Nylon-6 production

C, b.p. 16UC. Manufactured by heating phenol with hydrogen under pressure in the presence of suitable catalysts. Oxidized to adipic acid (main use as intermediate for nylon production) dehydrogenated to cyclohexanone. 

In the petrochemical field, hydrogen is used to hydrogenate benzene to cyclohexane and benzoic acid to cyclohexane carboxylic acid. These compounds are precursors for nylon production (Chapter 10). It is also used to selectively hydrogenate acetylene from C4 olefin mixture. 

Rotary dryers Rolling mills, and most machining Nylon production lines... 

Sticking with nylon production, high-silica pentasil zeolites are used by Sumitomo to overcome environmental issues associated with the conversion of cyclohexanone oxime to caprolactam (Chapter 1, Scheme 1.4). 

Manufacturing dyes and pigments Core hardening of metals Nylon production Cyanogen chloride (CK) 1.25... 

Anonymous. National Historic Chemical Landmark The First Nylon Plant. American Chemical Society, 1995. Source for current nylon production. 

Mark H. Thiemens and William C. Trogler. Nylon Production An Unknown Source of Atmospheric Nitrous Oxide. Science. 251 (Feb. 22, 1991) 932-934. 

We can manipulate the properties of nylon products by changing the conditions under which we crystallize them. The degree of crystallinity is increased by slow cooling, annealing, and by crystallization from highly oriented melts. As we increase the crystallinity level, stiffness and yield strength increase at the expense of impact strength. 

They are shown in Figure 24-4. (Fibers made from nylon actually account for much more volume than resins made from nylon.) The two most popular nylons, both in resins and fibers, are Nylon 6 and 66. These two account for about 80% of the nylon production. 

Wallace Carothers and coworkers at DuPont synthesized aliphatic polyesters in the 1930s [Furukawa, 1998 Hounshell and Smith, 1988]. These had melting points below 100°C, which made them unsuitable for firber use. Carothers then turned successfully to polyamides, based on the theoretical consideration that amides melt higher than esters. Polyamides were the first synthetic fibers to be produced commercially. The polyester and polyamide research at DuPont had a major impact on all of polymer science. Carothers laid the foundation for much of our understanding of how to synthesize polymeric materials. Out of that work came other discoveries in the late 1930s, including neoprene, an elastomer produced from chloro-prene, and Teflon, produced from tetrafluoroethylene. The initial commercial application for nylon 6/6 was women s hosiery, but this was short-lived with the intrusion of World War II. The entire nylon 6/6 production was allocated to the war effort in applications for parachutes, tire cord, sewing thread, and rope. The civilian applications for nylon products burst forth and expanded rapidly after the war. 

Nylon finally became available to the general public in May 1940. Ten years had passed from initial discovery to full commercialization. It was a tremendous effort, even for a company with the resources of DuPont, and the R D cost was 4.3 million. During World War II, DuPont nylon production went up to 25 million pounds a year, and was used to make parachutes, airplane tire cords, and glider tow ropes. DuPont resumed selling nylon for stockings after the war. 

Caprolactam (C6HnNO) is also used to make nylon. Nylon-6 is made by direct polymerization of caprolactam, often obtained by reaction of cyclohexanone with hydroxylamine, followed by rearrangement of the oxime. Although nylon-6,6 is the dominant nylon produced in the United States, nylon-6 is the leading nylon product in Europe. 

Polymers Unsaturated fatty-acid chains offer opportunities for polymerisation that can be exploited to develop uses in surface coatings and plastics manufacturing. Polyunsaturated fatty acids can be dimerised to produce feedstocks for polyamide resin (nylon) production. Work is also ongoing to develop polyurethanes from vegetable oils through manipulation of functionality in the fatty-acid chains, to produce both rigid foams and elastomers with applications in seals, adhesives and moulded flexible parts (see Chapter 5 for more information). 

The rearrangement of cyclohexanone oxime to caprolactam is still an important step in nylon production, and the heterogeneously catalyzed Beckmann rearrangement has been extremely well investigated (4, 16-19). In order to obtain catalysts that couple a high lactam selectivity to long lifespan, careful tuning of the zeolite properties is required. Some important factors are ... 

One of the most smdied examples is the mimic of the enzyme cytochrome P-450 in the pores of a faujasite zeolite [196,204,225], The iron-phthalocyanine complex was encapsulated in the FAU supercage and is used as oxidation catalyst for the conversion of cyclohexane and cyclohexanone to adipic acid, an important intermediate in the nylon production. In this case the two step process using homogeneous catalysts could be replaced by a one step process using a heterogeneous catalyst [196]. This allowed better control of the selectivity and inhibited the auto oxidation of the active compound. In order to simulate a catalyst and the reaction conditions which are close to the enzymatic process, the so obtained catalyst was embedded in a polydimethylsiloxane membrane (mimics the phospholipid membrane in the living body) and the membrane was used to limit oxygen availability. With this catalyst alkanes were oxidized at room temperature with rates comparable to those of the enzyme [205]. 

Butadiene is used as a chemical intermediate and as a polymer component in the synthetic rubber industry, the latter accounting for 75% of the butadiene produced. Styrene-butadiene rubber, polybutadiene rubber, adiponitrile, styrene-butadiene latex, acrylonitrile-butadiene-styrene resins, and nitrile rubber are used in the manufacture of tires, nylon products, plastic bottles and food wraps, molded rubber goods, latex adhesives, carpet backing and pads, shoe soles, and medical devices. 

Caprolactam (6-hexanolactam), used in nylon production, can be made from aniline, by hydrogenation to cyclohexamine in the presence of a nickel-cobalt catalyst. The amine is then converted to cyclohexanone oxime. 

Tiling, G. Direct extrusion of nylon products from lactams. Modern Plastics 1969, 46 (18), 73 76. 

Bellussi. G. and Perego, C. (2000) Industrial catalytic aspects of the synthesis of monomers for nylon production. Cattech, 4. 4-16. 

To illustrate this technique, consider the dimerization of the acrylonitrile anion radical (AN") in DMF (26). The electroreductive hydrodimerization of AN is used commercially to produce adiponitrile [(ANH)2], a precursor in Nylon production. The proposed reaction mechanism, an E1.C2 reaction [Section 12.1.1(b)], is... 

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