Preparation of aromatic copolyesteramides by the direct polycondensation with a vilsmeier adduct derived from tosyl chloride and N,N-dimethylformamide

The reaction promoted by Vilsmeier adduct derived from tosyl chloride (TsCl) with N,N-dimethylformamide (DMF) was successfully applied to the preparation of copolyesteramides of high molecular weights directly from aromatic dicarboxylic acids, diamines, and bisphenols. The polycondensation was significantly affected by the reaction of activated dicarboxylic acids with bisphenols and diamines. Addition of a mixture of bisphenols and diamines likely caused gelation of the reaction mixtures, resulting in insoluble polymers, especially with high mol % diamines. Stepweise addition of them, however, gave the homogeneous reaction mixtures and copolymers of better solubility. These phenomena were studied in terms of sequence length distribution of polyester units, which was estimated by thermal analyses of the random copolymers prepared under various conditions for the initial reaction with bisphenols.     

Copoly(amide—ester)s from p-aminobenzoic and hydroxybenzoic acids by the direct polycondensation with diphenyl chlorophosphate and LiCl

The reaction promoted by diphenyl chlorophosphate (DPCP) and LiCl was found to be effectively used for the preparation of aromatic polyesters with high molecular weights directly from hydroxybenzoic acids when the condensing agent was added dropwise. The reaction was successfully to the direct polycondensation reaction of p-aminobenzoic and hydroxybenzoic acids, giving high-molecular-weight copoly(amide—ester)s soluble in amide or phenolic solvents. Copolycondensations of isophthalic and terephthalic acids with bisphenols and aromatic diamines were also examined by adding the DPCP solution to a mixture of these monomers or by initial reaction of DPCP with the acids followed by dropwise addition of a mixture of bisphenols and the diamines. The latter stepwise reaction gave random copolymers soluble in amide and phenolic solvents. Thermal properties of these copolymers were studied.     

Direct polyesterification promoted by a complex of diphenyl chlorophosphate with LiBr

The diphenyl chlorophosphate (DPCP)-promoted polycondensation reaction between aromatic dicarboxylic acids and bisphenols was largely improved by carrying out the reaction in the presence of lithium halides to give high molecular weight aromatic polyesters. Among the halides LiBr, which is capable of forming a complex with hexamethylphosphoramide, was most effective, suggesting that a similar complexation of DPCP with LiBr in pyridine facilitates the complete reaction of DPCP with carboxyl groups. The complex could selectively activate carboxyl groups of hydroxybenzoic acids to give high molecular weight copolyesters from several combinations of aromatic hydroxy acids. The reaction could also be adaptable to the copolycondensations of a mixture of the dicarboxylic acids, bisphenols, and hydroxybenzoic acids.     

Preparation of aromatic polyesters by the direct polycondensation reaction with diphenyl chlorophosphate in pyridine

The direct polycondensation reaction of diphenyl chlorophosphate (DPCP) as a new condensing agent in pyridine was used for the preparation of polyarylene esters. High-molecular-weight polymers can be prepared by reacting a pyridine solution of dicarboxylic acids and DPCP in the presence of LiCl, followed by treating with a pyridine solution of bisphenols. About an equivalent of LiCl, and 30 mol % excess of DPCP were most favorably added. Effects of the initial reaction of the acids and DPCP, and of dropwise addition of bisphenols on the polycondensation were investigated. Polycondensations of several hydroxybenzoic acids were also carried out with limited success.     

Direct polycondensation with tosyl chloride in pyridine by formamide catalyzed alcoholysis

The reaction with tosyl chloride was significantly promoted by controlling alcoholysis with bisphenols in the presence of catalytic amounts of formamides to give aromatic polyesters with high molecular weights from aromatic dicarboxylic acids and bisphenols. Mechanistic features of the reaction were studied by use of various formamides and other arylsulfonyl chlorides, as well as by varying the addition mode of bisphenols and changing the relative amount of formamide. The reaction was successfully applied to the preparation of aromatic polyesteramides with high molecular weights from aromatic dicarboxylic acids, bisphenols, and diamines, but with limited success to that of polyamides.     

Thermotropic liquid crystallinity of copoly(ester-amides) prepared by the direct polycondensation with diphenyl chlorophosphate in pyridine

Copolycondensation of isophthalic (IPA) and terephthalic (TPA) acids, methylhydroquinone (MeHQ), and aromatic diamines with diphenyl chlorophosphate (DPCP) in pyridine were investigated. The resulting copoly(ester-amides) showed optical anisotropy, which was discussed in terms of the ester and amide sequence lengths in the copolymers. The temperature above which the anisotropy was observed varied in the 225 to 300°C range by changing addition time of a mixture of MeHQ and diamines, initial reaction with MeHQ, and the further reaction with diamines.     

Direct polycondensations of hydroxybenzoic acids by use of diphenyl chlorophosphate in the presence of N,N-dimethylformamide

Direct polycondensation reaction of hydroxybenzoic acids with diphenyl chlorophosphate (DPCP) in pyridine was largely improved by carrying out the reaction in the presence of a formamide. Among the formamides examined, N,N-dimethylformamide (DMF), N,N-dimethylformamide, and N,N-dimethylacetamide were favorably used. A Vilsmeier adduct thus derived from DPCP and DMF was very effective especially for the preparation of high-molecularweight copolyesters from hydroxybenzoic acids. Copolymers of several combinations of hydroxybenzoic acids were prepared and their solubility and thermal properties were investigated. The polycondensations of aromatic dicarboxylic acids and bisphenols with the adduct were also studied.     

Direct polyesterification with thionyl chloride in pyridine improved by a modification of monomer sequences in copolymers

The direct polyesterification with thionyl chloride (SOCl₂) in pyridine was further investigated. Copolycondensations of dicarboxylic acids, bisphenols, and hydroxybenzoic acids were significantly affected by the reaction temperatures and combinations of monomers which could change relative rates of alcoholyses of the activated dicarboxylic acids and the hydroxyacids consequently to vary monomer sequences in the copolymers resulted. The sequences were tried to be varied more directly by stepwise reactions of monomers in copolycondensations of dicarboxylic acids, bisphenols, and p-hydroxybenzoic acid (PHB), as well as PHB and m-hydroxybenzoic acid (MHB). The reactions proceeded smoothly and satisfactorily when carried out by initial reaction of dicarboxylic acids and PHB followed by bisphenols likely to favor sequential to random distributions of monomers. Reverse addition of PHB and bisphenols, and then dicarboxylic acids resulted in rapid precipitation due to some oligomerization of PHB at an earlier stage of reaction, and largely retarded the reaction. This was also the case for the copolycondensation of PHB and MHB. Copolymers of high inherent viscosities with up to 65 mol % PHB could be obtained by initial reaction of MHB followed by PHB.     

Polyesterification of aromatic dicarboxylic acids and bisphenols with tosyl chloride/dimethylformamide/pyridine promoted by the improvement of the difficult solubility of the activated diacids with lithium chloride

The solution polyesterification of dicarboxylic acids in pyridine, the activated intermediates of which were difficult to dissolve in tosyl chloride/dimethylformamide/pyridine, was investigated in the presence of lithium chloride. The solubility of the activated dicarboxylic acids was largely improved by the presence of the salt, and the polycondensation with bisphenols was greatly facilitated. The salt was more effectively added to a pyridine solution of dicarboxylic acids than to the activated dicarboxylic acids in pyridine. The favorable additive effect on the improved solubility was attributed to a lowered degree of association of the activated dicarboxylic acids, which led to distributions of the resulting oligomers from bisphenols at an earlier stage closer to the theoretical ones and yielded better polycondensation results. The reaction, which proceeded through favorable distributions of the co‐oligomers, produced copolymers of higher inherent viscosities and slightly block sequence distributions determined by NMR. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2725–2733, 2004     

Direct polycondensation of aromatic dicarboxylic acids and bisphenols with tosyl chloride and N,N-dimethylformamide in pyridine

A Vilsmeier adduct derived from arylsulfonyl chlorides and DMF in pyridine was successfully used as a new condensating agent for the synthesis of aromatic polyesters by the direct polycondensation of aromatic dicarboxylic acids and bisphenols and also of hydroxybenzoic acids. Polymers of high molecular weights (M?_w = 78,000) with relatively narrow molecular weight distribution (M?_w/M?_n ≈ 3.0) were prepared by reacting aromatic dicarboxylic acids with the adduct in pyridine, followed by addition of bisphenols. The polycondensation was significantly affected by the amount of DMF, the nature of the arylsulfonyl chlorides, the conditions of initial reaction of the acids with the adduct, and the rate of reaction with bisphenols. The process was adaptable to the direct polycondensation of hydroxybenzoic acids, affording polymers of high molecular weight (η_inh = 1.73).     

Polyheteroarenes based on aromatic imidoyl chlorides

Interaction of imidoyl chlorides with various diamines, bisphenols, and dicarboxylic acids was studied.     

Aromatic copolyesteramides by the direct polycondensation with diphenyl chlorophosphate and carboxamides in pyridine

The reaction promoted by a Vilsmeier adduct derived from diphenyl chlorophosphate and N,N-dialkylcarboxamides such as N,N-dimethylformamide was successfully used for the preparation of soluble copolyesteramides directly from aromatic dicarboxylic acids, bisphenols, and a wide range of mole percent diamines. The polycondensation was affected by the carboxamides used, and an attempt was made to explain the effect by the ester sequence in polyamide units by examining a competitive reaction of benzoic acid with a phenol and an aniline and by examining the thermal properties of the copolymers produced.     

Direct polyesterification promoted by a complex of phosphorus oxychloride with LiCl monohydrate

The reaction of benzoic acid and p-chlorophenol with phosphorus oxychloride (POC) was significantly affected by the presence of metal salt hydrates or a mixture of metal salts and water sufficiently aged. Among metal salts examined, LiCl was most effective for the reaction to give quantitative yield of the benzoate. The reaction was assumed to proceed via a complexation of POC with LiCl monohydrate followed by selective hydrolysis of POC by water bound to LiCl. The reaction promoted by a complex derived from POC and LiCl monohydrate in pyridine was successfully used as a new condensing agent for the synthesis of aromatic polyesters by the direct polycondensation or aromatic dicarboxylic acids and bisphenols. Under favorable conditions for aging of POC with LiCl monohydrate and for addition of bisphenols, polymers of moderate to high molecular weights were obtained in quantitative yield. The reaction was applied with limited success to the preparation of a copolymer of high molecular weight from hydroxybenzoic acids.     

Direct polyesterification with thionyl chloride in pyridine improved by a modification of monomer sequences in copolymers

The direct polyesterification with thionyl chloride (SOCl₂) in pyridine was further investigated. Copolycondensations of dicarboxylic acids, bisphenols, and hydroxybenzoic acids were significantly affected by the reaction temperatures and combinations of monomers which could change relative rates of alcoholyses of the activated dicarboxylic acids and the hydroxyacids consequently to vary monomer sequences in the copolymers resulted. The sequences were tried to be varied more directly by stepwise reactions of monomers in copolycondensations of dicarboxylic acids, bisphenols, and p-hydroxybenzoic acid (PHB), as well as PHB and m-hydroxybenzoic acid (MHB). The reactions proceeded smoothly and satisfactorily when carried out by initial reaction of dicarboxylic acids and PHB followed by bisphenols likely to favor sequential to random distributions of monomers. Reverse addition of PHB and bisphenols, and then dicarboxylic acids resulted in rapid precipitation due to some oligomerization of PHB at an earlier stage of reaction, and largely retarded the reaction. This was also the case for the copolycondensation of PHB and MHB. Copolymers of high inherent viscosities with up to 65 mol% PHB could be obtained by initial reaction of MHB followed by PHB.     

Direct synthesis of aromatic polyesters by use of a sulfonium salt derived from tosyl chloride and N-methylimidazole

A sulfonium salt derived from tosyl chloride and N-methylimidazole was successfully used as an effective condensing agent for the preparation of high-molecular-weight aromatic polyesters by the direct polycondensation of aromatic dicarboxylic acids and bisphenols. Conditions for the formation of the sulfonium salt and of the reaction of the salt with dicarboxylic acids favorable for the polycondensation were examined. Thermal property of a polymer was investigated in terms of random sequences of monomer in the polymer backbone. Preparation of a polyamide and a polyesteramide was attempted with limited success.     

Preparation and properties of aromatic copolyamides from aromatic diisocyanates and aromatic dicarboxylic acids

Wholly aromatic random copolyamides of high molecular weights were prepared by the high-temperature solution polycondensation of an aromatic diisocyanate, 4,4′-methylenedi(phenyl isocyanate) or 2,4-tolylene diisocyanate, with a mixture of isophthalic acid and 4,4′-oxydibenzoic acid. Glass transition temperatures of the polyamides and copolyamides were between 229 and 273°C; this depended on the combination of diisocyanates and dicarboxylic acids used. These aromatic copolyamides showed better solubility in various organic solvents and reduced crystallinity, compared to the corresponding homopolyamides. The copolyamides prepared from 2,4-tolylene diisocyanate had greater solubility and higher glass transition temperatures than those obtained from 4,4′-methylenedi(phenyl isocyanate).     

Preparation of polyaryl esters by a new direct polycondensation reaction with arylsulfonyl chlorides in pyridine

Arylsulfonyl chlorides were successfully used as a new condensing agent for the synthesis of polyaryl esters by the direct polycondensation of aromatic dicarboxylic acids and bisphenols. High-molecular-weight polymers (M_w = 84,000) were prepared by reacting dicarboxylic acids with the sulfonyl chlorides in pyridine in the presence of LiCI, followed by treating with a pyridine solution of bisphenols. The polycondensation was significantly affected by factors, such as, the kind of arylsulfonyl chlorides, its amount, the conditions of initial reaction of the acids with the sulfonyl chlorides, the amounts of LiCI added, and dropwise addition of bisphenols.     

Direct polycondensation of hydroxybenzoic acids with thionyl chloride in pyridine

The reaction promoted by thionyl chloride and pyridine could selectively activate carboxyl groups of hydroxybenzoic acids to give polyesters of high inherent viscosities up to 3.8. Favorable conditions were studied in terms of the temperatures for the initial reaction with the acids and subsequent aging at room temperature. Copolymers of several combinations of hydroxybenzoic acids with high molecular weights were obtained in quantitative yield by carrying out the polycondensation at 80°C for 3 h. The reaction could also produce high molecular polyesters in a simpler process without the initial activation of dicarboxylic acids by adding a mixture of these monomers to the condensing agent, and a tough film- and fiberforming polymer was obtained from 4,4′-dihydroxyphenylsulfone of low nucleophilicity whose polymer of high molecular weight is difficult to obtain. The process was also successfully applied to the direct copolycondensations of hydroxybenzoic acids, aromatic dicarboxylic acids, and bisphenols to produce polyesters of η_inh up to 5.6.     

Synthesis of aromatic polyesters by direct polycondensation with triphenylphosphine dichloride

Aromatic polyesters of high molecular weights were prepared by the direct polycondensation reaction of dicarboxylic acids and bisphenols or hydroxybenzoic acids with triphenylphosphine dichloride as a new condensing agent. Reaction conditions, including the amount of reagents and the concentration of monomer, solvent, and acid acceptor, were investigated. The aromatic polyester with the solution viscosity of 1.66 dL/g was obtained from bisphenol. A and terephthalic and isophthalic acid in quantitative yield under the optimum condition. The principal advantage of this condensing agent is that, based on the recycling system, recovered triphenylphosphine oxide can be reconverted to the reactive triphenylphosphine dichloride by treating with phosgene or oxalyl chloride.     

Preparation of aromatic polyesters by direct polycondensation with thionyl chloride in pyridine

Mechanistic features of the reaction with thionyl chloride in pyridine were studied in a model reaction of benzoic acid with p-chlorophenol or aniline. The yields were significantly affected by the amounts of pyridine, favorably by four equivalents, and the nature of pyridine, suggesting that pyridines are not only HCl scavengers, but are also involved in the reaction itself. The reaction was assumed to proceed via a carboxylic sulfinic-anhydride intermediate different from acyl chloride, and the intermediate was found to be not so reactive that it was completely alcoholyzed by the phenol at high temperatures of more than 60°C. The reaction was successfully applied to the preparation of aromatic polyesters of high molecular weights by the direct polycondensation of aromatic dicarboxylic acids and bisphenols in pyridine at 80°C.