Colorimetrie, Photometrie

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Synthesis of aromatic polythioamide-oxothioxoquinazolines from bis(1,3,4-thiadiazoline-5-thione) and aromatic bis-o-amino esters

Aromatic polythioamide-oxothioxoquinazolines were synthesized by the polycondensation of 2,2′-(m-phenylene)bis-1,3,4-thiadiazoline-5-thione with aromatic bis-o-amino esters. The polymerizations were carried out at 160°C in acidic media such as m-cresol, sulfolane, and polyphosphoric acid to produce polymers with reduced viscosities up to 0.5 dL/g. These polymers were soluble in polar aprotic solvents like N-methyl-2-pyrrolidone and some acidic media including m-cresol. The polythioamide-oxothioxoquinazolines showed relatively good thermal stability with 10% weight loss at 344–394°C in air.     

Preparation and properties of high transition temperature aromatic polyphosphonates by phase-transfer-catalyzed polycondensation of phenylphosphonic dichloride with bisphenols

Aromatic polyphosphonates of high molecular weights were prepared from phenylphosphonic dichloride and bisphenols having rigid ring structures by the two-phase polycondensation in organic solvent–aqueous alkaline solution system with phase-transfer catalyst at 0°C or below. The effects of reaction solvent and catalyst on the inherent viscosities of the polymers formed are studied. The glass transition temperatures of the polyphosphonates with biphenyl, phenylindane, and diphenylfluorene units are 120, 124, and 188°C, respectively. These polymers are self-extinguishing and are readily soluble in solvents such as N,N-dimethylacetamide, pyridine, tetrahydrofuran, and chloroform. They began to lose weight above 300°C in air. Copolyphosphonates from combinations of bisphenols and phenylphosphonic dichloride are also prepared and characterized.     

Synthesis and characterization of soluble polymides from 2,5-bis(4-aminophenyl)-3,4-diphenylthiophene and aromatic tetracarboxylic dianhydrides

2,5-Bis(4-aminophenyl)-3,4-diphenylthiophene, a polyimide-forming monomer, was prepared in three steps starting from benzyl chloride and sulfur. Novel polyimides were synthesized from the diamine and pyromellitic dianhydride or 3,3′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA). Polymerization was carried out either by the usual two-step procedure that included ring-opening polyaddition giving polyamic acids, followed by cyclodehydration to polyimides, or by the direct one-pot procedure involving cyclodehydration in situ. The polyimide derived from the diamine and BTDA, especially that prepared by the one-pot procedure in m-cresol containing isoquinoline, is soluble in various organic solvents and gave a yellow, transparent, tough, and flexible film. Solubility of this polyimide varied by the preparative method and by the copolymerization with bis(4-aminophenyl) ether. All the polyimides are highly thermally stable and exhibited no appreciable decomposition up to 450°C in air and nitrogen atmospheres.     

Electrical conductance of solutions of lithium nitrate in 1,3-diaminopropane

Electrical conductances and densities of the LiNO₃-1,3-diaminopropane system have been measured as a function of composition and temperature. The results suggest that the solvent molecules may act as bridges between Li⁺ ions at higher concentration of LiNO₃.