Cyclohexanone oxidation

The study of benzaldehyde and cyclohaxanone co-oxidation showed the formation of s-caprolactone as the main product of cyclohexanone oxidation [5]. Cyclohexanone was found not to react practically with peroxyl radicals under mild conditions. The oxidation of benzaldehyde produces perbenzoic acid. The latter oxidizes the benzaldehyde to benzoic acid and cyclohexanone to s-caprolactone. 

Treatment of 2-butyne with ozone leads to unstable primary ozonides that cleave to cr-oxo-carbonyl oxides these could be trapped in the presence of aldehydes or ketones affording cross- -oxo-l, 2,4-trioxolanes. Subsequent cycloadditions between such cr-oxo-ozonides and cyclohexanone oxide, generated in situ from O-methylcyclohex-anone oxime (which affords methyl nitrite as a side-product), yield cr-diozonides 101 (Scheme 30) <1997J(P1)1601>. 

In a similar reaction various acyloxy-substituted alkynes were ozonolyzed in the presence of O-methylcyclohex-anone oxime affording more complex a-diozonides. An X-ray crystallographic determination revealed that the compound with R1 = Ph and R2 = CH2-0-C0-Ph is a single diastereomer 102 formed by the approach of the cyclohexanone oxide to the carbonyl group of the intermediate bicyclic ozonide from the less hindered exo-face (Scheme 31) <1997J(P1)1601>. 

Oxidation of cyclohexanone. Oxidation of cyclohexanone with TTN in acetic acid at room temperature proceeds rapidly to give adipoin (5) in 84% yield. If the oxidation is performed at first at room temperature, the thallium(I) nitrate removed hy filtration, and then the filtrate heated to about 40° for a few minutes, the product is cyclopentanecarboxylic acid (4), obtained in 84% yield. McKillop et al. propose that both products are derived from a common precursor, an epoxy enol (3). 

The presence of a silica framework with few defects makes TS-1 a highly hydrophobic material suitable for oxidations in the liquid phase with H2O2 as oxidant. Thus, TS-1 has proven to be successful in the oxidation of alcohols, epox-idation of linear olefins, hydroxylation of aromatics, ammoximation of cyclohexanone, oxidation of alkanes to alcohols and ketones, oxidation of amines, oxidation of sulfur-containing compounds, and oxidation of ethers [66-75]. 

The mechanism of cyclohexanol oxidation has been studied in detail and is rather complex [23,26,32,48—50,57,58]. Various reactions involving H202 decomposition and cyclohexanone oxidation play the main part in the later stages of the process. 

The primary product of cyclohexanone oxidation is a-ketohydro-peroxide [130], subsequently converted to diketone, the semialdehyde of adipic acid [130,131], and adipic acid [130,131]. Valeric and caproic acids and caprolactam were detected among the oxidation products [130]. 

The mechanism of cyclohexanone oxidation has been found [275,276] to be more complicated than suggested by Pritzkow [130] and is shown in... 

An ester (probably lactone) and an acid (adipic) are produced in parallel with hydroperoxide in initiated cyclohexanone oxidation at 80—110°C [158]. The peroxy radical is assumed not only to abstract a H atom from the ketone but also to add to the carbonyl group with subsequent decay... 

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