Nitrocyclohexane process

With the advent of petrochemistry, BASF gradually replaced phenol by cyclohexane as the starting material. Development of a new continuous caprolactam process based on cyclohexane was started by BASF in 1950, and a full-scale plant went on stream in 1960 [20]. Similar processes based on cyclohexane were developed by DSM, Bayer and Inventa. A number of alternative processes were developed by other companies (Fig. 3). To name only some of them the cumene/phenol based process of Allied (on stream in 1958), the photonitrosation process of Toyo Rayon (1962), the toluene based Snia process (1964), and DuPont s nitrocyclohexane process (in operation from 1961 to 1966). 

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 This process has been superseded by other, more efficient processes (see Caprolactam).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. 

Nixan [Nitrocyclohexane] A process for making cyclohexane oxime (an intermediate in the manufacture of nylon) from benzene by liquid phase nitration, followed by hydrogenation of the nitrobenzene. Invented by Du Pont and operated from 1963 to 1967. 

Nitroalkanes. A process was developed and operated for a time for the manufacture of s-caprolactam based on the nitration of cyclohexane.197 Nitrocyclohexane thus prepared was transformed to e-caprolactam via cyclohexanone oxime. At present the only industrial process to produce nitroalkanes by direct nitration is the manufacture of nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane. 

The above mentioned process of the transformation of compounds should also be possible for the other nitro compounds studied, nitromethane and nitrocyclohexane. However, no aliphatic nitroso compounds (or oximes obtained by isomerisation of the aliphatic nitroso compound) have been detected either in the gas or in the adsorbed phase. This is obviously caused by the easy migration of the a-hydrogen along... 

The catalytic oxidation of cyclohexane is performed in the liquid phase with air as reactant and in the presence of a catalyst. The resulting product is a mixture of alcohol and ketone (Table 1, entry 12) [19]. To limit formation of side-products (adipic, glutaric, and succinic acids) conversion is limited to 10-12 %. In a process developed by To ray a gas mixture containing HC1 and nitrosyl chloride is reacted with cyclohexane, with initiation by light, forming the oxime directly (Table 1, entry 12). The corrosiveness of the nitrosyl chloride causes massive problems, however [20]. The nitration of alkanes (Table 1, entry 13) became important in a liquid-phase reaction producing nitrocyclohexane which was further catalytically hydrated forming the oxime. 

Nitrocyclohexane has been prepared by E. I. du Pont de Nemours Company by nitration of cyclohexane. Cyclohexane undergoes nitration and oxidation to give nitrocyclohexane and adipic acid along with smaller amounts of glutaric acid and succinic add. Nitration is accelerated by the addition of nitrogen dioxide. The process may be operated continuously in the liquid phase with 45-75 per cent nitric acid at temperatures of 100-200 C and pressures of 2-10 atm. This process is of particular interest in that oxidation products from cycloalkanes are usually S3rmmetrical di-carboxylic acids, which are of industrial importance. 

Nitrogen Compounds. The aqueous Oxone-acetone combination has been developed for the transformation of certain anilines to the corresponding nitrobenzene derivatives, as exemplified in eq 15. This process involves sequential oxidation steps proceeding by way of an intermediate nitroso compound. In the case of primary aliphatic amines, other reactions of the nitrosoalkane species compete with the second oxidation step (for example, dimerization and tautomerization to the isomeric oxime), thereby limiting the synthetic generality of these oxidations. An overwhelming excess of aqueous Oxone has been used to convert cyclohexylamine to nitrocyclohexane (eq 16)P... 

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. 

The vapor-phase nitration of cyclohexane with N O2 at 240 ° C forms nitrocyclohexane in only 16% yield together with large amounts of rmdesired nitrated products Lee, R. and Albright, E.L. (1965) Ind. Eng. Chem. Process Res. Dev., 4, 411. 

The reactions of halide and azide ions (see above), cyanide ion (see Chap. 7) and thiocyanate ions (see Sect. 13.7) have all been discussed. In the general context of halides and pseudohalides, it should be noted that nitrite ion has been successfully phase-transferred [31, 32]. The yields for the formation of nitroalkanes in either crown [31 ] or quaternary ion catalyzed [32] processes are fair to good for primary alkanes and poor for secondary systems. Bromocyclohexane, for example, afforded only traces of nitrocyclohexane when treated with nitrite ion, the by-products resulting presumably from oxygen attack (nitrite ester formation) or elimination. The conversion of n-octy bromide into the corresponding nitro-compound is formulated in equation 9.14 and several examples of the transformation are recorded in Table 9.6. 

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