12Benzenedicarboxylic

12benzenedicarboxylic is most commonly known as 1,2-benzenedicarboxylic acid, or phthalic acid. It is an aromatic dicarboxylic acid with the formula C8H6O4. The molecule features a benzene ring bearing two adjacent carboxyl groups (an ortho-relationship), giving it properties typical of diacids used as chemical intermediates.

Phthalic acid is a white to almost white crystalline solid that is sparingly soluble in water but dissolves in hot water and many organic solvents. It decomposes on prolonged heating and, at higher temperatures, readily dehydrates to phthalic anhydride. The acid forms esters known as phthalate esters when reacted with alcohols; these esters are widely used as plasticizers.

Industrial production and occurrence: the principal industrial route to phthalic acid derivatives involves oxidation of suitable alkylbenzenes, most notably o-xylene, to form phthalic anhydride, which can be hydrolyzed or reacted to yield phthalic acid or its derivatives. It can also be derived from oxidation of naphthalene. In academia and industry, the term phthalic acid is often used interchangeably with its anhydride form, depending on the context.

Uses: phthalic acid and its derivatives are key intermediates in the manufacture of plasticizers for polyvinyl chloride (PVC), alkyd resins, unsaturated polyesters, dyes, and various specialty chemicals. Phthalate esters, in particular, have widespread use as plasticizers, though environmental and health concerns have led to increased regulation and the development of alternatives.

Safety: phthalic acid is corrosive to skin and eyes and can cause respiratory irritation. It should be handled with appropriate PPE, good ventilation, and proper waste disposal according to regulatory guidelines. Environmental persistence is a concern for some phthalate esters derived from it.