Hydroquinone

Hydroquinone (CAS 123-31-9), commonly abbreviated as HQ, is an aromatic diol used industrially as a polymerization inhibitor, antioxidant, and chemical intermediate. It prevents premature crosslinking in reactive monomers and protects unstable materials during storage. In photographic and printing chemistry, HQ functions as a developing agent that reduces silver halide to metallic silver, controlling image density and contrast. Rubber and polymer manufacturers add it to acrylic and vinyl monomers during production.

This addition occurs during transport to suppress unwanted polymerization. As a pharmaceutical intermediate, it supports synthesis of active compounds and is used in topical formulations targeting skin hyperpigmentation for various medical applications. Personal care formulators incorporate HQ into depigmentation products where it inhibits melanin synthesis, subject to regional regulatory limits. The compound is essential for maintaining the stability of sensitive chemical formulations.

Hydroquinone is supplied as a white crystalline powder in technical and pharmaceutical grades. USP and BP grades are available to meet compendial requirements for pharmaceutical and cosmetic applications globally. Technical grade is standard for polymer stabilization and industrial chemical synthesis, typically packaged in fiber drums or multi-wall bags. This ensures the material remains stable and free from contaminants during long-term storage.