Cyclohexanone conversion

Catalyst Ti H202/cyclohexanone Conversion Oxime selectivity Oxime yield... 

Fe(III), Ce(IV), Ru(II) and monomeric V species (e.g., [V0 0-i-Pr 3]) also lead to cyclohexanone conversions that are as good as the heteropoly-compounds in this class of reactions, but with lower selectivity to the diacids. However, better performance is obtained when the reaction is catalyzed by Cu(N03)2 [131]. At 110 ° C and 8 h reaction time, 95% cyclohexanone conversion with 72% yield to AA, 8% to glutaric and 10% to succinic acid were obtained in an acetic acid-water solvent. A similar performance was reported with Mn(OAc)2 in acetic acid-CFsCOOH solvent, at 65 °C after a 3-h reaction time 99.8% conversion, 75% yield of AA, 9% to glutaric acid and 1% to succinic acid [14jj. 

The influence of the metal content on the initial activity (Ao) for cyclohexanone transformation is shown in Figure 2 for the PtHFAU and PdHFAU catalysts. For both series of catalysts, Ao first increases with the metal content reaching a constant value for percentages of platinum or palladium equal to or greater than 0.2 wt%. This shape of curve is that expected from a bifunctional mechanism [7]. At low metal contents the cyclohexanone conversion is limited by hydrogenation steps hence the activity increases with the metal content. For metal contents > 0.2 wt% the cyclohexanone conversion is limited by the acid steps hence the activity depends no more on the metal content. 

Flow reactor. Feed 1 1 cyclohexanol and cyclohexanone. Conversion of cyclohexanol 30-60%. Adapted after Refs. 56, 57. 

Six-membered Rings.—Cyclohexanones. Conversion of an alicyclic ketone into its corresponding methylene derivative is often necessary, but existing methods tend to require vigorous conditions. A mild method has been reported in which the ketone tosylhydrazone is treated with catechol borane in chloroform at 263 K and the reduction product decomposed with sodium acetate. Yields of 40—90% are claimed. 

Cyclohexane. The LPO of cyclohexane [110-82-7] suppUes much of the raw materials needed for nylon-6 and nylon-6,6 production. Cyclohexanol (A) and cyclohexanone (K) maybe produced selectively by using alow conversion process with multiple stages (228—232). The reasons for low conversion and multiple stages (an approach to plug-flow operation) are apparent from Eigure 2. Several catalysts have been reported. The selectivity to A as well as the overall process efficiency can be improved by using boric acid (2,232,233). K/A mixtures are usually oxidized by nitric acid in a second step to adipic acid (233) (see Cyclohexanol and cyclohexanone). 

Allied-Signal Process. Cyclohexanone [108-94-1] is produced in 98% yield at 95% conversion by liquid-phase catal57tic hydrogenation of phenol. Hydroxylamine sulfate is produced in aqueous solution by the conventional Raschig process, wherein NO from the catalytic air oxidation of ammonia is absorbed in ammonium carbonate solution as ammonium nitrite (eq. 1). The latter is reduced with sulfur dioxide to hydroxylamine disulfonate (eq. 2), which is hydrolyzed to acidic hydroxylamine sulfate solution (eq. 3). 

BASF. In the Badische process, cyclohexanone is produced by Hquid-phase catalytic air oxidation of cyclohexane to KA oil, which is a mixture of cyclohexanone and cyclohexanol, and is followed by vapor-phase catalytic dehydrogenation of the cyclohexanol in the mixture. Overall yields range from 75% at 10% cyclohexane conversion to 80% at 5% cyclohexane conversion. 

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... 

Toray. The photonitrosation of cyclohexane or PNC process results in the direct conversion of cyclohexane to cyclohexanone oxime hydrochloride by reaction with nitrosyl chloride in the presence of uv light (15) (see Photochemical technology). Beckmann rearrangement of the cyclohexanone oxime hydrochloride in oleum results in the evolution of HCl, which is recycled to form NOCl by reaction with nitrosylsulfuric acid. The latter is produced by conventional absorption of NO from ammonia oxidation in oleum. Neutralization of the rearrangement mass with ammonia yields 1.7 kg ammonium sulfate per kilogram of caprolactam. Purification is by vacuum distillation. The novel chemistry is as follows ... 

The oxidation of cyclohexane to a mixture of cyclohexanol and cyclohexanone, known as KA-od (ketone—alcohol, cyclohexanone—cyclohexanol cmde mixture), is used for most production (1). The earlier technology that used an oxidation catalyst such as cobalt naphthenate at 180—250°C at low conversions (2) has been improved. Cyclohexanol can be obtained through a boric acid-catalyzed cyclohexane oxidation at 140—180°C with up to 10% conversion (3). Unreacted cyclohexane is recycled and the product mixture is separated by vacuum distillation. The hydrogenation of phenol to a mixture of cyclohexanol and cyclohexanone is usually carried out at elevated temperatures and pressure ia either the Hquid (4) or ia the vapor phase (5) catalyzed by nickel. 

G-20 Dicarboxylic Acids. These acids have been prepared from cyclohexanone via conversion to cyclohexanone peroxide foUowed by decomposition by ferrous ions in the presence of butadiene (84—87). Okamura Oil Mill (Japan) produces a series of commercial acids based on a modification of this reaction. For example, Okamura s modifications of the reaction results in the foUowing composition of the reaction product C-16 (Linear) 4—9%, C-16 (branched) 2—4%, C-20 (linear) 35—52%, and C-20 (branched) 30—40%. Unsaturated methyl esters are first formed that are hydrogenated and then hydrolyzed to obtain the mixed acids. Relatively pure fractions of C-16 and C-20, both linear and branched, are obtained after... 

Clean examples of diaziridine to hydrazone rearrangements are rare. Diaziridine (119) mentioned above rearranges to the isomeric enhydrazone in boiling toluene, and 2,4-dinitrophenyldiaziridine (125) under the same conditions affords the 2,4-dinitrophenylhy-drazone (145) within 4 h. On blocking this rearrangement by iV-methyl, conversion with loss of cyclohexanone occurred to give benzotriazole iV-oxide (146) (72JOC2980). 

The conversion of cyclohexanone to cyclohexanone oxime is brought about by the use of hydroxylamine sulphate. The sulphuric acid is neutralised with ammonia to ammonium sulphate and this is separated from the oxime. In the presence of oleum the oxime undergoes the process known as the Beckmann rearrangement to yield the crude caprolactam. After further neutralisation with ammonia the caprolactam and further ammonium sulphate are separated by solvent extraction (Figure 18.7). 

A route to phenol has been developed starting from cyclohexane, which is first oxidised to a mixture of cyclohexanol and cyclohexanone. In one process the oxidation is carried out in the liquid phase using cobalt naphthenate as catalyst. The cyclohexanone present may be converted to cyclohexanol, in this case the desired intermediate, by catalytic hydrogenation. The cyclohexanol is converted to phenol by a catalytic process using selenium or with palladium on charcoal. The hydrogen produced in this process may be used in the conversion of cyclohexanone to cyclohexanol. It also may be used in the conversion of benzene to cyclohexane in processes where benzene is used as the precursor of the cyclohexane. 

Bromocyclohept-2-en-l-one (40) should be convertable to cycloheptenone (41) by hydrogenolysis of the bromine atom. Thus the process (34) - (41) provides a general method for conversion of symmetrical cyclohexanones to cycloheptenones. 

The formation of bicyclic imines (263,264) from piperidine enamines and y-bromopropyl amines may appear at first sight to be a simple extension of the reactions of enamines with alkyl halides. However, evidence has been found that the products are formed by an initial enamine exchange, followed by an intramolecular enamine alkylation. Thus y-bromodiethylamino-propane does not react with piperidinocyclohexene under conditions suitable for the corresponding primary amine. Furthermore, the enamine of cyclopentanone, but not that of cyclohexanone, requires a secondary rather than primary y-bromopropylamine, presumably because of the less favorable imine to enamine conversion in this instance. 

A synthesis of an indolo[3,2-fl]carbazole (2) was reported in 1951—the first preparation of a compound belonging to this class (Scheme 13). This was accomplished commencing with cyclohexanone, via conversion to the bishydrazone 108, which underwent Fischer indolization in glacial acetic acid to furnish the octahy-dro derivative 109. After a final dehydrogenation step, the desired product 2 was obtained (51JCS809). 

This ether formation arises from conversion of the phenol to a cyclohexanone, and ketal formation catalyzed by Pd-Hj and hydrogenolysis. With Ru-on-C, the alcohol is formed solely (84). 

Because of the industrial magnitude of these processes, many catalysts have been examined with variations in metal distribution, pore size, and alkalinity. In most synthetic work where catalyst life and small variations in yield are not of great importance, most palladium-on-carbon or -on-alumina powder catalysts will be found satisfactory for conversion of phenols to cyclohexanones. Palladium has a relatively low tendency to reduce aliphatic ketones, and a sharp decrease in the rate of absorption occurs at about 2 mol of consumed hydrogen. Nickel may also be used but overhydrogenation is more apt to occur. 

A Comparison of the Degrees of Conversion to Cyclohexanol (xi) in the Hydrogenation of Phenol and of Cyclohexanone, respectively ... 

The direct conversion of 3-methylcyclohex-2-enone into 2-allyl-3-methylcyclohexanone provides an interesting example of the utility of the reduction-alkylation procedure. Synthesis of this compound from 3-methy I cyclohexanone would be difficult because the latter is converted mainly into 2-alkyl-5-methylcyelohexanones either by direct base-catalyzed alkylation11 or by indirect methods such as alkylation of its enamine (see Note 13) or alkylation of the magnesium salt derived from its cyclohexylimine.12... 

This is the only convenient way to make these compounds, since elimination by any other route gives the thermodynamically more stable a,P-unsaturated isomers. This is an illustration of the utility of the Wittig method for the specific location of a double bond. Another illustration is the conversion of cyclohexanones to alkenes containing exocyclic double bonds, for example, ... 

Conversion of sulfones such as 1955 into their a-sulfonyl anions by treatment with n-BuIi at -78°C in THF then addition of bis(trimethylsilyl)peroxide (BTSP) 1949 afford, via intermediates such as 1956, aldehydes or ketones such as cyclohexanone and HMDSO 7 [146]. This reaction has subsequently been applied to the synthesis of aldehydes [147]. After hthiation with -BuLi thioethers such as phenyl benzyl sulfide 1957 react with BTSP 1949 to give mixtures of the O-silyl 1958 and C-silyl 1959 products [148]. On treatment with -BuLi at -30°C the a,a-bis-(trimethylsilyl)dimethylsulfide 1960 is, hkewise, converted into its anion, which reacts with 1949 to give the a-trimethylsilyloxy sulfide 1961 and MesSiOLi 98 [149] (Scheme 12.41). 

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