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The solution polycondensation of a mixture of various parts of isophthalic acid (IPA) and terephthalic acid (TPA) with 4,4′-dihydroxydiphenylsulfone (BPS) with tosyl chloride/dimethylformamide/pyridine as a condensing agent was studied. To elucidate how the reaction should be done to obtain copolymers of high molecular weights, we examined the two-stage copolycondensation with BPS and 2,2-bis(4-hydroxyphenyl)propanes (BPAs) by changing the content of IPA/TPA and the amount of BPS or BPA used in the initial reaction. Controlling the reaction at an earlier stage could facilitate the copolycondensation. The polyesters of IPA/TPA and BPS of moderate inherent viscosity values up to 1.0 were obtained by the two-stage reaction with optimal amounts of BPS first and then additional BPS. Satisfactory results were also obtained by the dropwise addition of BPS over 10–20 min in the preparation of the IPA/TPA–BPS polymers containing less than 50 mol % TPA. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2607–2610, 2002

A new condensing agent comprised of tosyl chloride (TsCl) and N-piperidinoformamide (NPF) in pyridine was very effective for the preparation of polyesters of aromatic dicarboxylic acids and aliphatic and aromatic diols with the highest molecular weight reported to date obtained by the solution reaction. The reaction yielded the most favorable results using about 0.3 equivalents of NPF with respect to the carboxyl groups and by dropwise addition of the diols over a period of about 20 min.

The polyesterification of a mixture of equal parts of isophthalic and terephthalic acids with 2,4-dihydroxybenzophenone (2,4-DHBP) and several dihydroxyacetophenones (DHAPs), from which polyesters of high molecular weight have not been prepared, was studied. Based on favorable results of two-stage copolycondensation with bisphenols first and then with 2,4-DHBP, factors such as dropwise addition of DHAPs, mol-% of them used in the initial stage, and the temperature in the subsequent stage were examined in a two-stage polycondensation, Favorable results were obtained by longer period of addition, initial reaction of 50-70 mol-%, and low temperature to 60 °C. The relationship between the temperature and the distribution of resulting oligomers determined by GPC was also examined. The copolymers obtained exhibited the glass transition temperatures and polymer melting points in the ranges of 165-183°C and of 280-310°C, respectively. Most of them were soluble in DMF, chloroform, cyclohexanone, and THF.

The reaction of sterically hindered hydroxyl groups at the 2-position of methylhydroquinone and phenylhydroquinone (PhHQ) to form esters was largely promoted by their slow addition to benzoic acid activated by diphenyl chlorophosphate in pyridine. A modification of this reaction was applied to the preparation of thermotropic terephthalic acid/PhHQ and 2,5-dichloroterephthalic acid/PhHQ polymers with randomly oriented phenyl substituents, and the properties of the polymers were studied in terms of their transition temperatures, which were determined by differential scanning calorimetry and microscopic observation. The melting points were lowered by about 30–50 °C by the dropwise addition of PhHQ over 10–30 min. The molecular structures of the 2,5-dichloroterephthalic acid/PhHQ polymers were studied by 13C NMR. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1726–1732, 2001

Copolycondensations of IPA, TPA, bisphenol A (BPA), and several cimonomers were carried out to improve thermal properties, such as, the glass transition temperature (Tg) of the IPA/TPA (50/50)–BPA polyester. Among the comonomers examined, 4,4′-Dihydroxydiphenylsulfone (BPS) and 4,4′-Dicarboxydiphenylsulfone (DCDPS) having a strongly dipolar sulfonyl group in the chain were significantly effective. The favorable effect upon the Tgs was studied by varying the amounts of BPS and DCDPS incorporated into the copolymers. In the copolycondensation with BPS, two-stage copolycondensation of BPA first and then BPS, the reverse order of reaction, and their spontaneous addition were examined to investigate the effect of distribution of the BPS unit segments in the copolymer upon the Tgs of the resulted copolymers. The distribution was briefly studied from distribution of the IPA/TPA-BPA oligomers in the initial reaction using GPC. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 875–879, 2000

Dihydroxybenzophenones and 4,4'-dihydroxydiphenylsulfone, which yield high-molecular-weight polyesters only difficultly by conventional methods, gave high-molecular-weight copolyesters through a two-stage copolycondensation involving initial induction of oligomerization with selected monomers followed by copolycondensation. The copolycondensation was studied by examining such factors as the kinds of initial monomers, their amounts, initial reaction times, and the order of reaction, and the results are explained in terms of oligomer distribution in the initial oligomerization as determined by GPC. Copolycondensation was also facilitated by lowering the temperature at the second stage of reaction.

Copolycondensations of IPA, TPA, BPA, and PHB were studied to investigate how PHB, which can form mesogenic segments, should be incorporated into the amorphous IPA/TPA–BPA polyester to obtain the thermotropic copolyester, unlike other copolymerizations studied so far by randomly introducing nonmesogenic components into the liquid crystalline polyesters. Random and controlled copolycondensations were attempted to regulate the segment length of mesogenic PHB units by stepwise addition of BPA and PHB through the two- and three-stage reactions using TsCl/DMF/Py as a condensing agent. Thermotropic copolyesters with ca. 40 mol % PHB could be obtained by a three-stage reaction, despite that more than 70 mol % PHB is needed to prepare by usual random copolymerization with PHB. The segment length of the PHB unit was indirectly studied from IPA/TPA–BPA oligomer distribution at initial reaction by means of GPC and from the NMR analysis of the resulting copolymers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2371–2377, 1999

Copolycondensations of TPA, PhHQ, and several aromatic diacid and diol modifiers were examined for which kind of the modifiers incorporated is more effective to reduce the transition temperatures of the resulting copolyesters and how they affect the temperatures. The acid modifiers are more effective than the diol ones, significantly when they have substituents. As another type of modifier, HBA forming the ester bond of an AB structure different from the AABB structure of TPA/PhHQ polyester was also effective, and the lowering effect on the temperatures was varied by the mode of copolycondensations, being most remarkable when HBA was randomly introduced. The results obtained were discussed in terms of the disturbance and thereby weakening of the interchain dipole–dipole interaction between the carbonyl groups in the ester linkages due to the introduction of the diacid modifiers and of HBA having an ester bond of a different directionality. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 621–626, 1999

The reaction of the N-phosphonium salt of pyridine derived from phosphorus oxychloride in pyridine was successfully used for the preparation of aromatic polyesters with high molecular weight when carried out in the presence of lithium chloride. In the copolycondensations of isophthalic and terephthalic acid with diphenols, the mode of reaction with the diacids was expected to produce several types of the diacid activated intermediates, which might control the sequences of the diacids in the copolymers. The possible variation of the sequences was studied in terms of the mode and copolymer properties such as glass transition temperatures and liquid crystalline transition temperatures. Competitive model reactions were carried out to discuss these relationships. © 1993 John Wiley & Sons, Inc.

A new condensing agent comprised of tosyl chloride (TsCl) and triphenylphosphine oxide (TPPO) in pyridine was very effective for the preparation of polyesters of aromatic dicarboxylic acids and bisphenols with higher molecular weight than those obtained from TsCl/dimethylformamide in pyridine. Among the phosphorus compounds examined TPPO was most effective, and the reaction using half an equivalent with respect to the carboxyl groups yielded the most favorable results at temperatures of more than 100°C.

High-viscosity polyesters can be prepared by the polycondensation of secondary aliphatic trans-cyclohexanedicarboxylic acid (t-CHDC) and hydroquinones using SOCl 2 /pyridine condensing agent at 80°C. Incorporation of its cis-isomer significantly affected η inh and the thermal property of the resulting copolymers. The copolymers of t-CHDC, hydroquinones, and p-hydroxybenzoic acid having different monomer sequences were prepared by changing the order of introduction of monomers.

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.

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 (Mw = 78,000) with relatively narrow molecular weight distribution (Mw/Mn ≈ 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 (ηinh = 1.73).

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.

The reaction promoted by diphenyl chlorophosphate (DPCP) in pyridine was successfully applied to the preparation of soluble aromatic copolyesteramides of high molecular weights directly from aromatic dicarboxylic acids, bisphenols, and a wide range of mol % aromatic diamines. Dropwise addition of a mixture of bisphenols and diamines (more favorably of bisphenols and then diamines) to the mixture of dicarboxylic acids activated by DPCP led the reactions homogeneously even with high mol % of diamines to produce copolymers of good solubility. This improved copolymer solubility was roughly estimated by sequence distribution of polyamide and polyester units in the copolymers, which was studied in a model reaction and in the copolycondensations by simultaneous and stepwise addition of bisphenols and diamines.

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.

In order to preprare polyamides and polyesters with high molecular weights, the reactions of dicarboxylic acids with diamines, and with diols should take place almost quantitatively, This article describes how phosphorus and sulfur intermediates have been developed to activate carboxyl groups effectively and efficiently enough to lead the reactions completely.

Polyaryl esters of moderate molecular weights were prepared by the direct polycondensation reaction of hydroxybenzoic acids and its derivatives with hexachlorocyclotriphosphatriazene (also known as phosphonitrilic chloride trimer, PNC) as a condensing agent in pyridine. Copolymerization of p-hydroxybenzoic acid with several hydroxybenzic acid derivatives was carried out to improve the processability of the polymer of p-hydroxybenzoic acid, which yields fusible and soluble copolymers of high inherent viscosities. Polymer solubility and thermal behavior were examined.

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.

This atricle is concerned with the reactions of the phosphonium salts derived from the oxidation of phosphites and from nonoxidative cleavage of the P-O- (C) bonds facilitated by tertiary amines and metal salts, and with their application to polymer syntheses by the direct polycondensations of dicarboxylic acids and diamines, of free amino acids, and of carbon dioxide and diamines. Initiation and propagation in the polycondensation and their significant effects on the molecular weight of the resulting polymers are discussed. The preparation of polyesters by use of phosphorus chlorides is also described.