Cyclohexanol oxime

Dutch State Mines (Stamicarbon). Vapor-phase, catalytic hydrogenation of phenol to cyclohexanone over palladium on alumina, Hcensed by Stamicarbon, the engineering subsidiary of DSM, gives a 95% yield at high conversion plus an additional 3% by dehydrogenation of coproduct cyclohexanol over a copper catalyst. Cyclohexane oxidation, an alternative route to cyclohexanone, is used in the United States and in Asia by DSM. A cyclohexane vapor-cloud explosion occurred in 1975 at a co-owned DSM plant in Flixborough, UK (12) the plant was rebuilt but later closed. In addition to the conventional Raschig process for hydroxylamine, DSM has developed a hydroxylamine phosphate—oxime (HPO) process for cyclohexanone oxime no by-product ammonium sulfate is produced. Catalytic ammonia oxidation is followed by absorption of NO in a buffered aqueous phosphoric acid... 

Cyclohexanone purity is most readily deteanined by gas-Hquid chromatography over DC-710 or carbowax 20M-on-chromosorb. Impurities such as cyclohexane, ben2ene, cyclohexanol, and phenol do not interfere. In the absence of other carbonyl compounds cyclohexanone may be deterrnined by treatment with hydroxylamine hydrochloride, which forms the oxime, as follows ... 

Therefore, CL and die depolymerized product from which CL is regenerated contain various impurities which are present in widely fluctuating amounts depending on the reclamation processes involved. In particular, the presence of cyclohexanone, cyclohexanone oxime, octahydrophenazine, aniline, and other easily oxidized compounds affects die permanganate number. Also volatile substances such as aniline, cyclohexylamine, cyclohexanol, cyclohexanone, nitrocy-clohexanone, and aliphatic amines may also be present in the CL.22... 

It can be obtained from cyclohexane. Cyclohexane is air oxidised to yield a mixture of cyclohexanol and cyclohexanone. Cyclohexanol is dehydrogenated to cyclohexanone over copper catalyst. Cyclohexanone when treated with hydroxylamine sulphate at 20°-95°C gives an oxime. The oxime when treated with concentrated sulphuric acid undergoes Beckmann rearrangement to yield caprolactam. 

The common name caprolactam comes from the original name for the Ce carboxylic acid, caproic acid. Caprolactam is the cyclic amide (lactam) of 6-aminocaproic acid. Its manufacture is from cyclohexanone, made usually from cyclohexane (58%), but also available from phenol (42%). Some of the cyclohexanol in cyclohexanone/cyclohexanol mixtures can be converted to cyclohexanone by a ZnO catalyst at 400°C. Then the cyclohexanone is converted into the oxime with hydroxylamine. The oxime undergoes a very famous acid-catalyzed reaction called the Beckmann rearrangement to give caprolactam. Sulfuric acid at 100-120°C is common but phosphoric acid is also used, since after treatment with ammonia the by-product becomes... 

Caprolactam is discussed more completely in Chapter 11, Section 5. It is made from cyclohexane by oxidation to cyclohexanone-cyclohexanol mixture, formation of cyclohexanone oxime, and acid-catalyzed rearrangement. 

Caprolactam [105-60-2] (2-oxohexamethylenimine, hexahydro-2.fi-azepin-2-one) is one of the most widely used chemical intermediates. However, almost all of the annual production of 3.0 x 106 t is consumed as the monomer for nylon-6 fibers and plastics (see Fibers survey Polyamides, plastics). Cyclohexanone, which is the most common organic precursor of caprolactam, is made from benzene by either phenol hydrogenation or cyclohexane oxidation (see Cyclohexanol AND cyclohexanone). Reaction with ammonia-derived hydroxylamine forms cyclohexanone oxime, which undergoes molecular rearrangement to the seven-membered ring 8-caprolactam. 

Mechanisms have been suggested for the N-bromosuccinimide (NBS) oxidation of cyclopentanol and cyclohexanol, catalysed by iridium(III) chloride,120 of ethanolamine, diethanolamine, and triethanolamine in alkaline medium,121 and for ruthenium(III)-catalysed and uncatalysed oxidation of ethylamine and benzylamine.122 A suitable mechanism has been suggested to explain the break in the Hammett plot observed in the oxidation of substituted acetophenone oximes by NBS in acidic solution.123 Oxidation of substituted benhydrols with NBS showed a C-H/C-D primary kinetic isotope effect and a linear correlation with er+ values with p = —0.69. A cyclic transition state in the absence of mineral acid and a non-cyclic transition state in the presence of the acid are proposed.124 Sulfides are selectively oxidized to sulfoxides with NBS, catalysed by ft-cyclodextrin, in water. This reaction proceeds without over-oxidation to sulfones under mild conditions.125... 

Caprolactam is usually manufactured from cyclohexanone, made by the oxidation of cyclohexane or by the hydrogenation/oxidation of phenol (Fig. 1), although the manufacture can be an integrated process with several starting materials (Fig. 2). The cyclohexanol that is also produced with the cyclohexanone can be converted to cyclohexanone by a zinc oxide (ZnO) catalyst at 400°C. The cyclohexanone is converted into the oxime with hydroxylamine, which then undergoes rearrangement to give caprolactam. 

Several oxidative routes are available to change cyclohexane to cyclohexanone, cyclohexanol, and ultimately to adipic acid or caprolactam. If phenol is hydrogenated, cyclohexanone can be obtained directly this will react with hydroxylamine to give cyclohexanone oxime that converts to caprolactam on acid rearrangement. Cyclohexane can also be converted to adipic acid, then adiponitrile, which can be converted to hexamethylenedi-amine. Adipic acid and hexamethylenediamine are used to form nylon 6,6. This route to hexamethylenediamine is competitive with alternative routes through butene. 

Cyclohexane NOC1 Cyclohexanol, cyclohexanone (oxime), caprolactam [19, 20]... 

About 90% of the caprolactam is produced by the conventional cyclohexanone process. Cyclohexanone is obtained by catalytic oxidation of cyclohexane with air, or by hydrogenation of phenol and dehydrogenation of the cyclohexanol byproduct. The conversion of cyclohexanone to cyclohexanone oxime followed by Beckmann rearrangement gives caprolactam. About 10% of caprolactam is produced by photonitrosation of cyclohexane or by nitrosation of cyclohexanecarboxylic acid in the presence of sulfuric acid264. 

High initial conversions of cyclohexanone oxime (I) were observed with HY at 380-390° (Table XXIX). The major product was caprolactam (II), together with moderate amounts of 5-cyanopentene-l (III) and small amounts of cyclohexanone and cyclohexanol. The ketone arose from hydrolysis of the oxime, and the alcohol was produced by an... 

Caprolactam (world production of which is about 5 million tons) is mostly produced from benzene through three intermediates cyclohexane, cyclohexanone and cyclohexanone oxime. Cyclohexanone is mainly produced by oxidation of cyclohexane with air, but a small part of it is obtained by hydrogenation of phenol. It can be also produced through selective hydrogenation of benzene to cyclohexene, subsequent hydration of cyclohexene and dehydrogenation of cyclohexanol. The route via cyclohexene has been commercialized by the Asahi Chemical Company in Japan for adipic acid manufacturing, but the process has not yet been applied for caprolactam production. 

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. 

Cyclohexanone, a six-membered carbon ring with a ketone as functional group, is almost exclusively applied as a precursor for the production of aliphatic polyamides. Pure cyclohexanone is mainly converted, via cyclohexanone oxime and caprolactam, to nylon-6 (also called polycaprolactam) [1]. Mixtures of cyclohexanone and cyclohexanol, often called K4 oil, are converted via oxidation into adipic acid that reacts with hexamethylene diamine (HMDA) to nylon-6,6 (poly-hexamethylene adipamide). Other applications of these products can be found in the field of polyurethane and polyester production. 

Cyclohexanone oxime dissolved in ca. 2 M NaOH containing NaBH4, and refluxed 2 hrs. cyclohexanol. Y 87%. - Similarly via the Na-salt of the boric acid diester a-Hydroximinoacetophenone l-phenylethane-l,2-diol. Y 72-78%. -Oximes of conjugated carbonyl compds., such as cinnamaldehyde or acetophenone, do not react. F. e. s. K. H. Bell, Australian J. Chem. 23, 1415 (1970). 

Cyclohexanone alone is the main starting point for the newer nylon-6 the hydrogenation of phenol can be directed to give this material, but KA oil (or cyclohexanol) must be dehydrogenated. The sulphate or, more recently, phosphate of the oxime, formed by reaction with hydroxylamine (as its salt), undergoes the Beckmann rearrangement in the presence of oleum. (Excess acid is neutralized with ammonia for sale into fertilizers.)... 

The oxime is also accessible through the liquid-phase ammonoxidation of cyclohexanol phosphotungstic acid, H3PWi2O40 (8-12)H2O, is a very effective catalyst ... 

The most important products of cyclohexane are the polyamide building blocks, adipic acid and caprolactam, which are obtained by oxidation of cyclohexanol or by the formation of the oxime from cyclohexanone and subsequent Beckmann rearrangement. 

Nylon 6 is produced from caprolactam. Phenol is hydrogenated to cyclo-hexanol. This cyclohexanol is dehydrogenated to cyclohexanone, which is then converted to its oxime. Beckmann rearrangement of the oxime gives caprolactam, which is largely converted to a linear polymer on heating underpressure (Eqs. 30-31)-... 

The first step consists of the air oxidation of cyclohexane to a mixture of cyclohexanol and cyclohexanone as described in Section 9.2.2.1. The mixture is fractionated by distillation and the cyclohexanol is dehydrogenated to cyclohexanone over a catalyst such as copper. The combined cyclohexanone fractions are then treated with aqueous hydroxylamine sulphate at 20—95°C to form the oxime. The reaction mixture is neutralized with aqueous ammonia or sodium hydroxide and the crude oxime separated as an oily layer. This is stirred with concentrated sulphuric acid at 120 C and the oxime undergoes the Beckmann rearrangement to give caprolactam. In one process, the solution containing the lactam is continuously withdrawn from the reactor and rapidly cooled to below 75°C to minimize hydrolysis. The solution is then further cooled and neutralized with aqueous ammonia. Crude caprolactam separates as an oil and is purified by distillation under reduced pressure. 

Cyclohexanelhiol Cyclohexanol Cyclohexanone Cyclohexanone oxime Cyclohexanone peroxide Cydohexene 1-Cydohexenecarbonilrile 1-Cyclohexene-1-carboxaldehyde 3-Cydohexene-1-carboxaldehyde... 

Reduction of oximes (133) either with sodium in ethanol or with LiAlH gave only the equatorial amine in greater than 90% yield, whereas corresponding reductions of the parent ketones gave a mixture of the epimeric cyclohexanols in which the equatorial alcohol (59—80%) was the major component. In view of the similarity of the keto- and oximino-groups it was... 

The attempt to synthesize pyrroles via prototropic isomerization of O-allyl ketoximes to 0-(0-l-propenyl) ketoximes, followed by their [3,3]-sigmat-ropic rearrangement, failed [316,317]. Instead, in the case of O-allyl cyclohexanone oxime (KOH/DMSO or Bu OK/DMSO, 50°C-140 C, 1-6 h), a mixture of 2-methylene-l-cyclohexanol, 5,6,7,8-tetrahydroquinoline, and cyclohexanone in... 

SCHEME 1.160 Formation of 1-ethynyl-l-cyclohexanol in the reaction of cyclohexanone oxime and acetylene in superbase media. 

The preparation of s-caprolactam via the Beckman rearrangement of cyclohexanone oxime was first described by Wallach in 1900. In the I.G. Faiben process, phenol was hydrogenated to cyclohexanol, at 140°-160°C and 15 bar, with a nickel oxide/silica catalyst. The cyclohexanol was del drogenated to cyclohexanone using a zinc/iron catalyst at 400°C, and the cyclohexanone oxime was formed by reaction with hydroxylamine monosidfonate. Conversion to cyclohexanone oxime was maximized at pH 7 by neutralizing the solution with ammonia. The organic layer of cmde oxime was crystallized and then isomerized to s-caprolactam with 20% oleum at 120°C. e-Caprolactam was purified and the ammonium sulfate recovered. 

---