Hydrogen peroxide cyclooctenes

The reaction is usually performed at low temperatures, and sometimes water has been used as solvent. For example, cyclooctene is ozonized in the presence of an emulsifier (polyoxyethylated lauryl alcohol) with aqueous alkaline hydrogen peroxide to give a,co-alkanedi-carboxylic acid in one pot (Eq. 3.21).91... 

Pentadentate dispidine-based Fe(II) complexes catalyse the oxidation of cyclooctene with hydrogen peroxide to afford the expected epoxide product, with the reaction... 

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... 

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. 

EPOXIDATION OF OLEFINS BY HYDROGEN PEROXIDE-ACETONITRILE cw-CYCLOOCTENE OXIDE... 

Epoxidation takes place preferentially or more rapidly at electron-rich (i.e., tetraalkylated) double bonds [217]. The reaction is stereospeciflc cis alkenes give cis epoxides, and trans alkenes give trans oxides [211. 1,2-Dimethylcyclopentene is oxidized with peroxybenzoic acid to 1,2-di-inethylcyclopentene oxide in 85% yield [296], and dj-cyclooctene is transformed by hydrogen peroxide into c -cyclooctene oxide in 60-61% yield [1099]. 

The purpose of preparing aliphatic amine oxides is usually their thermal decomposition to cis alkenes and N,N-dialkylhydroxylamines (Cope rearrangement) [156, 161, 1187]. Thus A, A -dimethylcyclohexylmethylamine is oxidized with 30% hydrogen peroxide in methanol to its oxide, whose decomposition at 90-100 °C at 10 mm of Hg and at 160 °C for 2 h furnishes 79-88% of methylenecyclohexane and 78-90% of A, A -dimethylhydroxyl-amine [161], Another example is the preparation of cw-cyclooctene from dimethylcyclooctylamine (equation 502) [1187]. 

R. Rinaldi, J. Sepulveda, U. Schuchardt, Cyclohexene and cyclooctene epoxidation with aqueous hydrogen peroxide using transition metal-free sol-gel alumina as catalyst, Adv. Synth. Catal. 346 (2004) 281. 

N. A. Stephenson, A. T. BeU, Influence of solvent composition on the kinetics of cyclooctene epoxidation by hydrogen peroxide catalyzed by iron(III) [tetrakis(pentafluorophenyl)] porphyrin chloride (I., TPP)I < 1. Inorg. Chem. 45 (2006) 2758. 

In this reaction the aryl butylselenide 53 is oxidized in situ by hydrogen peroxide to the aryl selenic acid. This acid itself is oxidized to the corresponding peracid wich then catalyzes the epoxidation reaction. The catalyst can be reused more than ten times without any decrease in yield nor increase in reaction time. Thus, the epoxidation of cyclooctene was repeated ten times with the same catalyst solution leading to cyclooctene oxide in 90-93% yield within only 1 h. 

Figure 5 shows effect of oxidant on the reactivity of the sol-gel titania/silica catalysts in the epoxidation of cyclooctene. The conversion in the epoxidation of cyclooctene with tert-butyl hydroperoxide sharply increases with reaction time. However, when the oxidant is hydrogen peroxide, the conversion is quite low... 

From the result of iodometric titration, the conversion of hydrogen peroxide is quite high. The nonproductive decomposition of hydrogen peroxide catalyzed by titania/silicas also gives low cyclooctene conversion. 

Cyclooctene was converted to its epoxide (80% conversion) with hydrogen peroxide using this catalyst. 

Neumann and co-workers have used sandwich-type polyoxometalates as catalysts for such reactions.305 The sandwich consists of transition metal ions between two Keggin anions, as in Ki2WZnMn(II)2(ZnW9034)2. In some cases, quaternary ammonium salts were used as the cations to take the catalyst into organic solvents. Sulfides were oxidized to sulfoxides with 30% aqueous hydrogen peroxide in 85-90% yields, with some sulfone also being formed. The system was more than 99% selective in the conversion of cyclooctene to its epoxide. The system also shows good selectivity between double bonds (6.57), probably the result of the bulky anion and the increased electron density in alkyl-substituted double bonds. 

Benzyl phenyl sulphide, norbornene, cw-cyclooctene, and 4-vinyl-1-cyclohexene were obtained from Aldrich and (IS)-(-)-a-pinene from Fluka. Phenyl sulphide was prepared from benzene and sulphur chloride following the literature procedure[9]. Reference samples of sulphoxides and sulphones were prepared by oxidation of sulphides with sodium periodate[10] and hydrogen peroxide[ll] respectively. Reference samples of epoxides were made by following Kaneda et al.[ 2 procedure. Metal phthalocyanines[13] were prepared from appropriate metal salt, 1,2-dicyanobenzene with ammonium molybdate as catalyst and were characterized by elemental analysis. 

Cis cyclooctene (3).2 To ice cooled N,N-dimethylcyclooctylamin 1 (5 0 g, 32 mmol) in MeOH (10 ml), was added over 30 min 35% hydrogen peroxide (10 0 g. 99 mmol). Stirring was continued until the amine had been consumed (24 h). The excess of peroxide was destroyed by stirring with platinum black (0 25 g) for 5 h. The platinum was removed by filtration and the filtrate was concentrated in vacuo to a syrup (max. temp 30-40°C), to give 2. Amine oxide 2 was heated under vacuum (10 mm) in a N2 atmosphere and the temperature was raised 1 -27min. Decomposition and distillation began at 100°C and ended at 130°C. 

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