Nylon precursors synthesis

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 ... 

Epoxy-clay nanocomposites from epoxide precursors have been investigated by research groups at Michigan State University [34-40], Cornell University [41], and Case Western Reserve University [42,43]. In general, the synthesis is similar to that of Nylon-6 and PS... 

Oxidation is the first step for producing molecules with a very wide range of functional groups because oxygenated compounds are precursors to many other products. For example, alcohols may be converted to ethers, esters, alkenes, and, via nucleophilic substitution, to halogenated or amine products. Ketones and aldehydes may be used in condensation reactions to form new C-C double bonds, epoxides may be ring opened to form diols and polymers, and, finally, carboxylic acids are routinely converted to esters, amides, acid chlorides and acid anhydrides. Oxidation reactions are some of the largest scale industrial processes in synthetic chemistry, and the production of alcohols, ketones, aldehydes, epoxides and carboxylic acids is performed on a mammoth scale. For example, world production of ethylene oxide is estimated at 58 million tonnes, 2 million tonnes of adipic acid are made, mainly as a precursor in the synthesis of nylons, and 8 million tonnes of terephthalic acid are produced each year, mainly for the production of polyethylene terephthalate) [1]. 

The transition metal catalysed addition of HCN to alkenes is potentially a very useful reaction in organic synthesis and it certainly would have been more widely applied in the laboratory if its attraction were not largely offset by the toxicity of HCN. Industrially the difficulties can be minimised to an acceptable level and we are not aware of major accidents. DuPont has commercialised the addition of HCN to butadiene for the production of adiponitrile [ADN, NC(CH2)4CN], a precursor to 1,6-hexanediamine, one of the components of 6,6-nylon and polyurethanes (after reaction with diisocyanates). The details of the hydrocyanation process have not been released, but a substantial amount of related basic chemistry has been published. The development of the ligand parameters % and 0 by Tolman formed part of the basic studies carried out in the Du Pont labs related to the ADN process [1],... 

Electroorganic synthesis deals with conversion of organic compounds into useful products by anodic oxidation or cathodic reduction. Today there exist literally thousands of published examples of electrosynthesis reactions but only a very small number—certainly not more than several tens—are really exploited commercially, the best known example being the cathodic hydrodimerization of acrylonitrile to adipodinitrile, a precursor to hexam-ethylene diamine, which is the aminoconstituent of nylon 6,6 (779) ... 

The most important use is the hydrocyanation of butadiene to adiponitrile, NC—(CH2)4—CN, a precursor to hexamethylenediamine for the synthesis of nylon. The process goes stepwise. The first addition of HCN involves nickel allyl intermediates and gives a mixture of linear and branched products in a ratio of —70 30. 

This type of reaction is now of major industrial importance because it constitutes a straiglitforward synthesis of nitriles. Wlien it is applied to a diolefm, such as butadiene, it leads to the formation of dinitriles, which are precursors of valuable monomers for the preparation of polymers (butadiene leads to adipo-nilrile. a nylon-b, fvprecursor). Du Font developed the first commercial process using butadiene and HCN for adiponitrile synthesis from butadiene, but this process does nut proceed through a hydrocyanation reaction it is. in fact, a copper-catalyzed halogenation reaction followed by a cyanaikm reaction (tquaiion (16)) of the chlorinated intermediate (Fquation (17)). 

A convenient random-priming method is labeling on a nylon membrane. Template can be spotted on the membrane, but it is also possible to use DNA restriction fragments transferred after electrophoretic separation onto nylon membranes (Chapter 9). DNA fixed on nylon membranes can serve as a template and the unincorporated precursors can be removed by simple washing for 1-2 min. The probe is then eluted from the membrane in formamide or in water. These membrane-bound DNAs can be reused. The probes synthesized by this method are as efficient in detecting nucleic acid as those synthesized in solution (Bhat, 1990). Similar methods have been proposed earlier for the synthesis of ij DNA probes from M13 templates (Ashley and MacDonald, 1984 Hansen et al., 1987). 

In the course of a continuous search for new strategies to produce Nylon monomers, the DSM company has described an attractive approach for the synthesis of adipic acid or 6-aminocaproic acid precursors. Indeed, in a recent patent, this company has claimed the hydroformylation of 3-pentenoic acid into 5-formylvaleric acid in biphasic medium (Eq. 3). With a water-soluble platinum complex of tetra-sulfonated trans-1,2-bis(diphenylphosphinomethylene)cyclobutane as catalyst, the selectivity for 5-formylvaleric acids reached 62% [15]. The same catalytic system allows also the hydroformylation of trans-3-pentenenitrile with 91.4% selectivity. 

Hexamethylenediamine (HMDA) is a precursor for nylon 6/6. There are numerous routes to HMDA, but all of the commercial processes involve the synthesis of adiponitrile and the subsequent hydrogenation of adiponitrile to HMDA. The dominant process is the reaction of hydrogen cyanide with 1,3 butadiene to form adiponitrile followed by hydrogenation of adiponitrile to hexamethylene diamine. 

The synthesis of lactames has interest for the production of chemicals and fine chemicals. In the case of more bulky lactames derived from cyclodedecanone-oxime and cyclooctanone-oxime, they are used for producing nylon-12 and for the preparation of the precursor of azacycloalkanediphosphonic derivates which have pharmaceutical interest for the treatment of Ca metabolism disorders, respectively. 

Ithough there are many different derivatives of carboxyiic acids, variations that can account for miiiions of distinct organic moiecuies, the vast majority can arise via a common and mechanisticaiiy consistent bond-formation process. This event is known as nucieophiiic acyi substitution, and it invoives the creation of a new bond by a nucieophiiic addition and eiimination at a carbonyl group. This process is utilized industrially in the synthesis of complex polymers, such as nylon and polyesters (see Special Topic C in WileyPLUS). It also occurs in metabolism, in the synthesis of proteins, fats, and steroid precursors, as well as in the breakdown of food for energy and for other biosynthetic raw materials (see Special Topic E in WileyPLUS). Its versatility is truly amazing. 

The motivation for Monsanto to pursue this technology may be understood by an awareness of the synthesis of Nylon 66, shown schematically below. Adipic acid (XXVI) is a key intermediate in the process, being a precursor to hexamethylenediamine (XXVII) and itself polymerized with the... 

Polyesters, nylon, and many biological molecules share a common aspect of bond formation during their synthesis. This process is called acyl substitution, and it involves creation of a bond by nucleophilic addition and elimination at a carbonyl group. Acyl substitution reactions occur every moment of every day in our bodies as we biosynthesize proteins, fats, precursors to steroids, and other molecules and as we degrade food molecules to provide energy and biosynthetic raw materials. Acyl substitution reactions are used virtually nonstop in industry as well. Approximately 3 billion pounds of nylon and 4 billion pounds of polyester fibers are made by acyl substitution reactions every year. The molecular graphic above is a portion of a nylon 6,6 polymer. 

It is well know that nickel(O) complexes play a crucial role in the commercial synthesis of adiponitrile (AdN), the major nylon-6,6 precursor. In the global process, the isomerization of the branched 2-methyl-3-butenenitrile (2M3BN) to the linear 3-pentenenitrile (3PN) is a key step. " Such isomerization is obtained through the C-CN bond activation involving a Ni° intermediate. 

HCN is the precursor to sodium cyanide and potassium cyanide, which are used mainly in mining. Via the intermediacy of cyanohydrins, a variety of useful organic compounds are prepared from HCN including the monomer methyl methacrylate, from acetone, the amino acid methionine, via the Strecker synthesis, and the chelating agents EDTA and NTA. Via the hydrocyanation process, HCN is added to butadiene to give adiponitrile, a precursor to Nylon 66. 

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