tereftalati

Tereftalati, or terephthalates, are esters derived from terephthalic acid, a benzene-1,4-dicarboxylic acid. They are typically diesters formed when both carboxyl groups are esterified with alcohols, yielding compounds such as dimethyl terephthalate (DMT) and diethyl terephthalate (DET). The term also covers a broader class of diesters used as monomers in polyester synthesis.

The structure consists of a para-disubstituted benzene ring bearing two ester groups. This rigid, linear arrangement contributes to the high thermal stability and stiffness characteristic of polyesters based on terephthalates, such as PET and PBT.

Production and uses: Terephthalic acid is produced primarily by oxidation of p-xylene. The esters, especially DMT and DET, are used as monomers in polyesters. PET (polyethylene terephthalate) is formed from either terephthalic acid or DMT with ethylene glycol, via esterification or transesterification followed by polycondensation. PET is widely used for beverage bottles, textile fibers, and films. Other terephthalate polymers, such as polybutylene terephthalate (PBT), are used in engineering plastics, resins, and coatings.

Recycling and environment: PET and other terephthalate polymers can be mechanically recycled or subjected to chemical recycling to recover monomers. The production and recycling of terephthalates have environmental implications in terms of energy use and emissions, but recycling programs and advances in catalysis and process design aim to improve sustainability.