Production

Polyethylene terephthalate is produced from ethylene glycol and dimethyl terephthalate (C6H4(CO2CH3)2) or terephthalic acid.8

The above is a transesterification reaction, admitting the closing is an esterification reaction.

editDimethyl terephthalate process

In dimethyl terephthalate process, this admixture and balance ethylene glycol are reacted in the cook at 150–200 °C with a basal catalyst. Methanol (CH3OH) is removed by beverage to drive the acknowledgment forward. Balance ethylene glycol is distilled off at college temperature with the aid of vacuum. The additional transesterification footfall gain at 270–280 °C, with connected beverage of ethylene glycol as well.8

The reactions are arcadian as follows:

First step

C6H4(CO2CH3)2 + 2 HOCH2CH2OH → C6H4(CO2CH2CH2OH)2 + 2 CH3OH

Second step

n C6H4(CO2CH2CH2OH)2 → (CO)C6H4(CO2CH2CH2O)n + n HOCH2CH2OH

editTerephthalic acerbic process

In the terephthalic acerbic process, esterification of ethylene glycol and terephthalic acerbic is conducted anon at abstinent burden (2.7–5.5 bar) and top temperature (220–260 °C). Water is alone in the reaction, and it is aswell continuously removed by distillation:8

n C6H4(CO2H)2 + n HOCH2CH2OH → (CO)C6H4(CO2CH2CH2O)n + 2n H2O