Caprolactam, preparation

Sodium caprolactamate (prepared in situ from sodium metal and CL) and N-acetyl caprolactam were chosen as initiator and activator, respectively. The starting temperature of polymerization was 155°C. A double-walled glass reactor, of about 60 cm, equipped with mechanical stirrer, inert gas inlet and outlet and thermocouple lodging was used (3 ). The polymerization products were fractionated following the published literature (b) into high polymer, residual monomer, higher oligomers and low molecular mass side products, and their respective yields were determined. Monomer content has also been evaluated by g.l. c. 

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. 

Uses. The principal use of adiponitrile is for hydrogenation to hexamethylene diamine leading to nylon-6,6. However, as a result of BASE s new adiponitrile-to-caprolactam process, a significant fraction of ADN produced may find its way into nylon-6 production. Adipoquanamine, which is prepared by the reaction of adiponitrile with dicyandiamide [461-58-5] (cyanoguanidine), may have uses in melamine—urea amino resins (qv) (see "Benzonitrile, Uses"). Its typical Hquid nitrile properties suggest its use as an extractant for aromatic hydrocarbons. 

Developments in aliphatic isocyanates include the synthesis of polymeric aliphatic isocyanates and masked or blocked diisocyanates for appflcafions in which volatility or reactivity ate of concern. Polymeric aliphatic isocyanates ate made by copolymerizing methacrylic acid derivatives, such as 2-isocyanatoethyl methacrylate, and styrene [100-42-5] (100). Blocked isocyanates ate prepared via the reaction of the isocyanate with an active hydrogen compound, such as S-caprolactam, phenol [108-95-2] or acetone oxime. 

Ketones are an important class of industrial chemicals that have found widespread use as solvents and chemical intermediates. Acetone (qv) is the simplest and most important ketone and finds ubiquitous use as a solvent. Higher members of the aUphatic methyl ketone series (eg, methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone) are also industrially significant solvents. Cyclohexanone is the most important cycHc ketone and is primarily used in the manufacture of y-caprolactam for nylon-6 (see Cyclohexanoland cyclohexanone). Other ketones find appHcation in fields as diverse as fragrance formulation and metals extraction. Although the industrially important ketones are reviewed herein, the laboratory preparation of ketones is covered elsewhere (1). 

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)... 

Block, Gr ft, ndSta.r Copolymers. A host of copolymers of these types have been prepared. They iaclude block copolymers from S-caprolactam and PTMEG as well as block copolymers from PTHF and other cationicaHy polymerizable heterocycles, including... 

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 preparation of nylon resins from lactam precursors involves ring opening, which is facihtated by a controlled amount of water in the reaction mixture. The salt complex condenses internally to produce the polyamide (57). The synthesis of nylon-6 [25038-54-4] from S-caprolactam is as follows ... 

Commercial routes from acrylonitrile and from caprolactam have also been developed. This diamine may also be prepared from furfural and from butadiene. 

Caprolactam (industrial chemical used to prepare a type of nylon)... 

The step-growth polymer nylon 6 is prepared from caprolactam. The reaction involves initial reaction of caprolactam with water to give an intermediate open-chain amino acid, followed by heating to form the polymer. Propose mechanisms for both steps, and show the structure of nylon 6. 

Anionic copolymerization of e-caprolactam and cj-caprylolactam was also reported212,213. Organosiloxane copolymers can be prepared from two different cyclics by using acid or base catalysts214. ... 

On the other hand, nylon 6 is prepared from caprolactam, which behaves as a bifunctional monomer bearing two different functional groups, and hence the polymer is made up of just one type of unit along the backbone it is therefore a homopolymer. 

AlliedSignal s Infinity, Forever Renewable Nylon, prepared by recycling of polyamide-6, is briefly described. The polyamide is treated by depolymerisation, purification of the caprolactam monomer and repolymerisation. The new resin is said to exhibit the same properties as those of virgin polyamide-6. ALLIEDSIGNAL... 

The present invention is for a method of preparing purified epsilon-caprolaetam from earpet waste containing nylon-6. Contaminated epsilon-eaprolaetam is obtained by depolymerising nylon-6 from earpet waste. A mixture of the contaminated epsilon-eaprolaetam and water is then hydrogenated in the presenee of hydrogen and a hydrogenation catalyst in order to produce purified epsilon-caprolactam. The amount of contaminated epsilon-caprolactam in the mixture ean be between 10 and 95% by weight. 

One plant in the Nagoya (Japan) region alone is capable of producing 120 tons of caprolactam per day. In addition, the Nylon 12 monomer, lauryl lactam, is being prepared by a similar route from cyclododecane. 

Methoxyphenylurea, 31,10,13 Methyl -acetylbenzoate, 32, 81 Methyl acrylate, 30, 65 32, 86 y-Methylallophanate, 32, 62 Methylamine, 30, 60 4 -Methyl-2-aminobenzophenone, 32,12 N-Methylaniline, 30, 62 31,110 N-Methylarylamines, preparation by reductive alkylation, 30, 59, 60 Methylation, of e-caprolactam, 31, 72 of quinacetophenone, with dimethyl sulfate, 31, 91 with methyl iodide, 31, 90 2-Methyl-3,l,4-benzoxaz-4-one, 32, 12 N-Methyl-a-bromo-n-butyranilide, 30, 63... 

Zeolites have also been described as efficient catalysts for acylation,11 for the preparation of acetals,12 and proved to be useful for acetal hydrolysis13 or intramolecular lactonization of hydroxyalkanoic acids,14 to name a few examples of their application. A number of isomerizations and skeletal rearrangements promoted by these porous materials have also been reported. From these, we can underline two important industrial processes such as the isomerization of xylenes,2 and the Beckmann rearrangement of cyclohexanone oxime to e-caprolactam,15 which is an intermediate for polyamide manufacture. Other applications include the conversion of n-butane to isobutane,16 Fries rearrangement of phenyl esters,17 or the rearrangement of epoxides to carbonyl compounds.18... 

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