Cyclohexanone oxime reduction

The only other nitroparaffin manufactured on a large scale was nitrocyclohexane [1122-60-7] made by Hquid-phase nitration of cyclohexane. Nitrocyclohexane was the starting material for S-caprolactam via reduction to cyclohexanone oxime. This process has been superseded by other, more efficient processes (see Caprolactam). Nitrocyclohexane is not being produced ia large quantities for either captive use or sale. 

Reduction of cyclohexanone oxime with lithium aluminum hydride in tetra-hydrofuran gave cyclohexylamine in 71% yield [809], and reduction of ketoximes with sodium in methanol and liquid ammonia [945] or in boiling ethanol [946] afforded alkyl amines, usually in good to high yields. Stannous chloride in hydrochloric acid at 60° reduced the dioxime of 9,10-phenanthra-... 

Pyrrolidone is a lactone used for the production of nylon-4. This reactant may be produced by the reduction ammoniation of maleic anhydride. s-Caprolactam, used in the production of nylon-6, may be produced by the Beckman rearrangement of cyclohexanone oxime (structure 17.11). The oxime may be produced by the catalytic hydrogenation of nitrobenzene, the photolytic nitrosylation of cyclohexane (structure 17.9), or the reaction of cyclohexanone and hydroxylamine (structure 17.10). Nearly one-half of the production of caprolactam is derived from phenol. 

Various procedures have been developed for the production of oximes from nitroparaffins. Direct reduction with zinc dust and acetic acid has been proposed, but the yields are poor because of the simultaneous formation of amines. A synthesis for cyclohexanone oxime has been demonstrated which involves the formation and selective hydrogenation of 1-chloro-l-nitrocyclohexane. The halogenated intermediate is prepared in quantitative yield by chlorination of the sodium salt of acz -nitrocyclo-hexane, and subsequent hydrogenation is performed in an 80% yield over palladium-on-charcoal, ... 

Low-valent metal salts have been used to bring about reductive cleavage of oximes. Corey and Rich-man used chromium(II) acetate to convert O-acetyl ketoximes into imines, which were hydrolyzed to ketones. " Aqueous titanium(III) chloride and vanadium(II) salts also reduce oximes again, the imines are usually hydrolyzed in situ, but some hindered imines, such as compound (37), are isolable." A method of preventing hydrolysis is to carry out the reduction in anhydrous conditions in the presence of an acylating agent. The products of such reactions, when applied to oximes of enolizable ketones, are en-amides. For example, these ketoximes are converted into A/-formylenamines when heated in acetonitrile with anhydrous titanium(III) acetate and acetic formic anhydride cyclohexanone oxime gives the en-amide (38 97% Scheme 22)." This type of reduction has been used by Barton and coworkers to prepare enamides from steroidal oximes. They reported that the reaction could be performed by acetic... 

The TS-1 catalyzed hydroxylation of phenol to a 1 1 mixture of catechol and hydroquinone has already been commercialized by Enichem. Another reaction of considerable commercial importance is the ammoximation of cyclohexanone to cyclohexanone oxime, an intermediate in the manufacture of caprolactam. It could form an attractive alternative to the established process that involves a circuitous route via oxidation of ammonia to nitric acid followed by reduction of the latter to hydroxylamine (see Fig. 10). The ammoximation route employs a more expensive oxidant (H202) but is shorter and produces considerably less salt. However, we note that is does not provide a complete solution to the salt problem as substantial amounts are also produced in the subsequent Beckmann rearrangement of the oxime. The answer to this problem is probably also in the deployment of an efficient solid catalyst. 

In a process developed to commercial maturity by DuPont, and industrially practiced by this company from about 1963 to 1967 [121], cyclohexanone oxime is obtained by a route that encompasses the nitration of cyclohexane to nitrocyclohexane and the reduction of the latter to the oxime, which is converted to caprolactam by the Beckmann rearrangement. According to U.S. Patent 2,634,269, nitrocyclohexane can be converted directly to caprolactam in the gas phase at 25(F450°C using a polyborophosphate catalyst. 

Cyclohexanone oxime undergoes slow reduction to N-cyclohexylhydroxyl-amine. Phenylisocyanate undergoes rapid reduction to the amine stage, and further reduction is very slow. 

Azobenzene is inert, whereas azoxybenzene is reduced very sluggishly. However, both are reduced very rapidly by lithium triethylborohydride [19]. No reduction is observed of cyclohexanone oxime, which means it provides another method for protection of the carbonyl group toward Li 9-BBNH [18]. 

The synthesis of aziridines by the reduction of ketoximes with lithium aluminium hydride or sodium aluminium (dimethoxyethoxy) hydride ( Red-AI ) is possible when the oxime has a neighbouring double bond or phenyl group cyclohexanone oximes give amines under these conditions. A new simple, and rapid aziridine synthesis from cyclohexanones uses the above reducing agents on the trimethyl... 

In the DSM HPO process, nitrate ions are reduced to hydroxylamine using a palladium/carbon catalyst in an aqueous phosphate buffer solution. It was possible to prepare cyclohexanone oxime by a process involving the extraction of cyclohexanone from solution in toluene, into an immiscible aqueous solution of hydroxylamine in a two phase liquid reactor. The spent solution was then recycled with added nitric acid to the reduction step and sulfate production was eliminated ... 

Although the metal-NHs reduction of unhindered cyclohexanones usually affords equatorial alcohols with greater stereoselectivity then metal hydride reductions, this method has not been used frequently in synthesis. An exception is the highly stereoselective reduction of ketoxime (19 equation 10), an intermediate in the synthesis of ( )-perhydrohistrionicotoxin, which gave an excellent yield of equatorial alcohol (20) on reduction with Na-NHs. This reduction is noteworthy in that the oxime survives the reduction, which was carried out below the boiling point of liquid NH3 for a relatively short period of time (30 min). ... 

Another method for reductive amination of carbonyl compounds is based on the electroreduction of oximes in aqueous media. Thus, sugar oximes were reduced to their corresponding glycamines in good yields (Hg, KCl, acetate buffer). Similar reductions of oximes derived from furfural, salicylaldehyde, benzophenone and cyclohexanone have also been described, " but reports of preparative electrolyses in strictly aprotic media seem to be absent in the literature. 

Nylon 6, commonly known as Perlon, in which the repeating units always contain six carbon atoms, is obtained by the polymerization of caprolactam. The first stage, as with the manufacture of nylon 66, is the reduction of phenol to cyclohexanol, which is converted into cyclohexanone by oxidation. The latter reacts with hydroxylamine to form an oxime. 

Alternative syntheses of a-lycorane (23) and y-lycorane (25) depend on the preparation of unsaturated lactams (20) and (21) whereby ring c is derived from an aryl-cyclohexanone (17) (Scheme 2). Reduction of the oxime of the 2-... 

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