Polymers reaction with, phosgene

Polyanhydrides of terephthalic acid (10.39), isophthalic acid (10.40), and sebacic acid (10.41), were prepared by reaction with phosgene in toluene in the presence of NEtj [1865]. The polymers all have the general structure 10.42 X = l,4-CgH4, 1,3-CgH or (CHj). ... 

Polyurethane chemolysis can be performed by processes similar to those applied to PET. Thus, polyurethane glycolysis yields a mixture of polyols, which can be reused in the formulation of new polyurethanes. Likewise, polyurethane hydrolysis leads to the formation of polyols, diamines and carbon dioxide. The diamine can be subsequently transformed into the corresponding isocyanate by reaction with phosgene, whereas the polymer-... 

Primary aliphatic diamines are very important intermediates in polymer industry. Tetramethylene diamine is a monomer for polyamide 4,6. Hexame-thylene diamine is used in two main industrial productions. Copolymerisation with adipic add gives rise to nylon 6,6. Reaction with phosgene leads to isocyanates which are monomers for painting industry. Methylpenta-methylene diamine is a monomer for thermoplastics (DU PONT s DYTEK). 

To attach heparin to poly(ether-urethanes) Kim et al. created amine functionality in the polymers by hydrolysis with sodium hydroxide subsequent reaction with phosgene converted amino into isocyanate groups which could then be coupled to the carboxyl groups in heparin. Obviously this procedure must result in some degradation of the poly(ether-urethane). 

Polyester carbonates can be prepared by the copolymerization of BPA with diacyl chlorides such as iso- or terephthaloyl chloride (eq. (14)) (86). These polymers have been commercialized by Bayer AG, GE, Dow Chemical, and Mitsubishi Chemical, Ltd. Melt processes to prepare these materials have also been demonstrated. In some cases, a diacid can be used directly because reaction with phosgene... 

Formation of N-Carboxy-(X-Amino AeidAnhydride (NCA) (85), NCAs are important as starting materials for amino acid polymers. They are prepared by the reaction of amino acids with phosgene in an aptotic solvent. 

Polycondensation of Bisphenols, II, with Phosgene. Polycondensation of siloxane-linked bisphenols, II, with phosgene is the most obvious synthetic approach leading to siloxane-modified poly(arylene carbonates) since the phosgene-bisphenol polycondensation is used in the synthesis of aromatic polycarbonates (1). This method was used initially to prepare polymer (as indicated in reaction 1) as well as for the attempted synthesis of polymers 2 and 5 ... 

The two key isocyanates that are used in the greatest volumes for polyurethane polymers are toluene diisocyanate (TDl) and methylene diphenyl diisocyanate (MDl). Both isocyanates are produced first by nitration of aromatics (toluene and benzene, respectively), followed by hydrogenation of the nitro aromatics to provide aromatic amines. In the case of MDl, the aniline intermediate is then condensed with formaldehyde to produce methylene dianiline (MDA), which is a mixture of monomeric MDA and an oligomeric form that is typical of aniline/formaldehyde condensation products [2]. The subsequent reaction of phosgene with the aromatic amines provides the isocyanate products. Isocyanates can also be prepared by the reaction of aromatic amines with dimethylcarbonate [3, 4]. This technology has been tested at the industrial pilot scale, but is not believed to be practiced commercially at this time. 

Isocyanates are produeed almost exclusively by the reaction of amines with phosgene (COCy, with the speeifie reaetion eonditions varying particularly for aromatic and aliphatic isocyanates (Chadwick and Cleveland 1981 Codd et al. 1972 Ulrich 1989). Aliphatic diisocyanates are produced by reaction of phosgene with either a slurry of the carbamate salts obtained in the reaction of the aliphatic diamines with earbon dioxide, or with a slimy of the amine hydrochloride (Ulrich 1989). Hexamethylene diisocyanate (HDI) is produeed by the reaction of phosgene with the amine salt (Chadwick and Cleveland 1981). The trimerie HDI biuret (HDI-BT), which has a low monomer content and is widely used in the formulation of exeeptionally high quality polymer coatings, is produced by controlled reaction of HDI with water, a water generator, or an amine (Chadwick and Cleveland 1981). 

Isocyanates are compounds with the general formula R-N=C=0. They have numerous uses in chemical synthesis, particularly in the manufacture of polymers with carefully tuned specialty properties. Methyl isocyanate is a raw material in the manufacture of carbaryl insecticide. Methyl isocyanate (like other isocyanates) can be synthesized by the reaction of a primary amine with phosgene in a moderately complex process, represented by reaction 15.8.1. Structures of three significant isocyanates are given in Figure 15.7. 

Polycarbonates are a class of thermoplastic polymers that are used in the plastic lenses of eyeglasses and in the shells of bicycle helmets. A polycarbonate is made from the reaction of bisphenol A (BPA) with phosgene (COCl2) ... 

Some polysulfides contain in the polymer backbone other groups besides -S-. A common type of group is oxycarbonyloxy, such as in the polymer resulting from the reaction of phosgene (chloroformyl chloride or carbonic acid dichloride) with 4,4 -thiobisphenol. This reaction can be considered a polycondensation and can be written as follows ... 

When a diisocyanate reacts with a diol, a linear polyurethane is generated, and when it reacts with a polyol, it generates a cross-linked polymer. The isocyanates are commonly prepared by the reaction of phosgene and primary amines as follows ... 

The reaction between ethyne and phosgene has also been studied under photochemical conditions (>220 nm) [2185a]. As in the analogous reaction with ethene (see Section 10.1.2), the phosgene merely acts as a convenient source of chlorine radicals the principal products were CO, CHj=CHCl, 1-chloro-l, 3-butadiene, benzene and polymer trace amounts of HC Cl and CgHjCl were also detected [2185a]. 

The early chemical literature concerning the reactions of phosgene with aldehydes is fraught with confusion. The product of the reaction of phosgene with ethanal, for example, has been variously reported as a polymer [1078b], a gem-dichloride [582], a chloroformate [322], or (ludicrously) a material isomeric with vinyl chloride (chloroethene) [685c,887,1164a]. Only recently has this situation been satisfactorily resolved [1765]. 

Phosgene is very commonly employed in polymerisation reactions. Its role in the synthesis of polyurethanes and of polycarbonates has been described in Chapter 4, and reactions in which polymers are modified by post-treatment with COCl have been described in Chapter 10 (under the Section most appropriate to the type of functional group involved). This Section is mainly concerned with the reactions of phosgene to give novel polymers. 

Probably the simplest polymer formation reaction involving phosgene is that with the dihydric aliphatic alcohols, such as ethylene, propylene or butylene glycol viz. ethane-1,2-diol, propane-1,3-diol or butane-1,4-diol) this reaction results in the formation of linear, wax-like polymers suitable for the impregnation of materials requiring water barrier properties [1133]. 

Phosgene undergoes a condensation reaction with NPhg in the presence of aluminium(III) chloride to form a polymer, m.pt. 189-245 "C, in a yield of 22% [675]. A... 

A resin with mixed carbonic-carboxylic anhydride function has been prepared and used as acylating reagent [144], Thus, the supported chloroformate 140 was obtained by reaction of hydroxymethylated polystyrene with phosgene in benzene (Scheme 7.43). Further treatment with benzoic acid in the presence of triethyl-amine in benzene gave rise to the supported mixed anhydride 141. This polymer has been used in the benzoylation of several amines, although variable amounts of benzoic acid from attack to the internal carbonyl were obtained when using aromatic amines. 

Polycarbonates of numerous bisphenols have been extensively studied. However, most commercial polycarbonates are derived from bisphenol A. At first, both direct-reaction and melt-transesterification processes were employed (Figure 4). In direct-reaction processes, phosgene reacts directly with bisphenol A to produce a polymer in a solution. In transesterification, phosgene is first reacted with phenol to produce diphenyl carbonate, which in turn reacts with bisphenol A to regenerate phenol for recycle and molten, solvent-free polymer. Transesterification is reported to be the least expensive route. It was phased out, however, because of its unsuitability to produce a wide range of products. 

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