Cyclohexane-1,4-dimethylol

Figure 17-1. Intrinsic viscosity [tj] as a measure of molar mass and its dependence on the initial molar ratio of mol glycol/ mol TME in the polycondensation of dimethyl terephthalate TME with cyclohexane-1,4-dimethylol (C) or ethylene glycol (E) (after H.-G. Elias). Theory for the polycondensation of equivalent quantities of TME and in the absence of physical and chemical side reactions (p = I).

A polyester related to PET is obtained from cyclohexane-1,4-dimethylol and dimethyl terephthalate ... 

Unlike poly(ethylene terephthalate), the polyester from dimethyl terephthalate and cyclohexane-1,4-dimethylol can be manufactured with initially equivalent monomer quantities. It has improved dyeability, just as in the case of the copolymer of dimethyl terephthalate, ethylene glycol, and 5-10% p-hydroxybenzoic or isophthalic acid. 

The first reaction takes place at between 160 and 180 0, under 30 to 40.106 Pa absolute, in the presence of supported palladium. The operation is conducted in solution in the ester formed to prevent excessive temperature rise due to the exothermicity of the reaction. Molar selectivity of the saturated ester exceeds 95 per cent The crude product obtained is sent to a hydrogenolysis reactor, where it is converted to dimethylol cyclohexane and methanol in the presence of copper chromite. The dimethylol cyclohexane obtained contains about 33 per cent of the cis isomer and 76 per cent of the trans isomer. 

A polyester from terephthalic acid and 1,2-dimethylol cyclohexane is produced mainly for use in fibers. This polymer is also formed from dimethyl terephthalate and the diol by a transesterification reaction. The material has the following structure ... 

Mixed dicarboxylic acids are usually used to form copolyesters. For instance, terephthalic and isophthalic acids are reacted together with 1,4-dimethylol cyclohexane to form a copolyester. The product is amorphous and transparent. Another copolyester is manufactured from terephthalic, isophthalic, and an aliphatic dicaiboxylic acid like adipic with either 1,4-butanediol or 1,6-hexanediol. The aliphatic dicarboxylic acid is used in minor quantities. Many such copolyesters are used as high strength adhesives. 

Kodel>2 Polyester from terephthalic acid and 1,4-dimethylol cyclohexane Eastman, U.S. 

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