olefin conversion was reached with MnBrgTMPS-PVP in 2 h, whereas only 10% was obtained with FeBrgTMPS-PVP in 6 h. 

Recycling experiments with MnClj2TMPS immobilized on methylated PVP, Recycling experiments were performed by re-using four times the same MnQi2TMPS catalyst supported on methylated PVP in the PhIO epoxidation of cyclooctene. For [MnCli2TMPS-PVPMe ][TsO"], it should be noted that the first two cycles are exactly the same, only a small activity decrease is observed for the third run. With 1 jimol of MnCli2TMPS immobilized on [PVPMe "][TsO ] the total epoxide production after 4 runs is 1970 jimol. The overall selectivity based on PhIO is 65%. ... 

Epoxidation of cyclooctene has been shown, using ozone in water where the products were easily recovered by phase separation (Shu et al., 1995). 

Gold-catalyzed oxidation of styrene was firstly reported by Choudhary and coworkers for Au NPs supported on metal oxides in the presence of an excess amount of radical initiator, t-butyl hydroperoxide (TBHP), to afford styrene oxide, while benzaldehyde and benzoic acid were formed in the presence of supports without Au NPs [199]. Subsequently, Hutchings and coworkers demonstrated the selective oxidation of cyclohexene over Au/C with a catalytic amount of TBHP to yield cyclohexene oxide with a selectivity of 50% and cyclohexenone (26%) as a by-product [2]. Product selectivity was significantly changed by solvents. Cyclohexene oxide was obtained as a major product with a selectivity of 50% in 1,2,3,5-tetramethylbenzene while cyclohexenone and cyclohexenol were formed with selectivities of 35 and 25%, respectively, in toluene. A promoting effect of Bi addition to Au was also reported for the epoxidation of cyclooctene under solvent-free conditions. 

Epoxidation of cyclooctene with hydrogen peroxide, catalysed by the methoxide-ligated form of iron(III) tetrakispentafluorophenyl [F20TPPFe(III)] porphyrin, is proposed to involve a reaction of F20TPPFe(in) with hydrogen peroxide to form an iron(III) hydroperoxide species, which then undergoes both heterolytic and homolytic cleavage to form iron(IV) n -radical cations and iron(IV) oxo species, respectively. 

The iron(IV) r-radical cations are responsible for the epoxidation of cyclooctene, whereas the iron(IV) oxo species are responsible for the decomposition of hydrogen peroxide (Scheme 7).175... 

As a catalytic test reaction, the epoxidation of cyclooctene with t-BuOOH was studied. Although the complex leaches from an Al-containing MCM-41,... 

Recently, isolated dioxoMo entities were docked onto the surfaces of ordered mesoporous materials such as MCM-41 and MCM-48. Mo grafting was performed by impregnation of the calcined and dehydrated silica with Mo02X(THF)2 (with X = Br or Cl) in dry dichloromethane. The resulting supported Mo complexes catalyzed the epoxidation of cyclooctene... 

Organonitrile-functionalized mesoporous silicas such as MCM-41 and MCM-48 have been used to immobilize dioxoMo(VI) complexes such as Mo02X2(THF)2 (with X = Br or Cl) (218). The catalytic potential of these hybrid material was evaluated for the epoxidation of cyclooctene with r-BuOOH as the oxygen source. Notwithstanding the high activities claimed, pronounced Mo leakage was observed. Indeed, it was shown that cyclooctene continued to be converted after the solid catalyst was removed from the reaction mixture (218). 

Thus, the substituted heteropolyanion is stable and active even in the presence of oxidants such as /-BuOOH or PhIO. Note that the heteropolyanion is unstable with respect to hydrogen peroxide. Based on the high stability, TMSP can be used for alkane hydroxylation [67b]. Mansuy et al. have reported that P2Wn06i (Mn3+ Br)8 is oxidation resistant and more active for the epoxidation of cyclooctene with PhIO than those containing Fe3+, Co2+, Ni2+, or Cu2+ [68]. The oxygenations of cyclohexane, adamantane, and heptane and the hydroxylation of naphthalene, are also catalyzed by TMSP. 

A large range of different ionic liquids have been screened in the epoxidation of cyclooctene with dioxomolybdenum(VI) complexes and ferf-butyl hydrogenperoxide as oxidant, as shown in Table 5.2.[32] With the diazabutadiene complex, 48, as catalyst, inferior turnover frequencies were observed relative to the reaction in neat substrate or in dichloromethane and the recycling potential of the catalyst turned out to be only limited. Catalyst immobilisation was better with the cationic tris(methylaminomethyl)ethane complex, 49, however at the expense of selectivity. Of the ionic liquids tested, [C4Ciim][Tf2N] gave the best results for both molybdenum complexes. 

Table 5.2 Epoxidation of cyclooctene with TBHP as oxidant and Mo-complexes 48 and 49 as catalysts...

C4Ciim][BF4] MoCp-complexes TBHP Epoxidation of cyclooctene product extracted with hexane activity under biphasic [33]... 

N. A. Stephenson, A. T. Bell, Effects of methanol on the thermodynamics of iron(III) [tetrakis (pentafluorophenyl)]porphyrin chloride dissociation and the creation of catalytically active species for the epoxidation of cyclooctene, Inorg. Chem. 45 (2006) 5591. 

No stoichiometric epoxidation of cyclooctene with the isolated compoimd 3b proceeded, showing that 3b is inactive for the present epoxidation. An induction period (30 min) was still observed for the epoxidation catalyzed by 3b with H2O2... 

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