Hexamethylenediamine, from

Figure 10.3 Manufacture of adiponitrile and hexamethylenediamine from 1,3-butadiene.

Polyamides from diamines and dibasic acids. The polyamides formed from abphatic diamines (ethylene- to decamethylene-diamine) and abphatic dibasic acids (oxabc to sebacic acid) possess the unusual property of forming strong fibres. By suitable treatment, the fibres may be obtained quite elastic and tough, and retain a high wet strength. These prpperties render them important from the commercial point of view polyamides of this type are cabed nylons The Nylon of commerce (a 66 Nylon, named after number of carbon atoms in the two components) is prepared by heating adipic acid and hexamethylenediamine in an autoclave ... 

Neutrahse about one third of the filtrate with 5N sodium hydroxide and add a further 2 ml. of the alkah solution. Add 1 ml. of benzoyl chloride and stir until the odour of the acid chloride disappears. Collect the solid by suction filtration, wash it with water until free from alkah, and then recrystalhse it from dilute alcohol. The product is the dibenzoyl derivative of hexamethylenediamine and melts at 159°. 

The nomenclature (qv) of polyamides is fraught with a variety of systematic, semisystematic, and common naming systems used variously by different sources. In North America the common practice is to call type AB or type AABB polyamides nylon-x or nylon-respectively, where x refers to the number of carbon atoms between the amide nitrogens. For type AABB polyamides, the number of carbon atoms in the diamine is indicated first, followed by the number of carbon atoms in the diacid. For example, the polyamide formed from 6-aminohexanoic acid [60-32-2] is named nylon-6 [25038-54-4], that formed from 1,6-hexanediamine [124-09-4] or hexamethylenediamine and dodecanedioic acid [693-23-2] is called nylon-6,12 [24936-74-1]. In Europe, the common practice is to use the designation "polyamide," often abbreviated PA, instead of "nylon" in the name. Thus, the two examples above become PA-6 and PA-6,12, respectively. PA is the International Union of Pure and AppHed Chemistry (lUPAC) accepted abbreviation for polyamides. 

Ingredients. Nylon-6,6 is made from the reaction of adipic acid [124-04-9] and hexamethylenediamine [124-09-4]. The manufacture of intermediates for polyamides is extremely important not only is the quaUty of the polymer, such as color, degree of polymerization, and linearity, strongly dependent on the ingredient quaUty, but also the economic success of the producer is often determined by the yields and cost of manufacture of the ingredients. 

In the final step the dinitrile is formed from the anti-Markovrukov addition of hydrogen cyanide [74-90-8] at atmospheric pressure and 30—150°C in the hquid phase with a Ni(0) catalyst. The principal by-product, 2-methylglutaronitrile/4j5 j5 4-ti2-, when hydrogenated using a process similar to that for the conversion of ADN to hexamethylenediamine, produces 2-meth5i-l,5-pentanediamine or 2-methylpentamethylenediamine [15520-10-2] (MPMD), which is also used in the manufacture of polyamides as a comonomer. 

Nylon-6,9, Nylon-6,10, and Nylon-6,12. These nylons are all produced from hexamethylenediamine and either azelaic, sebacic, or dodecanoic acid. They are produced by a process similar to that for nylon-6,6, usually using batch autoclaves. 

The manufacture of hexamethylenediamine [124-09-4] a key comonomer in nylon-6,6 production proceeds by a two-step HCN addition reaction to produce adiponittile [111-69-3] NCCH2CH2CH2CH2CN. The adiponittile is then hydrogenated to produce the desired diamine. The other half of nylon-6,6, adipic acid (qv), can also be produced from butadiene by means of either of two similar routes involving the addition of CO. Reaction between the diamine and adipic acid [124-04-5] produces nylon-6,6. 

An example of the first route is given in the preparation of nylon 66, which is made by reaction of hexamethylenediamine with adipie acid. The first 6 indicates the number of carbon atoms in the diamine and the second the number of carbon atoms in the acid. Thus, as a further example, nylon 6.10 is made by reacting hexamethylenediamine with sebacic acid (HOOC (CH2)s"COOH). (In this context the numbers 10,11 and 12 are considered as single numbers the need to use two digits results simply from the limitations of the decimal system.)... 

Hexamethylenediamine may be conveniently prepared from adipic acid via adiponitrile... 

In a typical process adiponitrile is formed by the interaction of adipic acid and gaseous ammonia in the presence of a boron phosphate catalyst at 305-350°C. The adiponitrile is purified and then subjected to continuous hydrogenation at 130°C and 4000 Ibf/in (28 MPa) pressure in the presence of excess ammonia and a cobalt catalyst. By-products such as hexamethyleneimine are formed but the quantity produced is minimized by the use of excess ammonia. Pure hexamethylenediamine (boiling point 90-92°C at 14mmHg pressure, melting point 39°C) is obtained by distillation, Hexamethylenediamine is also prepared commercially from butadience. The butadiene feedstock is of relatively low cost but it does use substantial quantities of hydrogen cyanide. The process developed by Du Pont may be given schematically as ... 

The following is an alternative route 19.4 parts of p-chlorophenyidicyandiamide, 9.4 parts of hexamethylenediamine dihydrochloride and 100 parts of nitrobenzene are stirred together and heated at 150°C to 160°C for 6 hours. The mixture Is cooled, diluted with 200 parts of benzene and filtered. The solid residue is washed with benzene and crystallized from 50% acetic acid. 1,6-di(Ni, Ni -p-chlorophenyldiguanido-Ns,Ns )hexane dihydrochloride Is obtained. 

Interfacial polycondensation between a diacid chloride and hexamethylenediamine in the presence of small amounts of ACPC also yield polymeric azoamid, which is a macroazo initiator.[27] In this manner, azodicarbox-ylate-functional polystyrene [28], macroazonitriles from 4,4 -azobis(4-cyano-n-pentanoyl) with diisocyanate of polyalkylene oxide [29], polymeric azo initiators with pendent azo groups [3] and polybutadiene macroazoinitiator [30] are macroazoinitiators that prepare block and graft copolymers. 

The most important AA-BB-type polymer is PA-6,6. It is a semicrystalline material and has a high melting temperature (265°C). PA-6,6 is prepared from 1,6 hexamethylenediamine and adipic acid (Eq. 3.27) ... 

PA-6,10 is synthesized from 1,6-hexamethylenediamine and sebacic acid, and PA-6,12 from 1,6-hexamethylenediamine and dodecanedioic acid. The melt synthesis from their salts is very similar to PA-6,6 (see Example 1). These diacids are less susceptible to thermal degradation.55 PA-6,10 can also be synthesized by interfacial methods at room temperature starting with the very reactive sebacyl dichloride.4 35 A demonstration experiment for interfacial polycondensation without stirring can be carried out on PA-6,10. In this nice classroom experiment, a polymer rope can be pulled from the polymerization interface.34... 

Step polymerisations tend to be carried out using two different bifunctional molecules so that these give rise to molecules which are essentially copolymers. For example, nylon 6,6 is prepared from hexamethylenediamine and adipic acid it thus consists of alternating residues along the polymer chain and may be thought of as an alternating copolymer. 

Type 66 nylon is a polyamide first commercialized by DuPont just prior to World War II. At that time, the needed hexamethylenediamine was made from adipic acid by reaction with ammonia to adiponitrile followed by reaction with hydrogen. The adipic acid then, like now, was made from cyclohexane. The cyclohexane, however, was derived from benzene obtained from coal. The ammonia was made from nitrogen in the air by reaction with hydrogen from water obtained in the water-gas shift reaction with carbon monoxide from the coal. So, in the 1950s, nylon was honestly advertised by DuPont as being based on coal, air, and water. 

Hexamethylenediamine is now made by three different routes the original from adipic acid, the electrodimerization of acrylonitrile, and the addition of hydrogen cyanide to butadiene. Thus, the starting material can be cyclohexane, propylene, or butadiene. Currently, the cyclohexane-based route from adipic acid is the most costly and this process is being phased out. The butadiene route is patented by DuPont and requires hydrogen cyanide facilities. Recent new hexamethylenediamine plants, outside DuPont, are based on acrylonitrile from propylene, a readily available commodity. 

Nylon 66 was the first polyamide to be produced commercially. Developed by Wallace Carothers at the DuPont Chemical Company In 1935, it still leads the polymer industry in annual production. Figure 13-7 illustrates that Nylon 66, made from adipic acid and hexamethylenediamine, is so easy to make that it is often used for a classroom demonstration ... 

Fig. 12a,b. The sensorgrams for the binding of the antibody dendrimer (a) or IgG (b) to the anionic porphyrin immobilized onto the surface of the sensor chip. Phosphate borate buffer (0.1 M, pH 9.0) was used. TCPP was immobilized via hexamethylenediamine spacer onto the sensor chip and then a solution of IgG or the dendrimer was injected to the flow cell. After 60 s from the injection of the antibody solutions, flow ceU was filled with buffer... 

Adiponitrile is readily hydrogenated catalytically to hexamethylenediamine, which is an important starting material for the prodnction of nylons and other plastics. The electrochemical production of adiponitrile was started in the United States in 1965 at present its volume is about 200 kilotons per year. The reaction occurs at lead or cadmium cathodes with current densities of np to 200 mA/cm in phosphate buffer solutions of pH 8.5 to 9. Salts of tetrabntylammonium [N(C4H9)4] are added to the solution this cation is specihcally adsorbed on the cathode and displaces water molecules from the first solution layer at the snrface. Therefore, the concentration of proton donors is drastically rednced in the reaction zone, and the reaction follows the scheme of (15.36) rather than that of (15.35), which wonld yield propi-onitrile. 

Hexamethylenediamine (HMDA), a monomer for the synthesis of polyamide-6,6, is produced by catalytic hydrogenation of adiponitrile. Three processes, each based on a different reactant, produce the latter coimnercially. The original Du Pont process, still used in a few plants, starts with adipic acid made from cyclohexane adipic acid then reacts with ammonia to yield the dinitrile. This process has been replaced in many plants by the catalytic hydrocyanation of butadiene. A third route to adiponitrile is the electrolytic dimerization of acrylonitrile, the latter produced by the ammoxidation of propene. 

How can you make a polyester and a polyamide Objectives Prepare a polyester from phthalic anhydride and ethylene glycol. Prepare a polyamide from adipoyl chloride and hexamethylenediamine. phthalic anhydride (2.0 g) sodium acetate (0.1 g) ethylene glycol (1 mL) 5% adipoyl chloride in cyclohexane (25 mL) 50% aqueous ethanol (10 mL) 5% aqueous solution of hexamethylenediamine (25 mL) 20% sodium hydroxide (NaOH) (1 mL) scissors copper wire test tube test-tube rack 10-mL graduated cylinder 50-mL graduated cylinder 150-mL beakers (2) ring stand clamp Bunsen burner striker or matches balance weighing papers (2)... 

A process for the hydrogenation of adiponitrile and 6-aminocapronitrile to hexamethylenediamine in streams of depolymerized Nylon-6,6 or a blend of Nylon-6 and Nylon-6,6 has been described. Semi-batch and continuous hydrogenation reactions of depolymerized (ammonolysis) products were performed to study the efficacy of Raney Ni 2400 and Raney Co 2724 catalysts. The study showed signs of deactivation of Raney Ni 2400 even in the presence of caustic, whereas little or no deactivation of Raney Co 2724 was observed for the hydrogenation of the ammonolysis product. The hydrogenation products from the continuous run using Raney Co 2724 were subsequently distilled and the recycled hexamethylenediamine (HMD) monomer was polymerized with adipic acid. The properties of the polymer prepared from recycled HMD were found to be identical to that obtained from virgin HMD. 

Hexamethylenediamine (HMD) and adiponitrile (ADN) are formed from Nylon-6,6, while 6-aminocapronitrile (ACN) and caprolactam (CL) are formed from Nylon-6. The ammonolysis product, which also contains many minor byproduct components, is fractionated by distillation with the HMD, ACN, ADN, and CL in one fraction. This fraction is subsequently hydrogenated to form HMD. Caprolactam remains intact during the hydrogenation reaction. 

The hydrogenation products from the continuous run using Raney Co 2724 were subsequently distilled and the product hexamethylenediamine monomer (i.e. recycled HMD ) was polymerized with adipic acid. The properties of the polymer prepared from recycled HMD were found to be identical to that obtained from virgin HMD, indicating that the continuous hydrogenation of ammonolysis product offers potential for the commercial production of recycled Nylon. 

When the reactants involved in a step growth polymerization process are mutually immiscible, we can employ an interfacial polymerization method. Two solutions, each containing one of the monomers, are layered one on top of the other. This creates a phase boundary that forms wth the least dense liquid on top. The different monomers can then meet and polymerize at the interface. A commonly demonstrated example of this is the manufacture of nylon 610 by the interfacial reaction between an aqueous solution of hexamethylenediamine with sebacoyl chloride dissolved in carbon tetrachloride. Because the reaction only occurs at the interface, it is possible to pull the products from this interface to isolate the final product. 

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