Studies in the quinoxaline series. 17. Preparation and properties of some derivatives of 2-sulfonylmethylquinoxaline

Ketimines of 2-methylthiomethyl- and 2-methylsulfonylmethyl-3-oxodihydroquinoxaline have been prepared with the object of studying their tautomeric forms. The enaminoester of 1,3-bis(ethoxycarbonyl)-4,9-dihydrothienol[3,4-b]-quinoxaline-2,2-dioxide is very stable: it does not eliminate sulfur dioxide on boiling in diphenyl ether, under UV irradiation, or under electron bombardment. Reductive decomposition does not lead to the expected dienaminoester.For communication 16, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 352–355, March, 1987.     

Preparation and properties of aniline chain-extended thermoplastic epoxy resin using triphenylphosphine as catalyst

Thermoplastic resins have been widely used in fiber reinforced polymer composites because of its recyclability and short cycle times. However, the high viscosity after heating and melting restricts its infiltration on the surface of fiber. In this study, a series of thermoplastic epoxy resins were prepared via the chain extension reaction of epoxy groups with liquid aniline using triphenylphosphine (TPP) as catalyst. The relationship between polymer network structure and performance was comprehensively investigated. The solubility tests indicated that excessive aniline or TPP facilitated the crosslinking of resins. Besides, on the premise of thermoplasticity, appropriate TPP could increase the degree of chain extension, molecular weight, and glass transition temperature of resins. Furthermore, the in-situ polymerization process facilitated infiltration between epoxy resin and the fibers before chain extension reaction. The bending test showed that the flexural performance of the sample with 2 phr of TPP was improved by 38.8%. Therefore, this work provides a feasible method to prepare the thermoplastic epoxy resins and its fiber-reinforced composites with good mechanical properties.     

Telechelic sulfate ionomers. I. Preparation and solution and thermal properties

New telechelic ionomers with zinc and sodium sulfate salt terminal groups on hydrogenated polybutadiene (HPB) backbones ( I ) were prepared from hydroxyl-terminated hydrogenated polybutadiene (HTHPB) of three different molecular weights (1350, 2100, and 3200 g/mol). Quantitative acid-base titration, elemental analysis, and NMR spectroscopy were used to verify the structure, and further characterization included differential scanning calorimetry (DSC) and solution viscometry. The DSC results indicated that the ionomers are free of impurities within the limit of the resolution of the method. Glass transition temperatures determined by DSC indicated that the elevation in glass transition temperature by ionic crosslinking was most strongly dependent on the molecular weight of the backbone of the telechelic ionomer. The solution viscometry results showed that the sulfation reaction did not cause either covalent crosslinking or chain scission. Furthermore, the solubility characteristics of the sulfate-terminated hydrogenated polybutadiene (STHPB) oligomers were shifted towards a preference for polar solvents by the presence of salt groups. The lower molecular weight ionomers of the series showed polyelectrolyte-like extension at very dilute concentrations in polar solvents. The onset of polymer gelation in hexane was observed for the ionomers which had the highest molecular weight backbones.     

Studies on the thermotropic liquid crystalline polymer. I. Synthesis and properties of polyamide-azomethine-ether

A series of polyamide-azomethine-ethers was prepared by condensation of 4,4′-diaminoanilide with 4,4′-diformyl-α,ω-diphenoxyalkane, 4,4′-diformyl-3,3′-methoxy-α,ω-diphenoxyalkane, and 4,4′-diformyl-3,3′-ethoxy-α,ω-diphenoxyalkane, respectively. The inherent viscosities of polymers were obviously increased when the polymers were treated by heat under nitrogen at 220°C. The thermotropic liquid crystalline properties were examined by DSC, microscope observations, and TGA. All of the polymers, except polymer A-1, exhibit thermotropic liquid crystalline properties. They also exhibit threaded and/or Schlieren textures examined by the polarizing microscope which indicate a nematic phase. In most cases, the mesophase exists up to ca. 400-460°C shown by TGA study. The mesophase cannot exist above 400-460°C because of the thermal decomposition.     

Studies on antiinflammatory agents. I. Synthesis and pharmacological properties of 2'-phenoxymethanesulfonanilide derivatives.

Various 2'-phenoxymethanesulfonanilide derivatives were synthesized and evaluated for antiinflammatory and analgesic activities. Some compounds bearing an electron-attracting substituent at the 4'-position strongly inhibited adjuvant-induced arthritis in rats and acetic acid-induced writhing syndrome in mice without causing gastro-intestinal irritation. Among them, 4'-cyano-(FK867) and 4'-acetyl-(FK3311) 2'-(2,4-difluorophenoxy)methanesulfonanilides were selected as the candidates for further development.     

Liquid crystal polymers. I. Preparation and properties of p-hydroxybenzoic acid copolyesters

High molecular weight copolyesters were prepared by the acidolysis of poly(ethylene terephthalate) with p-acetoxybenzoic acid and polycondensation through the acetate and carboxyl groups. The mechanical properties of the injection-molded copolyesters containing 40–90 mole- % p-hydroxybenzoic acid (PHB) were highly anisotropic and dependent upon the PHB content, polyester molecular weight, injection-molding temperature, and specimen thickness. As the injection-molding temperature increased and the specimen thickness decreased, the tensile strength, stiffness, and Izod impact strength increased when measured along the direction of flow of the polymer melt, and the coefficient of thermal expansion was zero. In some compositions these properties were superior to those of commercial glass fiber reinforced polyesters. Maximum tensile strengths, flexural moduli, notched Izod impact strengths, and minimum melt viscosities were obtained with polyesters containing 60–70 mole-% PHB. Higher oxygen indicies (39-40) and heat deflection temperatures (150-220°C) were obtained with 80–90 mole-% PHB.     

Liquid crystal polymers. I. Preparation and properties of p-hydroxybenzoic acid copolyesters

High molecular weight copolyesters were prepared by the acidolysis of poly(ethylene terephthalate) with p-acetoxybenzoic acid and polycondensation through the acetate and carboxyl groups. The mechanical properties of the injection-molded copolyesters containing 40–90 mole-% p-hydroxybenzoic acid (PHB) were highly anisotropic and dependent upon the PHB content, polyester molecular weight, injection-molding temperature, and specimen thickness. As the injection-molding temperature increased and the specimen thickness decreased, the tensile strength, stiffness, and Izod impact strength increased when measured along the direction of flow of the polymer melt, and the coefficient of thermal expansion was zero. In some compositions these properties were superior to those of commercial glass fiber reinforced polyesters. Maximum tensile strengths, flexural moduli, notched Izod impact strengths, and minimum melt viscosities were obtained with polyesters containing 60–70 mole-% PHB. Higher oxygen indicies (39–40) and heat deflection temperatures (150–220°C) were obtained with 80–90 mole-% PHB.     

The influence of heteroaromatic rings on mesomorphic properties I. A new series of pyridazine- and pyridine-carboxylates

We have prepared new esters of 6-alkyloxypyridazine-3-carboxylic acid and the 6-alkyloxypyridine-3-carboxylic acid. The introduction of the heteroaromatic rings leads to significant changes in mesomorphic behaviour. The compounds exhibit a strong tendency to form smectic C phases.     

Studies on halogen derivatives of phenylazochromotropic acid: I. The acid-base properties

The acid-base properties of six halogen derivatives of phenylazochromotropic acid have been studied in an attempt to apply them as metallochromic or chromophoric indicators. The absorption spectra are studied in buffer solutions of varying pH values. The variation of spectra with pH indicates the presence of two equilibria between H₂D^2?, HD^3? and D^4? species. The pK values of the naphthlenic OH groups are determined spectrophotometrically and are discussed in relation to molecular structure while those of the sulfonic acid groups are determined potentiometrically.