Mixtures diamine

The polyamide copolymer of dodecanoic acid with methylenedi(cyclohexylamine) (MDCHA, PACM) was sold as continuous filament yam fiber under the tradename QIANA. As late as 1981, over 145,000 t was produced using high percentages, typically 80%, of trans, trans MDCHA isomer. The low melting raffinate coproduct left after t,t isomer separation by fractional crystallisation was phosgenated to produce a Hquid aUphatic diisocyanate marketed by Du Pont as Hylene W. Upon terrnination of their QIANA commitment, Du Pont sold the urethane intermediate product rights to Mobay, who now markets the 20% trans, trans—50% cis, trans—30% cis, cis diisocyanate isomer mixture as Desmodur W. In addition to its use in polyamides and as an isocyanate precursor, methylenedi (cyclohexyl amine) is used directiy as an epoxy curative. The Hquid diamine mixture identified historically as PACM-20 is marketed as AMICURE PACM by Anchor Chemical for performance epoxies. 

The synthesis of TDI begins with the nitration of toluene, using a nitric acid-sulfuric acid mixture. The nitration product typically contains at least 75 percent 2,4-dinitrotoluene with the balance mostly 2,6-dinitrotoluene, which is catalytically reduced to toluene diamine. Lastly, the diamine mixture is dissolved in chlorobenzenes and reacted with... 

NASA-Langley provided a further improvement in processibility by replacing the methylenedianiline with a commercial aromatic diamine mixture that afforded even better handling characteristics (17). This type of product is formed by the reaction of formaldehyde with aniline as a precursor in isocyanate manufacture. Fluorine-containing thermoplastic polyimides and polyimides end capped with acetylene groups for cross-linking are also available as potential commercial high-temperature resins. 

Scheme 3 Reversed halide exchange catalyzed by copper (I)/diamine mixture...

In order to obtain a phase diagram in conversion-composition coordinates, a particular system consisting of a diepoxide based on diglycidylether of bis-phenol A (DGEBA), a stoichiometric amount of a diamine (4,4 -diamino-3,3 -dimethyldicyclohexyl-methane, 3DCM), as a hardener, and a rubber based on a statistical copolymer of butadiene and acrylonitrile, will be considered [65]. The increase in the number-average molar mass for the polycondensation of a stoichiometric diepoxy-diamine mixture, is given by [65]... 

The resulting isomer mixture is washed with water and ammonia, centrifuged to remove acid and phenolic by-products and then catalytically hydrogenated [39]. MPD is isolated from the crude diamine mixture and purified by selective distillation (Equation 13.2)... 

The mixture of 2,2,4- and 2,4,4-trimethyl hexamethylene diamine gives a highly transparent, clear, amorphous polyamide after polycondensation with terephthalic acid. To produce the diamine mixture, acetone is tri-merized to isophorone, which subsequently splits into a mixture of 2,2,4-and 2,4,4-trimethyl adipic acid ... 

Toluene diisocyanates are prepared by direct nitration of toluene to give an 80 20 mixture of the 2,4- and 2,6-dinitro derivatives, followed by hydrogenation to the corresponding diaminotoluenes. Under conditions where the 2-nitrotoluene is first separated and further nitrated, a 65 35 mixture of the dinitro compounds and ultimately of the diamines results. The diamine mixtures are treated with phosgene at temperatures up to 140°C and the derived diisocyanate mixture is isolated and purified by distillation. The two (2,4 and 2,6) isomers differ considerably in reactivity (Table 1.1), so the actual ratio of the two components can be quite important. For many purposes the 80 20 mixture is preferred. The preparation route for the production of TDI is detailed in Fig. 1.7a. 

Sir-Hashim M, Hamza YO, Yahia B, Khogali FM, Sulieman GI (1992) Poisoning from henna dye and para phenylene-diamine mixtures in children in Khartoum. Ann Trop Paediatr 12 3-6... 

In synthesis of ferrierite, dry aluminosilicate gels were used in methanolic [93K2] or ethanolic [95D1] media with piperidine and dibutylamine/ethylene diamine mixtures, respectively, as template. 

The above diamines can alternatively be identified as their diacetyl derivatives. Heat under reflux 0 5 g. of the diamine with 3 ml. of acetic acid—NaOH solution will cause the separation of the diacetyl derivative. Recrystallise from ethanol. M.ps. of the diacetyl derivatives of 0-, m-, and />-phenylene diamine are 185 , 191 , and 304 respectively (p. 551). 

Finally, in the last step, the chelating auxiliary had to be removed Ideally, one would like to convert 4.54 into ketone 4.55 via a retro Mannich reaction. Unfortunately, repeated attempts to accomplish this failed. These attempts included refluxing in aqueous ethanol under acidic and basic conditions and refluxing in a 1 1 acetone - water mixture in the presence of excess paraformaldehyde under acidic conditions, in order to trap any liberated diamine. Tliese procedures were repeated under neutral conditions in the presence of copper(II)nitrate, but without success. 

Note 1. A considerable part of the diamine can be recovered by distilling it off from the reaction mixture, using a bath temperature not exceeding 5Q°C. 

The Showa Denka Company practices this reaction with a PX—MX mixture (24), whereas Mitsubishi Gas Chemical Company uses high purity MX first to form the dicyanide (25). In both processes, hydrogenation to the diamine follows. y -Xylenediamine is reacted with phosgene to give / -xylene diisocyanate, which is used in urethane resins (26—28). 

Lewis acids, such as the haUde salts of the alkaline-earth metals, Cu(I), Cu(II), 2inc, Fe(III), aluminum, etc, are effective catalysts for this reaction (63). The ammonolysis of polyamides obtained from post-consumer waste has been used to cleave the polymer chain as the first step in a recycle process in which mixtures of nylon-6,6 and nylon-6 can be reconverted to diamine (64). The advantage of this approach Hes in the fact that both the adipamide [628-94-4] and 6-aminohexanoamide can be converted to hexarnethylenediarnine via their respective nitriles in a conventional two-step process in the presence of the diamine formed in the original ammonolysis reaction, thus avoiding a difficult and cosdy separation process. In addition, the mixture of nylon-6,6 and nylon-6 appears to react faster than does either polyamide alone. 

Diesters of Tetracarboxylic Acids with Diamines. Dianhydrides react with alcohols at a moderate temperature, producing the tetracarboxyhc acid diesters. Ben2ophenonetetracarboxyhc acid diester (BTTA diester) is obtained from B I DA as a mixture of three positional isomers. Partiy because it is an isomeric mixture, the diester of BTTA is soluble in methanol at high concentrations. A state-of-the-art thermoset polyimide,... 

Table 3 fists cycloaliphatic diamines. Specific registry numbers are assigned to the optical isomers of /n t-l,2-cyclohexanediamine the cis isomer is achiral at ambient temperatures because of rapid interconversion of ring conformers. Commercial products ate most often marketed as geometric isomer mixtures, though large differences in symmetry may lead to such wide variations in physical properties that separations by classical unit operations are practicable, as in Du Font s fractional crystallisation of /n t-l,4-cyclohexanediamine (mp 72°C) from the low melting (5°C) cis—trans mixture. 

Dicyclopentadiene (24) [77-73-6] is an inexpensive raw material for hydrocyanation to (25), a mixture of l,5-dicarbonittile [70874-28-1] and 2,5-dicarbonittile [70874-29-2], then subsequent hydrogenation to produce tricyclodecanediamine, TCD diamine (26). This developmental product, a mixture of endo and exo, cis and trans isomers, is offered by Hoechst. 

Cycloahphatic diamines which have reacted with diacids to form polyamides generate performance polymers whose physical properties are dependent on the diamine geometric isomers. (58,74). Proprietary transparent thermoplastic polyadipamides have been optimized by selecting the proper mixtures of PDCHA geometric isomers (32—34) for incorporation (75) ... 

Isocyanates. The commodity isocyanates TDI and PMDI ate most widely used in the manufacture of urethane polymers (see also Isocyanates, organic). The former is an 80 20 mixture of 2,4- and 2,6-isomers, respectively the latter a polymeric isocyanate obtained by phosgenation of aniline—formaldehyde-derived polyamines. A coproduct in the manufacture of PMDI is 4,4 -methylenebis(phenyHsocyanate) (MDI). A 65 35 mixture of 2,4- and 2,6-TDI, pure 2,4-TDI and MDI enriched in the 2,4 -isomer are also available. The manufacture of TDI involves the dinitration of toluene, catalytic hydrogenation to the diamines, and phosgenation. Separation of the undesired 2,3-isomer is necessary because its presence interferes with polymerization (13). 

Bismaleimides are best defined as low molecular weight, at least diftinctional monomers or prepolymers, or mixtures thereof, that carry maleimide terminations (Eig. 3). Such maleimide end groups can undergo homopolymerization and a wide range of copolymerizations to form a highly cross-linked network. These cure reactions can be effected by the appHcation of heat and, if required, ia the presence of a suitable catalyst. The first patent for cross-linked resias obtained through the homopolymerization or copolymerization of BMI was granted to Rhc ne Poulenc, Erance, ia 1968 (13). Shordy after, a series of patents was issued on poly(amino bismaleimides) (14), which are synthesized from bismaleimide and aromatic diamines. 

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