Chemical properties:
Hydroquinone is also known as hydroquinone and 1.4-benzene. Molecular formula C6H6O2. Molecular weight 110.11. Colorless or white crystals. It changes color easily when exposed to light in the air. Its aqueous solution can oxidize to brown in the air, and oxidizes faster in alkaline medium. Melting point 1Chemicalbook70～171℃, boiling point 285～287℃, relative density 1.33215, UVλmax288nm in water. It is easily soluble in hot water, ethanol and ether, and slightly soluble in benzene. It is chemically active and easily oxidized, and can also undergo esterification, substitution and other reactions. Hydroquinone is an important organic developer and can only work in a strong alkaline solution. The reduction speed is slower than that of metol, but once the image appears, the density increases rapidly, and a larger contrast can be obtained. The fastest development temperature is 27°～29℃, slows down below 15℃, and almost stops below 5℃. Large amounts can make the photo look warm. Used as common photographic developer; physical developer and redeveloper reducing agent. Generally used in combination with phenidone and metol.
Uses:
1. Hydroquinone is an intermediate of the herbicides quizalofop-p-ethyl, fluazifop-p-ethyl, thiazolyl-p-ethyl, oxadiazol-p-ethyl, fluazifop-p-ethyl, and lactofen-p-ethyl, and is also an intermediate of medicine and dyes.
2. Hydroquinone is mainly used as a developer for photography. Hydroquinone and its alkylated products are widely used as inhibitors added during the storage and transportation of monomers, with a commonly used concentration of about 200 ppm. Hydroquinone monomethyl ether is an intermediate of edible oil antioxidant BHA; hydroquinone dimethyl ether is an intermediate of dyes, organic pigments and fragrances; hydroquinone diethyl ether is an intermediate of photosensitive pigments and dyes. Hydroquinone is also used to prepare N, N’-diphenyl-p-phenylenediamine, which is an antioxidant and deodorant for rubber and gasoline.
3. Colorimetric determination of phosphorus, magnesium, niobium, copper, silicon and arsenic; polarographic and volumetric determination of iridium; reducing agent of heteropolyacids; reducing agent of copper and gold; testing of phosphate, tungstate, nitrate, nitrite, selenium and tellurium; developer; antioxidant; desulfurizer in fertilizer industry; urea synergist.