DIOCTYL PHTHALATE
Chemical Formula : C6H4(COOC8H17)2 CAS Registry Number : 117-81-7
Dioctyl Phthalate/Bis(2-ethylhexyl)phthalate (BEHP), is an organic compound with the formula C6H4(CO2C8H17)2. It is the most important "phthalate," being the diester of phthalic acid and the branched-chain 2-ethylhexanol. This colourless viscous liquid is soluble in oil, but not in water. It possesses good plasticizing properties. Being produced on a massive scale by many companies, it has acquired many names and acronyms, including BEHP and di-2-ethyl hexyl phthalate.
Production
The process entails the reaction of phthalic anhydride with 2-ethylhexanol:C6H4(CO)2O + 2 C8H17OH → C6H4(CO2 C8H17)2 + H2O
Applications
Phthalates are by far the most widely used plasticisers, primarily to make soft and flexible polyvinyl chloride (PVC) for the applications in the industry of automotive, building & construction material, cable, flooring, medical device and toys. Phthalates make the long polyvinyl molecules to slide against one another. Minor quantity of phthalates are used in adhesives, caulk, sealants, paint to improve work performance. Small molecule phthalates are used as solvents in perfumes to provide longer linger longer and in nail polish to prevent chipping. They are also used as ingredients of insect repellents, as solvents in lacquer and pesticides, and as dye carrier. They are used as textile lubricating agents and as solid rocket propellents. Phthalates are produced by the reaction of phthalic anhydride with appropriate alcohols from methanol up to isodecanol (C13), either as a straight chain or with some branched in the presence of concentrated sulphuric acid as a catalyst. Excess alcohols are recovered and recycled and phthalates are purified by vacuum distillation and/or activated charcoal. A wide range of phthalates of varying chain length and structure provides each adequate properties and cost-effective for various processing and mechanical requirements. C8 - C9 phthalates, such as di-2-ethyl hexyl phthalate (DEHP or called DOP), diisodecyl phthalate (DIDP) and diisononyl phthalate (DINP) are the most widely used general purpose phthalates. DOP is the dominant plasticizer used in PVC, providing low cost. Short chain phthalates (C3 - C7) are used when rapid setting and stain resistance is required. 2-Ethyl hexanol, produced by the dimerisation of butyraldehyde obtained from propylene, is cheaper than isononyl alcohol which are prepared by the carbonylation of an olefin. Long chain phthalates (C11 - C13) are used when high temperature stability is required. C1 and C2 phthalates are used as solvents. Special phthalates which contain aromatic ring in the side chain are used when fast-fused is required. Diallyl phthalate is used as a crosslinking agent, plasticizer or dying carrier for polyesters.
