HYDROXYETHYL TEREPHTHALATE

The ethylene glycol liberated by reaction (5.L) is removed by lowering the pressure or purging with an inert gas. Because the ethylene glycol produced by reaction (5.L) is removed, proper stoichiometry is assured by proceeding via the intermediate, bis(2-hydroxyethyl) terephthalate otherwise the excess glycol used initially would have a deleterious effect on the degree of polymerization. Poly(ethylene terephthalate) is more familiar by some of its trade names Mylar as a film and Dacron, Kodel, or Terylene as fibers it is also known by the acronym PET. 

Terephthahc acid (TA) or dimethyl terephthalate [120-61 -6] (DMT) reacts with ethyleae glycol (2G) to form bis(2-hydroxyethyl) terephthalate [959-26-2] (BHET) which is coadeasatioa polymerized to PET with the elimination of 2G. Moltea polymer is extmded through a die (spinneret) forming filaments that are solidified by air cooling. Combinations of stress, strain, and thermal treatments are appHed to the filaments to orient and crystallize the molecular chains. These steps develop the fiber properties required for specific uses. The two general physical forms of PET fibers are continuous filament and cut staple. 

Bis-(P-hydroxyethyl) terephthalate and related compounds can be produced ia this manner using finely divided carbon catalyst (92). The carbon functions not only as a catalyst but also helps to remove color from the reaction mixture upon removal of the carbon by hot filtration. 

In addition to this diester, di-2-hydroxyethyl terephthalate, some oligomers of general structure ... 

An alternative route to PET is by the direct reaction of terephthalic acid and ethylene oxide. The product bis(2-hydroxyethyl)terephthalate reacts in a second step with TPA to form a dimer and ethylene glycol, which is released under reduced pressure at approximately 300°C. 

Linear step-growth polymerizations require exceptionally pure monomers in order to ensure 1 1 stoichiometry for mutually reactive functional groups. For example, the synthesis of high-molecular-weight polyamides requires a 1 1 molar ratio of a dicarboxylic acid and a diamine. In many commercial processes, the polymerization process is designed to ensure perfect functional group stoichiometry. For example, commercial polyesterification processes often utilize dimethyl terephthalate (DMT) in the presence of excess ethylene glycol (EG) to form the stoichiometric precursor bis(hydroxyethyl)terephthalate (BHET) in situ. 

PET is the polyester of terephthalic acid and ethylene glycol. Polyesters are prepared by either direct esterification or transesterification reactions. In the direct esterification process, terephthalic acid is reacted with ethylene glycol to produce PET and water as a by-product. Transesterification involves the reaction of dimethyl terephthalate (DMT) with ethylene glycol in the presence of a catalyst (usually a metal carboxylate) to form bis(hydroxyethyl)terephthalate (BHET) and methyl alcohol as a by-product. In the second step of transesterification, BHET... 

To a stainless steel reactor equipped with a heating mantle, a charging port, a condenser for removing ethylene glycol, an inert gas inlet, and a sampling valve were added 400 g of bis(2-hydroxyethyl)terephthalate, 136 g of ethylene glycol, and 0.035 g (or 0.225 g) of sodium acetate trihydrate. The temperature was raised to between 190 and 200°C in 1 h and then 454 g of waste polyester... 

BFPPO monomer, sulfonated, 357-358 BF1ET. See Bis(hydroxyethyl)terephthalate (BHET)... 

Bis(2-hydroxyethyl) terephthalate, Ethanol, Ethylene glycol 491M, 1975, 303... 

Bis(azide)—rubber resists, 15 157 Bis-(P-hydroxyethyl) terephthalate, 10 487 Bis(biphenyl) chromium(I) iodide, physical properties, 6 528t Bis(carbamoyl) peroxides, 18 477 Biscarbonato uraniumfVI) complexes, 25 431... 

Tomita, K., Studies on the formation of polyethylene terephthalate 6. Catalytic activity of metal compounds in polycondensation of bis(hydroxyethyl)terephthalate, Polymer, 17, 221-224 (1976). 

Wang X, Lu D, Jonsson LJ et al (2008) Preparation of a PET-hydrolyzing lipase from Aspergillus oryzae by the addition of bis(2-hydroxyethyl) terephthalate to the culture medium and enzymatic modification of PET fabrics. Eng Life Sci 8 268-276... 

Polymer was prepared as follows. Bis (/3-hydroxyethyl) terephthalate (4/14 mole) reacted with terephthalic acid (TA) (3/14 mole) at 275°C using Sb203 as polycondensation catalyst. To the resulting polymer ([17] 0.41, COOH content 51.3 eq/10 g, and diethylene glycol content 0.60 mole %/TA) was added POC, followed by 15 minutes at high vacuum. 

Bis(2-hydroperoxy-2-propyl)benzene, 3535 1,4-Bis(2-hydroperoxy-2-propyl)benzene, 3536 B is(2-hydroxyethyl)methylphosphine, 2029 Bis(2-hydroxyethyl) terephthalate, 3520 Bis(hydroxylamine)zinc chloride, 4061 Bis(hydroxymethyl) peroxide, 0924... 

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