Dimethyl terephthalate

Dimethyl terephthalate (DMT) can be prepared via a direct esterification of terephthalic acid with methanol: : On a commercial scale, this reaction is usually done at using o-xylene as a solvent. The dimethyl terephthalate that is formed is then purified by distillation. Even terephthalic acid of low purity may be used in this method. Alternatively, it can be prepared from para-xylene by alternating oxidation and methyl-esterification steps via methyl para-toluate (PT). ==Uses==

DMT is used in the production of polyesters, including polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), and polybutylene terephthalate (PBT). These polymers are produced by transesterification with a diol. In the production of PET, the transesterification initially produces 2-hydroxyethyl methyl terephthalate. Hydrogenation of DMT affords the diol cyclohexanedimethanol, which is a useful monomer. ==Hazards==

DMT is not directly dangerous to humans, but it is harmful to aquatic organisms, so environmental releases are avoided. It is flammable and the dust may form explosive mixtures with air. ==References==