Caprolactam From cyclohexane

This proces uses the same steps as the conventional process for manufacturing caprolactam from cyclohexane oxidation, oximation of cydododecanone, Beckmann rearrangement... 

Ishii and co-workers reported the N-hydroxyphthalimide (NHIP)-catalyzed nitro-sation of cyclohexane with te.it-butyl nitrite ( BuONO) to give nitrosocyclohexane in high yield (Equation 10.5) [11]. Subsequently, they reported an efficient one-pot procedure for the preparation of e-caprolactam from cyclohexane by means of cyanuric acid chloride [12]. The present route towards e-caprolactam obviates the use of corrosive NOC1 in the photonitrosation of cyclohexane. 

Butadiene is trimerized with a Ziegler-Natta catalyst to give 1,5,9-cyclo-dodecatriene which is then hydrogenated to cyclododecane. Dodecyl lactam is then obtained by a series of reactions similar to those used to prepare caprolactam from cyclohexane (Section 9.2.2.5). 

BASF s strongest product presence is nylon 6, in which it is highly integrated. The company makes caprolactam from cyclohexane and then nylon 6 polymer, at its integrated sites in Ludwigshafen, Germany, and Freeport, Texas. The polymer is next finished and fhen eifher compounded or sold direcfly to processors, independent compounders, and fiber producers. At one time, BASF made its own nylon 6 fibers, buf exited that business via a portfolio swap with Allied-Honey well in 2003, that sent the fibers business to Allied-Honeywell and the engineering plastics business to BASF. 

AH commercial processes for the manufacture of caprolactam ate based on either toluene or benzene, each of which occurs in refinery BTX-extract streams (see BTX processing). Alkylation of benzene with propylene yields cumene (qv), which is a source of phenol and acetone ca 10% of U.S. phenol is converted to caprolactam. Purified benzene can be hydrogenated over platinum catalyst to cyclohexane nearly aH of the latter is used in the manufacture of nylon-6 and nylon-6,6 chemical intermediates. A block diagram of the five main process routes to caprolactam from basic taw materials, eg, hydrogen (which is usuaHy prepared from natural gas) and sulfur, is given in Eigute 2. 

The first step in producing caprolactam from benzoic acid is its hydrogenation to cyclohexane carboxylic acid at approximately 170°C and 16 atmospheres over a palladium catalyst ... 

About half of the nylon made in the world is made from the polymerization of caprolactam. Although the cyclohexanone needed to make caprolactam can be made from cyclohexane as shown above, most of it is made from phenol. 

PNC [Photonitrosation of cyclohexane] A photochemical process for making caprolactam (a precursor for nylon) from cyclohexane, nitrosyl chloride, and hydrogen chloride. The first photochemical product is cyclohexanone oxime ... 

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. 

About Half the caprolactam is made from phenol. (The other half comes from cyclohexane.) Caprolactam is an intermediate step in making Nylon 6. 

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, adipic acid, and hexamethylenediamine (HMDA) are all made from cyclohexane. Almost all high-purity cyclohexane is obtained by hydrogenating benzene, although some for solvent use is obtained by careful distillation of selected petroleum fractions. 

Caprolactam. Essentially all caprolactam is used in the manufacture of nylon 6 fibers. In 1998, global demand reached nearly 7.3 billion lb with 1.7 billion lb used in North America. This is a fast-growing nylon with applications in carpets, textiles, and tires. Caprolactam can be produced from cyclohexane, phenol, and toluene via cyclohexanone. It is then reacted with hydroxylamine to give an oxime. The oxime undergoes an acid-catalyzed rearrangement to give caprolactam. 

Adipic acid (48th in volume), for example, is almost entirely derived from cyclohexane (47th) as is much of the production of caprolactam and hexam-ethylenediamine (1,6-diaminohexane). The production sequences to all of these products will be outlined. 

Processes for producing caprolactam from phenol and cyclohexane... 

Figure 1 illustrates the principal raw materials and intermediates for both nylon 6 and nylon 6/6. Two of the three intermediates, caprolactam and adipic acid, are derived from cyclohexane. 

Benzoyl peroxide (BPO) was dried on phosphorous pentoxide under vacuum. Commercial e-caprolactam (CL) was dried on phosphorous pentoxide and twice recrystallized from cyclohexane. Xylene was dried by refluxing over sodium metal. Maleic anhydride (MAH) and EPM... 

E-Caprolactam is recrystallized twice from cyclohexane and dried in vacuum at room temperature over P4O10 for 48 h mp 68-69°C. 

The major commercial route to caprolactam is from cyclohexane (Section 9.2.2.1) as follows ... 

About 60% of cyclohexane production is used to make adipic acid and hexamethyl-ene diamine for nylon-6,6 production, as well as the caprolactam for nylon-6 production. About 70% of all caprolactam is produced from cyclohexane (mainly used to synthesize nylon-6). 

Although most of the cyclohexanone used to produce adipic acid and e-caprolactam has been made from cyclohexane it is also possible for phenol to be used. The original I. G. Farben process using phenol operated in two stages ... 

C, b.p. 81"C. Manufactured by the reduction of benzene with hydrogen in the presence of a nickel catalyst and recovered from natural gase.s. It is inflammable. Used as an intermediate in the preparation of nylon [6] and [66] via caprolactam and as a solvent for oils, fats and waxes, and also as a paint remover. For stereochemistry of cyclohexane see conformation. U.S. production 1980 1 megatonne. 

Since adipic acid has been produced in commercial quantities for almost 50 years, it is not surprising that many variations and improvements have been made to the basic cyclohexane process. In general, however, the commercially important processes stiU employ two major reaction stages. The first reaction stage is the production of the intermediates cyclohexanone [108-94-1] and cyclohexanol [108-93-0], usuaHy abbreviated as KA, KA oil, ol-one, or anone-anol. The KA (ketone, alcohol), after separation from unreacted cyclohexane (which is recycled) and reaction by-products, is then converted to adipic acid by oxidation with nitric acid. An important alternative to this use of KA is its use as an intermediate in the manufacture of caprolactam, the monomer for production of nylon-6 [25038-54-4]. The latter use of KA predominates by a substantial margin on a worldwide basis, but not in the United States. 

Enzymatic hydrolysis is also used for the preparation of L-amino acids. Racemic D- and L-amino acids and their acyl-derivatives obtained chemically can be resolved enzymatically to yield their natural L-forms. Aminoacylases such as that from Pispergillus OTj e specifically hydrolyze L-enantiomers of acyl-DL-amino acids. The resulting L-amino acid can be separated readily from the unchanged acyl-D form which is racemized and subjected to further hydrolysis. Several L-amino acids, eg, methionine [63-68-3], phenylalanine [63-91-2], tryptophan [73-22-3], and valine [72-18-4] have been manufactured by this process in Japan and production costs have been reduced by 40% through the appHcation of immobilized cell technology (75). Cyclohexane chloride, which is a by-product in nylon manufacture, is chemically converted to DL-amino-S-caprolactam [105-60-2] (23) which is resolved and/or racemized to (24)... 

Caprolactam [105-60-2] (2-oxohexamethyleiiiiriiQe, liexaliydro-2J -a2epin-2-one) is one of the most widely used chemical intermediates. However, almost all of the aimual production of 3.0 x 10 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 Cyclohexanoland cyclohexanone). Reaction with ammonia-derived hydroxjlamine forms cyclohexanone oxime, which undergoes molecular rearrangement to the seven-membered ring S-caprolactam. 

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 major aromatics (organics having at least one ring structure with six carbon atoms) manufactured include benzene, toluene, xylene, and naphthalene. Other aromatics manufactured include phenol, chlorobenzene, styrene, phthalic and maleic anhydride, nitrobenzene, and aniline. Benzene is generally recovered from cracker streams at petrochemical plants and is used for the manufacture of phenol, styrene, aniline, nitrobenzene, sulfonated detergents, pesticides such as hexachlorobenzene, cyclohexane (an important intermediate in synthetic fiber manufacture), and caprolactam, used in the manufacture of nylon. Benzene is also used as a general purpose solvent. 

KA oil is used to produce caprolactam, the monomer for nylon 6. Caprolactam is also produced from toluene through the intermediate formation of cyclohexane carboxylic acid. 

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