<unk>  esters are the dialkyl or alkyl aryl esters of phthalic acid (also called 1,2-benzenedicarboxylic acid, not be confused with the structurally isomeric terephthalic or isophthalic acids); the name<unk> " derives from phthalic acid, which itself is derived from the word "naphthalene". When added to plastics,<unk> s allow the long polyvinyl molecules to slide against one another. The<unk> s have a clear syrupy liquid consistency and show low water solubility, high oil solubility, and low volatility. The polar carboxyl group contributes little to the physical properties of the<unk> s, except when R and R' are very small (such as ethyl or methyl groups).<unk> s are colorless, odorless liquids produced by reacting phthalic anhydride with an appropriate alcohol (usually 6- to 13-carbon). The mechanism by which<unk> s and related compounds effect plasticization to polar polymers has been a subject of intense study since the 1960s. The mechanism is one of polar interactions between the polar centres of the<unk>  molecule (the C=O functionality) and the positively charged areas of the vinyl chain, typically residing on the carbon atom of the carbon-chlorine bond. For this to be established, the polymer must be heated in the presence of the plasticizer, first above the Tg of the polymer and then into a melt state. This enables an intimate mix of polymer and plasticizer to be formed, and for these interactions to occur. When cooled, these interactions remain and the network of PVC chains cannot reform (as is present in unplasticized PVC, or PVC-U). The alkyl chains of the<unk>  then screen the PVC chains from each other as well. They are blended within the plastic article as a result of the manufacturing process. Because they are not chemically bonded to the host plastics,<unk> s are released from the plastic article by relatively gentle means. For example, they can be removed by heating or by extraction with organic solvents. Alternatives Market trend in decreasing use of low orthophthalates including DEHP Being inexpensive, nontoxic (in an acute sense), colorless, noncorrosive, biodegradable, and with easily tuned physical properties,<unk>  esters are nearly ideal plasticizers. Among the numerous alternative plasticizers are Dioctyl terephthalate (DEHT) (a terephthalate isomeric with DEHP) and 1,2-Cyclohexane dicarboxylic acid diisononyl ester (a hydrogenated version of DINP). Many bio-based plasticizers based on vegetable oil have been developed. It is a ready substitute for dioctyl<unk> .
Phthalate
Photoanethole
Tetraethyllead
Dichloroacetic acid
Diiodohydroxyquinoline
Dicoumarol
Selenous acid
Tetrachlorodecaoxide