methanolysis

Methanolysis is a chemical reaction in which methanol participates to cleave chemical bonds or to replace a leaving group with a methoxy group. In organic chemistry it is most commonly described as alcoholysis using methanol as the nucleophile, often proceeding via nucleophilic acyl substitution when esters are involved.

In ester chemistry, methanolysis converts esters into their corresponding methyl esters and an alcohol: RCOOR' + CH3OH → RCOOCH3 + R'OH. The reaction is typically accelerated by acid, base, or enzyme catalysts and can be reversible, depending on conditions and the leaving group.

In polymer chemistry, methanolysis is used to depolymerize polyesters such as polyethylene terephthalate (PET) to dimethyl terephthalate and ethylene glycol, enabling chemical recycling of the polymer. It also underlies transesterification processes in biodiesel production, where triglycerides react with methanol to form fatty acid methyl esters and glycerol; catalysts can be basic, acidic, or enzymatic, and reaction conditions are chosen to drive formation of methyl esters.

Applications and notes: methanolysis is used in chemical recycling, biodiesel manufacturing, and synthesis of methyl esters; it requires handling of methanol and appropriate catalysts; safety concerns include methanol's toxicity and flammability. The term can also refer more broadly to methanol acting as solvent in methanol-assisted hydrolysis in various systems.