Bis(2-ethylhexyl) phthalate

Bis(2-ethylhexyl) phthalate (di-2-ethylhexyl phthalate, diethylhexyl phthalate, diisooctyl phthalate, DEHP; incorrectly — dioctyl phthalate, DIOP) is an organic compound with the formula C6H4(CO2C8H17)2. DEHP is the most common member of the class of phthalates, which are used as plasticizers. It is the diester of phthalic acid and the branched-chain 2-ethylhexanol. This colorless viscous liquid is soluble in oil, but not in water. Di(2-ethylhexyl) phthalate is produced commercially by the reaction of excess 2-ethylhexanol with phthalic anhydride in the presence of an acid catalyst such as sulfuric acid or para-toluenesulfonic acid. It was first produced in commercial quantities in Japan around 1933 and in the United States in 1939. DEHP has two stereocenters, located at the carbon atoms carrying the ethyl groups. As a result, it has three distinct stereoisomers, consisting of an (R,R) form, an (S,S) form (diastereomers), and a meso (R, S) form. As most 2-ethylhexanol is produced as a racemic mixture, commercially-produced DEHP is therefore almost always racemic as well, and consists of equal amounts of all three stereoisomers. Due to its suitable properties and the low cost, DEHP is widely used as a plasticizer in manufacturing of articles made of PVC. Plastics may contain 1% to 40% of DEHP. It is also used as a hydraulic fluid and as a dielectric fluid in capacitors. DEHP also finds use as a solvent in glowsticks. Approximately three million tonnes are produced and used annually worldwide. Manufacturers of flexible PVC articles can choose among several alternative plasticizers offering similar technical properties as DEHP. These alternatives include other phthalates such as diisononyl phthalate (DINP), di-2-propyl heptyl phthalate (DPHP), diisodecyl phthalate (DIDP), and non-phthalates such as 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH), dioctyl terephthalate (DOTP), and citrate esters. DEHP is a component of many household items, including tablecloths, floor tiles, shower curtains, garden hoses, rainwear, dolls, toys, shoes, medical tubing, furniture upholstery, and swimming pool liners.