Synthesis of poly(methylene terephthalate) and copolymers with poly(ethylene terephthalate)

Poly(methylene terephthalate) (PMT) and poly(ethylene terephthalate) (PET) were synthesized by triethylamine-mediated reactions of terephthalic acid a nd dihalomethanes or 1,2-dihaloethanes, respectively. Reactions with chloro compounds required longer reaction times and higher temper-atures than tho se with bromo. Copolymers were synthesized by using proportionate amounts o f dihalomethane/1,2-dihaloethane mixtures. Copolymer compositions were dete rmined by inte-grations of relative areas of methylene and ethylene H-1 NMR peaks. Mn values were determined from H-1 NMR end group signals. Mole frac tion feed is linearly related to CH2/CH2CH2 incorporation into copolymer pr oducts. Mechanisms are proposed to explain results.