Nitrobenzene polycondensation

Triazine containing polysulfides having high molecular weights have been readily synthesized by the phase-transfer catalyzed polycondensation of 6-diethylamino or dibutylamino-l,3,5-triazine-2,4-dithiols with 1,10-dibromodecane in the presence of cetyl trimethyl ammonium bromide in a nitrobenzene-aqueous alkaline solution system <99MI294>. 

When the polycondensation process was carried out in organic solvents (nitrobenzene, NMP, and m-cresol) at 180-210 C and an effective catalyst (benzoic acid) was used, PNI having high viscosity characteristics and exhibiting film-forming properties were synthesised [3-36]. 

The actual formation of hyperbranched material proceeds during the polymerization of 3,5-difluoro-4 -hydroxydiphenyl sulfone in the presence of 3,4,5-trifluorophenylsulfonyl benzene or tris(3,4,5-trifluorophenyl)phos-phine oxide as a core molecule. Cyclic oUgomers formed dining this polymerization contribute to a low-molecular-weight polymer ranging from 3400 to 8400 Dalton. A triazin-based AB2 monomer has also been described. This monomer is shown in Figure 7.8. A hyperbranched aromatic poly(ether sulfone) with sulfonyl chloride terminal groups has been prepared by the polycondensation of 4,4 -(m-phenylenedioxy)-bis-(benz-enesulfonyl chloride). The polymerization was carried out in nitrobenzene at 120°C for 3 h in the presence of a catalytic amount of FeCls. ... 

In work [62] it has been shown, that temperature synthesis T increasing at high-temperature polycondensation of polyaiylates, obtained by interaction of diphenols of different chemical stracture with dianhydride of terephthalic acid, results to reaction rate constant growth (the value pj was used for polycondensation first stage up to conversion degree Q 0.30-0.50). The solvent nature, in solution of which synthesis was performed, influences perceptibly on value. So, the value - pj is higher at polycondensation in nitrobenzene enviromnent, than in diphenyloxide enviromnent. The systematic enhancement was found... 

The authors [118, 119] fulfilled description of the low-temperature polycondensation process of polyaiylate Ph-2 in 8 different solvents (N,N-di-meth-ylformamide, nitrobenzene, acetone, 1,2-dichloroethane, chloroform, 1,2,4-tri-chlorobenzene, benzene and 1,4-dioxane) within the framewoiks of irreversible aggregation cluster-cluster model [120]. 

The polyarylesterketones can be produced by means of interaction between bisphenylsulfide, dibenzo rane and bisphenyloxide with monomers of electrophylic nature (phosgene, terephthaloylchloride) or using homopolycondensation of 4-phenoxybenzoylchloride and 4-phenoxy-4-chlorcarbonyl-bisphenyl in the presence of dichloroethane at 25 °C [282-285], Aromatic polyesterketones form after the polycondensation of 4-phenoxybenzoylchloride with chloranhydrides of tere- and isophthalic acids, 4,4 -dicarboxybisphenyloxide in the environment of nitrobenzene, methylchloride and dichloroethane at temperatures from -70 till 40 °C during 16-26 h according Friedel-Crafts reaction. 

The effect of organic solvent on the two-phase polycondensation is shown in Table 13.3.15. Chloroform, 1,2-dichloroethane, nitrobenzene, acetophenone and anisole were all effeetive as the polymerization media to produce moderate moleeular weight polymer... 

There is, however, an Important practical difference between the reaction conditions required for successful operation of the routes to polyetherketones as compared with those for the polysulphones and this arises from a crucial difference between the two classes of polymers. Polyethersulphones are amorphous or only slightly crystalline and dissolve readily in polar organic solvents such as nitrobenzene or dimethyl sulphoxide at room temperature, but many polyetherketones develop considerable crystallinity and dissolve only at temperatures close to their melting points in this type of solvent. The insolubility of these polymers presented a major synthetic problan as it limits the molecular weights that could be obtained before the growing chains crystallised out from the polycondensation system and this is the main reason why commercial development of the polyetherketones lagged behind that of the polyethersulphones Solutions to this problem for the polyaroylation reactions, (1), were found first by du Pont and then by Raychem, while for the polyether syntheses the problem was solved by ICl. Raychem manufactured a polymer of structure 1, named Stilan, between 1972 and 1976, and manufacture of the ICI polymer, II, trade name Victrex PEEK", started in 1982. 

The one-step polycondensation in nitrobenzene was less sensitive to the stoichiometry of reagents than the two-step synthesis.PAtss] PT-IR spectra of the obtained Pis showed intensive characteristic imide bands at 1773 cm (imide C=0 asymmetrical stretching), 1714 cm (imide C=0 S3nnmetrical stretching), and 1380 cm (imide CNC axial), confirming the complete imidization. 

The effect of solvents on the two-phase polycondensation is shown in Table 8. Chlorinated hydrocarbons such as dichloromethaue, chlorofom, and 1,2-dichloroethane, and aromatic solvents like benzene and nitrobenzene were used favorably to yield polysulfide XXm with inherent viscosities of 0.3-0.7 dL/g. 

In the preparation of the linear analogues, solvents such as nitrobenzene [478] and methylene chloride [479] were used. A new method capable of creating poly(ether ketone) and polyfthioether ketone) was recently disclosed by Ueda et al. [480-482]. Here, the dehydrating power of a mixture of phosphorus pentoxide and methanesulfonic acid (MSA) is the driving force for the direct polycondensation of aromatic dicarboxylic acids with aryl compounds contain-... 

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