Terephthalic acid dimethylester

Gruschke, H Hammerschick, W. and Medem, H Process for depoly-merizing poly(ethylen terephthalate) to terephthalic acid dimethylester, US Patent 3 403 115 (1968). 

Phthalocyanines with M = Si(OH)2 or Ge(OH)2 were eovalently incorporated into polyesters during the polycondensation of terephthalic acid dimethylester and ethylene glycol [182]. With only lO" molar amounts of dye, the polyesters are intensely blue-colored. Good solubility can be achieved in water by axial substitution at the central metal or with hydrophilic polymers. Phthalocyanines with the tetravalent M = SiCb were reacted with the sodium salt of methoxypoly(oxyethylene) (M = 5000 Da) to give the blue-colored polymer 68 which is soluble in water and some organic solvents [183]. The reaction of phthalocyanines with the trivalent M = AlCl with poly-(oxyethylene) or poly(vinylalcohol) also led to water-soluble polymers having covalent bonds of the polymers at the Al(III) [184]. These water-soluble materials have been tested in the photodynamic therapy of cancer. 

The diacid mainly used in the production process for poly(ester-imide) based wire enamel is terephthalic acid (or its dimethylester) (6). Resins are known where isophthalic [46] and phthalic acid [47] are used. The large tonnage products all contain the terephthalic unit. The cured films have better thermal and mechanical properties (e.g., a higher hardness), important when the coated wires are processed in high speed winding machines. 

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