Diethyl phthalate [ C4H6O5 ]

Diethyl phthalate (DEP) is a clear substance that is liquid at room temperature and is slightly denser than water with low volatility.

This synthetic substance is commonly used to make plastics more flexible. Products include toothbrushes, perfumes, automobile parts, tools, cosmetics, insecticides, aspirin, food packaging, toys, plastic packaging films, toiletries, and medical treatment tubing. It can be used as additive in polysulfide rubber to reduce shear strength and facilitates easy mixing for adhesives.

Since the compound is a suitable solvent for many organic molecules, it is often used to bind cosmetics and fragrances. DEP was reported as an ingredient in 67 cosmetic formulations, including bath preparations (oils, tablets, and salts), eye shadow, toilet waters, perfumes and other fragrance preparations, hair sprays, wave sets, nail polish and enamel removers, nail extenders, bath soaps, detergents, aftershave lotions, incense sticks, and skin care preparations.

DEP is used as a plasticizer for cellulose ester plastic films and sheets (photographic, blister packaging, and tape applications). In addition, DEP is used as a component in insecticide sprays and mosquito repellents, as a camphor substitute, as a plasticizer in solid rocket propellants, as a wetting agent, as a dye application agent for triacetate dyes, as an ingredient in aspirin coatings, as a diluent in polysulfide dental impression materials, and in adhesives, plasticizers, and surface lubricants used in food and pharmaceutical packaging.