MHET

MHET, or mono(2-hydroxyethyl) terephthalate, is a monoester derived from terephthalic acid and ethylene glycol. It is one of the soluble products formed when polyethylene terephthalate (PET) is depolymerized, either chemically by hydrolysis or enzymatically. In enzymatic PET degradation, PETases release MHET and bis(2-hydroxyethyl) terephthalate (BHET) from the polymer, and MHETase can further hydrolyze MHET to terephthalic acid and ethylene glycol, thereby contributing to a recycling pathway.

In practical terms, MHET is considered a key intermediate in PET recycling processes. It can be isolated from depolymerization mixtures and processed further to obtain monomeric building blocks or other value-added products. Its role as an intermediate helps researchers understand the efficiency and specificity of depolymerization pathways, including enzyme performance and process optimization.

Chemically, MHET is the monoester of terephthalic acid with ethylene glycol, reflecting its origin from PET’s repeating ester linkage. The compound serves as a useful marker in studies of microbial and enzymatic PET degradation and is a focal point for efforts to improve recycling efficiency and closed-loop material recovery in PET-based systems.