Cyclohexanone caprolactam from

Perhaps the most notable application of the Beckmann rearrangement is in the industrial production of 8-caprolactam from cyclohexanone (or its oxime), which is used as monomer for the polymerization to a polyamide for the production of synthetic fibres (for example, nylon 6). Furthermore, Beckmann rearrangement provides a facile route for the... 

Some most important solvent-free routes for selective oxidations of hydrocarbons and aromatics [9], hydrogenations [10], and for a one step production of e-caprolactam from cyclohexanone with a mixture of air and ammonia using porous heterogeneous catalysts have been reported, in which the active sites have been atomically engineered [11]. There are also reactions in which at least one reactant is liquid under the conditions employed, which means the solvent normally used can simply be left out. To begin with, two industrially important examples are discussed, which confirm that a reaction process that is more environmentally friendly can also be economically very acceptable. This is followed by some recent examples of solvent-free reactions covering a remarkably broad range of reaction types in which the term solvent-free refers solely to the reaction itself. On the other hand, workup processes, except for a few examples, invariably involve the use of solvent. The... 

The conversion of oximes into amides or lactams (reactions 6 or 7), in particular, e-caprolactam from cyclohexanone oxime (X = H), is catalyzed by [NBu4][Re04] andCFsSOsH in refluxing nitromethane, via a postulated perrhenic ester of oxime [RR C=N-0-Re03]. ... 

This reactor was tested for the production of E-caprolactam from cyclohexanone-oxime (Fig. 9). 

Table 3 Production of s-caprolactam from cyclohexanone-oxime via various techniques...

Figure 1Z12 shows a conventional industrial flow sheet for the manufacture of crude caprolactam from cyclohexanone. 

Allied Chemical recently proposed a simplified technique, producing caprolactam from cyclohexanone, ammonia and oxygen in a single step, in the vapor phase, on a sffica or alumina-based catalyst However, the drawback of this process resides in the fact that only half of the oxime is converted in situ to caprolactam. This makes it necessary to resort to the Beckmann rearrangement For a 50 per cent conversion of cyclohexanone, the molar selectivity of oxime and caprolactam is 68 per cent Although this method considerably reduces the production of ammonium sulfate, the yields are still too low for it to appear to be more economical than the foregoing routes. 

Until 2005, DSM produced about 130 kt/a of phenol, used as a raw material to produce caprolactam from cyclohexanone. Phenol was produced by a copper-catalysed oxidation of benzoic acid. The raw material, benzoic acid, was produced in the same plant by the cobalt-catalysed oxidation of toluene, which also produced significant amounts of benzaldehyde (Fig. 16.19). 

Ingredients. Nylon-6 is produced commercially from caprolactam [105-60-2] which is the most important lactam industrially. AH industrial production processes for caprolactam are multistep and produce ammonium sulfate [7783-20-2] or other by-products. Approximately 95% of the world s caprolactam is produced from cyclohexanone oxime [100-64-1] via the Beckmann rearrangement (144). The starting material for cyclohexanone can be... 

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... 

Currently, cyclohexanone oxime is synthesized starting from cyclohexanone and hy-droxylamine (Route A, Scheme 30) or by photonitrosation of cyclohexane with NOCl (PNC process. Route B, Scheme 30). Of these approaches. Route A is most often employed and accounts for about 70% of the total production of e-caprolactam worldwide. However, this method has several drawbacks. ... 

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 processes are used for the industrial production of caprolactam. Generally cyclohexanone is the key intermediate and it is produced by catalytic hydrogenation of phenol (ex benzene or toluene) or the catalytic autoxidation of cyclohexane (from benzene hydrogenation) as shown in Fig. 2.27. 

For some years Foray s enzymatic process for L-lysine (L-Lys, 41) was competitive compared with fermentation. This chemoenzymatic L-Lys production was established with a capacity of 5000-10000 t/y. The key intermediate is a-amino-e-caprolactam (ACL), produced from cyclohexanone in a modified Beckmann rearrangement. The enantiospecific hydrolysis forming L-Lys is based on two enzymes L-ACL-hydrolase opens the ring of ACL to L-Lys and in the presence of the ACL-racemase the d-ACL is racemized. Incubating d,l-ACL with cells of Cryptococcus laurentii having l-ACL lactamase activity together with cells of Achromobacter obae with ACL-racemase activity, L-Lys could be obtained in a yield of nearly 100% (Scheme 24) [102]. 

The second TS-1 based process which is likely to go into commercial production is the synthesis of cyclohexanone oxime from cyclohexanone, ammonia, and hydrogen peroxide (Roiiia et al., 1990) (reaction 6.13), which is the first step in the preparation of e-caprolactam (Montedipe, pilot plant). Oxime selectivity is >98% at a conversion of 99.9%. 

The Techni-Chem. process (process 10, Figure 2.11) that started from cyclohexanone also did not develop beyond pilot plant operations [127]. It is characterized by the following reaction scheme entailing (1) acylation of cyclohexanone with ketene, (2) nitration of the resulting cyclohexenyl acetate with concurrent deacetylation to 2-nitrocyclohexanone, (3) hydrolytic cleavage to s-nitrocaproic acid, (4) hydrogenation to s-aminocaproic acid, and (5) cyclization to caprolactam ... 

A one-pot synthesis of s-caprolactam over bifunctional MeAPOs has also been demonstrated in which a Mg,Mn(III)APO-5 is able to catalyse the synthesis of s-caprolactam (Scheme 9.15) from cyclohexanone in the presence of air and ammonia alone. The transition metal is responsible for generation of hydroxylamine and the mild acidity associated with the metals in the alumino-phosphate framework is sufficient to catalyse the Beckmann rearrangement. ... 

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. 

Caprolactam, the monomer from which nylon 6 is synthesized, is prepared from cyclohexanone in two steps. In Step 1, cyclohexanone is treated with hydroxylamine to form cyclohexanone oxime. Treatment of the oxime with concentrated sulfuric acid in Step 2 gives caprolactam by a reaction called a Beckmann rearrangement. Propose a mechanism for the conversion of cyclohexanone oxime to caprolactam. 

An integrated process, which combines catalytic EniChem TS-1, catalyzed direct ammoximation of cyclohexanone and Sumitomo Chemical vapour-phase Beckmann rearrangement, both exploiting MFI based zeolite-like materials, is now industrially used for greener caprolactam production from cyclohexanone without co-producing any ammonium sulfate (Fig. 15.2). ... 

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