Trimellitic anhydride (TMA), the anhydride of1,2.4-benzenetricarboxylic acid is the cyclic anhydride of trimellitic acid. It is a colorless to white solid.

Trimellitic anhydride is principally used in the production of powder coatings, heat-resistant polyvinyl chloride trimellitic plasticisers, polyimide insulation paints, as curing agents of epoxy resins, and in the modification of alkyd resin paints. Several thousand tons of this compound are produced annually as a precursor to plasticizers for polyvinyl chloride. 

Trimellitic anhydride has been found to induce asthma,rhinitis and a late-onset res-piratory syndrome with systemic symptoms, as well asan irritative bronchitis. The data now reported sug-gest the possible involvement of an immunologicalmechanism in some responses to occupational ex-posure to this cormpound.

Reference

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