Dimethyl terephthalate (DMT) is an organic compound with the formula . It is the diester formed from terephthalic acid and methanol. It is a white solid that melts to give a distillable colourless liquid. it is an intermediate in some schemes for the recycling of PET, e.g. from plastic bottles.
Production
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).
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.