Hexamethylene diamine, reaction with

Even though water has a low solubility in carbon dioxide, it has been shown that it can also be effectively removed with supercritical carbon dioxide in formation of nylon 66 (a polyamide) [34]. In this polyamide formation, because of the reactivity of carbon dioxide with amines, instead of using hexamethylene diamine, reaction was carried out with a nylon salt. Carbon dioxide was shown to lower the melting point of the nylon salt and permit polymerization to proceed at lower temperatures. At temperatures around 270 and over a reaction time of about 3 hr at 3000 psi polyamides of high molecular weight (Mn = 25,000) have been produced. 

Vulcanization of the epichlorhydrin rubbers is normally brought about by reaction of the chloromethyl group with diamines and polyamines or their derivatives such as hexamethylene diamine carbamate, with 2-mercaptobenzimidazoline, with lead oxide and lead phosphite, and with ammonium salts. The processes are analogous to those used with the polychloroprenes and with those acrylic rubbers containing a halogenated cure site. A sulphur-curable grade was announced in late 1977. 

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. 

Hexamethylene diamine (116 g), sodium carbonate (466 g), and water (800 ml) were heated to 60°C, and dimethyl sulfate (830 g) added with stirring over 1% hours keeping the temperature below 90°C. The reaction mixture was then stirred at 90°C for 2 hours, then cooled to 20°C, acetone (1,200 ml) added and the whole cooled to 0°C. 

The reaction of ACPC with linear aliphatic amines has been investigated in a number of Ueda s papers [17,35,36]. Thus, ACPC was used for a interfacia] polycondensation with hexamethylene diamine at room temperature [17] yielding poly(amide)s. The polymeric material formed carried one azo group per repeating unit and exhibited a high thermal reactivity. By addition of styrene and methyl methacrylate to the MAI and heating, the respective block copolymers were formed. 

The main use of acrolein is to produce acrylic acid and its esters. Acrolein is also an intermediate in the synthesis of pharmaceuticals and herhicides. It may also he used to produce glycerol hy reaction with isopropanol (discussed later in this chapter). 2-Hexanedial, which could he a precursor for adipic acid and hexamethylene-diamine, may he prepared from acrolein Tail to tail dimenization of acrolein using ruthenium catalyst produces trans-2-hexanedial. The trimer, trans-6-hydroxy-5-formyl-2,7-octadienal is coproduced. Acrolein, may also he a precursor for 1,3-propanediol. Hydrolysis of acrolein produces 3-hydroxypropionalde-hyde which could he hydrogenated to 1,3-propanediol. ... 

PA-6,6 is made from the relatively expensive materials hexamethylene diamine and adipic acid. An alternative synthesis of PA-6,6 from adiponitrile and hexamethylene diamine utilizing water is under investigation.16 PA-6 can be synthesized in a continuous process at atmospheric pressure, but reaction times are very long as the ring-opening initiation step is particularly slow. The reaction time can be shortened considerably by carrying out prepolymerization in the presence of excess water at pressure however, this makes the continuous polymerization process more complex. Copolymers with amide units of uniform length (diamides) are relatively new the diamide units are able to crystallize easily and have a thermally stable crystalline structure. 

PA-6,1 salt is made by adding 33.2 g of isophthalic acid to a reaction vessel with a reflux cooler filled with a 100-mL mixture of methanol and water (9 1). To this suspension, which is under nitrogen, 23.2 g of hexamethylene diamine in 20 mL of methanol is added slowly. The reaction mass is then allowed to cool whereby the nylon salt crystallizes. The precipitated salt is filtered, washed with methanol, and air dried. 

In 1930, DuPont launched the synthetic fiber industry with the discovery of nylon-6,6.2 In 1938, a pilot plant for nylon-6,6 production was put into operation, and in 1939, production was commenced at a large-scale plant in Seaford, Delaware. The classical method for the synthesis of nylon-6,6 involves a two-step process. In the first step, hexamethylene diamine (HMDA) is reacted with adipic acid (AA) to form a nylon salt. Polymerization of the aqueous salt solution is carried out at temperatures in the range of about 210-275°C at a steam pressure of about 1.7 MPa. When 275°C is reached, the pressure is reduced to atmospheric pressure and heating is continued to drive the reaction to completion. 

Figure 6.7 Reaction of wood with succinic anhydride (SA) and subsequent reaction of the activated surface with hexamethylene diamine (HMDA), using diisopropyl carbodiimide (DIPCI) as a reaction promoter.

The condensation polymers are formed by repeated condensation reaction between two different bi-functional or tri-functional monomeric units. In these pol3nnerisation reactions, the elimination of small molecules such as water, alcohol, hydrogen chloride, etc. take place. The examples are terylene (dacron), nylon 6, 6, nylon 6, etc. For example, nylon 6, 6 is formed by the condensation of hexamethylene diamine with adipic acid. 

The synthesis of polyamides follows a different route from that of polyesters. Although several different polymerization reactions are possible, polyamides are usually produced either by direct amidation of a diacid with a diamine or the self-amidation of an amino acid. The polymerization of amino acids is not as useful because of a greater tendency toward cycliza-tion (Sec. 2-5b). Ring-opening polymerization of lactams is also employed to synthesize polyamides (Chap. 7). Poly(hexamethylene adipamde) [IUPAC poly(iminohexanedioylimi-nohexane-l,6-diyl) or poly(iminoadipoyliminohexane-l,6-diyl)], also referred to as nylon 6/6, is synthesized from hexamethylene diamine and adipic acid [Zimmerman, 1988 Zimmerman and Kohan, 2001]. A stoichiometric balance of amine and carboxyl groups is readily obtained by the preliminary formation of a 1 1 ammonium salt (XU ) in aqueous solution at a concentration of 50%. The salt is often referred to as a nylon salt. Stoichiometric... 

A good example of template copolycondensation has been described by Ogata et al Copolycondensation of 2,6-dimethyl pyridine dicarboxylate and dimethyl adipate with hexamethylene diamine was carried out in the presence of polysaccharide - Pullulane (mol. weight 30,000) used as a template. The reaction was carried out in DMSO at 60 C. It was found that the content of 2,6-dimethyl pyridine dicarboxylate units in the copolyamide, determined by NMR analysis, increased in the presence of Pullulane in comparison with the amount obtained in the absence of the template. This effect can be explained by preferential adsorption by the template of monomer having pyridine groups in comparison with the adsorption of dimethyl adipate. A set of experiments was carried out under the same conditions, but in the presence of poly(acrylonitrile) instead of Pullulane. The composition of copolyamides was the same as in copolycondensation without the template. 

Investigation of template poly condensation kinetics has only been studied within a very narrow scope. Polymerization of dimethyl tartrate with hexamethylene diamine was found to be enhanced by using as a template poly(vinyl pyrrolidone), poly(2-vinyl pyridine), or polysaccharides and poly(vinyl alcohol), poly(4-vinyl pyridine). In this case, the template can be treated as a catalyst. No information exists on the influence of the template on the order of reaction. The increase in molecular weight of the polymerization product by the template can be induced by a shift of equilibrium or by an increase in the reaction rate. A similar increase in the reaction rate was observed when poly(4-vi-nyl pyridine) was used in the synthesis of poly(terephtalamides) activated by triphenyl phosphite.The authors suggested that a high molecular weight template was involved in the increase of the local concentration of the substrate (terephthalic acid) by adsorption and activation via N-phosphonium salt of poly(4- vinyl pyridine). 

Uses. The principal use of adiponitrile is for hydrogenation to hexamethylene diamine leading to nylon-6,6. Adipoquanamine, prepared by the reaction of adiponitrile with dicyandiamide (cyanoguanidine), has typical liquid nitrile properties that suggest its use as an extractant for aromatic hydrocarbons. 

In a similar way as has been described for syntheses of type al, the majority of examples of type b involve polycondensation of a,ea bifunctional, small molecule reaction partners. Some examples are the reaction of AIBN or AIBN derivatives with 1,4-cyclohexane bismethyl diamine78), 1,2-ethylene diamine78), 1,6-hexamethylene diamine 78-80 , bisphenol A 78,81 and mono-, di- and tetraethylene glycol 55-64 . In almost all case using the AIBN derivative 4,4 -azobis(4-cyano valeryl chloride), an interfacial polymerization was employed. These polymeric azo compounds could be used as initiators for radical block copolymerizations. 

We form an amide linkage between the adipoyl chloride and the amine with the elimination of HC1. The polymer is called nylon 6-6 because there are six carbon atoms in the acyl chloride and six carbon atoms in the diamine. Other nylons, such as nylon 10-6, are made of sebacoyl chloride (a 10-carbon atom containing acyl chloride) and hexamethylene diamine (a six carbon atom containing diamine). We use an acyl chloride rather than a carboxylic acid to form the amide bond because the former is more reactive. NaOH is added to the polymerization reaction in order to neutralize the HC1 that is released every time an amide bond is formed. 

Nylon is the common name for polyamides. Polyamides are generally made from reactions of diacids with diamines. The most common polyamide is called nylon 6,6 because it is made by reaction of a six-carbon diacid (adipic acid) with a six-carbon diamine. The six-carbon diamine, systematically named hexane-1,6-diamine, is commonly called hexamethylene diamine. When adipic acid is mixed with hexamethylene diamine, a proton-transfer reaction gives a white solid called nylon salt. When nylon salt is heated to 250 °C, water is driven off as a gas, and molten nylon results. Molten nylon is cast into a solid shape or extruded through a spinneret to produce a fiber. 

Quite often polymerisation proceeds by interaction of pairs of complementary monomers. Thus Nylon-6,6 is formed by reaction of adipic acid with hexamethylene diamine ... 

Condensation reactions can involve the splitting out of molecules other than water. For example, nylon 6,6 can be made from hexamethylene diamine and adipoyl chloride (instead of adipic acid). In this case a molecule of HCI is split or condensed out. There is a neat trick you can perform with this system that is commonly called The Nylon Rope Trick. The acid chloride will dissolve in an organic solvent, such as chloroform, while the diamine will dissolve in water. These two solutions do not want to mix and when carefully added to a beaker they form a phase-separated system. Polymerization can then occur at the interface between the phases (an iriterfacial polymerization), as illustrated in Figure 3-13. 

PMMA itself does not possess ready-to-use fiinctional groups for covalent binding with biological molecules. The amine-terminated PMMA were often produced by immersing the freshly cleaned PMMA substrate into a 1.0 M ethylenediamine in dimethyl sulfoxide (DMSO) solution for 15 min at room temperature (115) or coated with a thin layer of polyethyleneimine (PEI) or polyallylamine hydrochloride (PAH). This was first treated in 1 N sodium hydroxide (NaOH) solution at 55 C for 30 min and then immersed in a PEI or PAH solution (0.2%, pH 7) at room temperature for 1 h (117). Tsai and Lin (2005) demonstrated that PEI-derivatized PMMA was used for the determination of alpha-fetoprotein by quartz crystal microbalance (QCM) (118). Furthermore, the amine-terminated PMMA could be generated by reacting with 10% hexamethylene diamine (HMD) (reaction shown in scheme 8.2) or 1,3-diaminopropane (DAP) in 100 mM borate buffer pH 11.5 for 2 h (119) or exposing to -lithioethylenediamine (120) (reaction shown in scheme 8.3). 

Bulmus et al. (1997) demonstrated the modified PMMA mono-size microbeads for glucose oxidase immobilization, in which PMMA substrate was washed with 10% (w/v) NaOH followed by 50% (v/v) ethanol. Freshly cleaned PMMA was then immersed in a solution of 1 g/L polyvinyl alcohol for 20 min, followed by oxidation reaction with a solution of 1% NaI04 for 1 h at room temperature. The amino functionality was then added by using a solution of 10% (w/v) hexamethylene diamine in 100 mM borate buffer pH 11.5, for 2 h (123) (shown in scheme 8.5). 

A/f-copolymers have a unique situation among macromolecular compounds. They have an ordered structure of the type -[A-B-]n, which can be viewed as the structure of a homopolymer. The fact that a/f-copolymers can be formed from two starting monomers is not their unique property, and many homopolymers formed in step reactions have an -[A-B-]n formula. For example. Nylon 66, being formed from adipic acid and 1,6-hexandiamine, can be considered an a/f-copolymer and named poly(hexamethylene-diamine-a/f-adipic acid), or it can have the name poly(hexamethylene adipamide) or poly(iminohexa-methylene iminoadipoyl) and be viewed as a homopolymer with the structure -[NH-(CH2)6-NHC(0)-(CH2)4-C(O)-]n. Many other examples of the same type can be listed. 

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