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.     

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 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).     

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.     

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.     

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.     

Liquid–crystalline copoly(ester–amide)s prepared from hydroxybenzoic and 4-aminobenzoic acids

Copolycondensations of 3,5-dimethoxy-4-hydroxybenzoic (syringic acid, SGA), 4-hydroxybenzoic(PHB), and 4-aminobenzoic (PAB) acids with diphenyl chlorophosphate(DPCP)/LiCl/pyridine were studied. Random copolycondensations of a wide range of monomer compositions afforded copolymers exhibiting birefringence at room temperature. However, when the sequence of PHB and PAB was fixed by using a newly prepared monomer, 4-(4′-aminobenzoyloxy) benzoic acid (PABBA), the ordered copolymers thus prepared showed birefringence above 200°C, but not at room temperature. Variations in solubility and thermal behavior were also observed in randomly and sequentially prepared copolymers. The monomer sequences in copolymers in random copolycondensations could be changed by controlling the reaction of monomers with DPCP.     

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.     

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.     

Synthesis of soluble aromatic polyesteramides by stepwise copolycondensation of bisphenols and aromatic diamines with diphenyl chlorophosphate in pyridine

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.     

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.     

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 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.     

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.     

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.     

New polymers syntheses. 104. Synthesis of poly(ester‐imide)s from nylon 6, nylon 11, or nylon 12

Nylon 6 was reacted with trimellitic anhydride (TMA) at 230 °C so that a complete degradation to N‐(5‐carboxy‐pentamethylene) trimellitimide was obtained. The crude imide dicarboxylic acid was reacted in situ with 4,4′‐bisacetoxy biphenyl whereby an enantiotropic smectic polyesterimide was obtained. Analogous degradation and polycondensation reactions were also performed with nylon 11 and nylon 12. Parallel syntheses were conducted with isolated imide dicarboxylic acids. Furthermore, the crude imide dicarboxylic acid obtained from nylons 6, 11, and 12 were polycondensed in situ with diacetates of hydroquinone or substituted hydroquinone in combination with various amounts of acetoxy benzoic acid or 6‐acetoxy‐2‐naphthoic acid. In this way enantiotropic nematic copoly(ester‐imide)s were prepared. The phase transition of all LC‐poly(ester‐imide)s were characterized by DSC measurement and optical microscopy. In addition, a series of isotropic poly(ester‐imides)s was prepared using nonmesogenic bisphenols, such as bisphenol A, as comonomers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1630–1638, 2000     

New polymer syntheses XCIII. Hyperbranched homo- and copolyesters derived from gallic acid and β-(4-hydroxyphenyl)-propionic acid

The hyperbranched homopolyester of gallic acid (GA) was prepared by polycondensation of acetylated gallic acid in bulk. Copolyesters of gallic acid and 3-hydroxybenzoic acid (3-HBA) or β-(4-hydroxyphenyl)propionic acid (HPPA) were prepared via the silylated monomers. The degree of branching was varied in both series via the molar fraction of gallic acid. A model reaction with silylated 4-methoxybenzoic acid suggests that all three acetoxy groups of gallic acid can react by ester interchange reactions under the chosen reaction conditions. Furthermore, highly branched copolyesters derived from equimolar ratios of HPPA and 2-, 3-, or 4-hydroxybenzoic acid, vanillic acid, or 4-hydroxycinnamic acid were synthesized. All these copolyesters were found to be amorphous with glass transition temperatures (T_g's) far below that of the hyperbranched poly(gallic acid). © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2347–2357, 1998     

Synthesis and characterization of new thermally stable copoly(ester–amide)s from diester–dicarboxylic acids

Three new aromatic diester–dicarboxylic acids containing furan rings, namely, benzofuro[2,3-b]benzofuran-2,9-dicarboxyl-bis-phenyl ester-4,4^′-dicarboxylic acid, benzofuro[2,3-b]benzofuran-2,9-dicarboxyl-bis-phenyl ester-3,3^′-dicarboxylic acid and benzofuro[2,3-b]benzofuran-2,9-dicarboxyl-bis-naphthyl ester-2,2^′-dicarboxylic acid were synthesized by the reaction of benzofuro[2,3-b]benzofuran-2,9-dicarbonyl chloride with 4-hydroxybenzoic acid, 3-hydroxybenzoic acid and 3-hydroxy-naphthalene-2-carboxylic acid, respectively. Diester–dicarboxylic acids were characterized by FT-IR and NMR spectroscopy and elemental analyses. Then, these monomers were converted to aromatic copoly(ester–amide)s by their reaction with various aromatic diamines via the direct polycondensation. These polymers were characterized by viscosity measurements, solubility tests, FT-IR, Ultraviolet and ¹H-NMR spectroscopy and thermogravimetry. The polymers with inherent viscosities in the range of 0.16–0.37 dl/g in dimethyl sulfoxide at 30 °C were obtained in high yield. Most of them dissolved readily at room temperature in polar solvents. The synthesized copoly(ester–amide)s possessed glass-transition temperatures from 210–255 °C. The copoly(ester–amide)s exhibited excellent thermal stabilities and had 10% weight loss at temperature above 295 °C under nitrogen atmosphere.     

Chiral selectors based on C2-symmetric dicarboxylic acids

Bis-allylamides of rigid C₂-symmetric dicarboxylic acids, useful as precursors in the synthesis of liquid chromatographic chiral stationary phases via hydrosilylation reactions, have been prepared by two different approaches. One involved resolution of the dicarboxylic acid followed by reaction with allylamine via the acid chloride or by a carbodiimide-assisted condensation. The other route involved acetalization of N,N′-diallyl-l-tartardiamide (DATD) with aromatic aldehydes. Moreover, transformation of the enantiopure dicarboxylic acid used in the first route into the corresponding diamine permitted the synthesis of selectors possessing a reversed amide functionality. The enantiomer-discriminating properties of some of these selectors were studied by NMR.     

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.