Poly isomeric, pathways

Interest is shown still in the isomerization of stilbene and its derivatives. A study of the pathways for the cis -trans isomerization of 4-nitro, 4,4-dinitro, and 4-nitro-4 -methoxy stilbenes has been reported. The dynamics of the photoisomerization of stilbenes in hydrocarbon solution has been studied and a comparison of the trans -cis isomerization of stilbene in low viscosity liquid alkanes and in the gas phase has been carried out. The photoisomerization of stilbene in straight chain alcohols has provided evidence for the existence of rotational relaxation in the excited and the ground states. An analysis of the isomerization rates of photoexcited stilbene has been made and the photobehaviour of poly deuteriated stilbene has been studied. ... 

Attempts had been made to synthesise polyesters based on phthalic acid as the diacid component, but these products were amorphous, had low softening points, and were rapidly attacked by organic solvents and acids and bases. Research into polyesters made by the reaction of terephthalic acid (or esters thereof) with aliphatic diols, led to the discovery of polyesters of high commercial value poly(alkylene terephthalate)s [4]. This pairing of diols with terephthalic acid eventually led to the most commercially successful aromatic polyesters, but other synthetic pathways were also investigated towards such products in the early days of polyester development. These included the self-condensation of hydroxy acids of the structure -H0-R-Ph-C02H, where R-OH is para to the acid group and R is -(CH2)- or -(CH2)2- [5], and reactions of aliphatic diacids with 1,4-dihydroxy benzene and similar aromatic diols [6, 7]. Also synthesised about the same time were polyesters based on C2-Cg aliphatic diols and any of the isomeric naphthalene dicarboxylic acids [8]. 

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