|
|Section2= |Section7= }} Dimethyl terephthalate (DMT) is an organic compound with the formula C6H4(CO2CH3)2. It is the diester formed from terephthalic acid and methanol. It is a white solid that melts to give a distillable colourless liquid.〔Richard J. Sheehan "Terephthalic Acid, Dimethyl Terephthalate, and Isophthalic Acid" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.〕 ==Production== Dimethyl terephthalate (DMT) has been produced in a number of ways. Conventionally and still of commercial value is the direct esterification of terephthalic acid. Alternatively, it can be prepared by alternating oxidation and methyl-esterification steps from p-xylene via methylp-toluate.〔 Dimethyl Terephthalate (DMT) (Witten Process) The common method for the production of DMT from para-xylene (PX) and methanol consists of four major steps: oxidation, esterification, distillation, and crystallization. A mixture of p-xylene (PX) and p-Toluic ester (PT) is oxidized with air in the presence of a heavy metal catalyst (Co/Mn). The acid mixture resulting from the oxidation is esterified with methanol (MeOH, CH3OH) to produce a mixture of esters. The crude ester mixture is distilled to remove all the heavy boilers and residue produced; the lighter esters are recycled to the oxidation section. The raw DMT is then sent to the crystallization section to remove DMT isomers, residual acids and aromatic aldehydes.〔http://www.gtctech.com/technology-licensing/polyester-technologies/dimethyl-terephthalate-technology/〕 1) p-xylene oxidation to p-Toluic acid at 140–180 ⁰C & 500–800 kPa. :P-xylene oxidation to p-toluic acid 2) Esterification of the resulting acid with methanol results in Methyl p-toluate at 250⁰C and 2500 kPa and subsequent oxidation and esterification of Methyl p-toluate yields Dimethyl terephthalate (DMT) as shown in the below reaction:〔 :Esterification of the resulting acid with methanol Dimethyl Terephthalate (DMT) production through Direct Esterification If highly impure Terephthalic acid is available, DMT can be made in a separate process by esterification with methanol to dimethyl terephthalate which is then purified by distillation: :C8H6O4 (TPA) + 2CH3OH (Methanol) → C10H10O4 (DMT) + 2 H2O at presence of o-xylene at 250–300 ⁰C. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「dimethyl terephthalate」の詳細全文を読む スポンサード リンク
|
