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Dimethyl Terephthalate: Terephthalic Acid and Methanol Sprayed through a Hot Tube
Dimethyl terephthalate (DMT) is the methyl ester of terephthalic acid, a raw material for polyesters. Terephthalic acid does not melt, so Lotz and Gerlach (US 2,876,252, 1959) spray it as a suspension in methanol, with a little phosphoric acid, into a tube heated to 280–300 °C. The ester condenses as long needles that melt at 141 °C; the patent's yield was 97 %.
The picture: our diagram.
高级
Continuous
说明
1
1
Make the suspension
Make the suspension
Stir 1000 g of finely powdered terephthalic acid and 60 cc of 85 % phosphoric acid into 1000 cc of methanol.
此步骤所需材料：
对苯二甲酸1000 克
甲醇1000 毫升所需工具：
磷酸（85 %）
等臂天平
量筒
化学防溅护目镜
橡胶手套2
2
Heat the reaction tube
Heat the reaction tube
Heat a long cylindrical reaction tube electrically to 280–300 °C (the patent's was 300 cm long and 40 cm wide). A cooled condenser follows it.
所需工具：
加热反应管
带读数的热电偶
冷凝器盘管3
3
Spray it in with nitrogen
Spray it in with nitrogen
Spray the suspension with nitrogen through a nozzle into the tube, so the fine spray travels in a spiral along the tube wall. The acid and methanol react on the way.
所需工具：
雾化喷嘴
氮气瓶加热反应管
耐热手套4
4
Collect the needles
Collect the needles
The dimethyl terephthalate collects in the cooled condenser as long prismatic needles, melting point 141 °C. The patent's yield was 97 %.
所需工具：
冷凝器盘管橡胶手套5
5
Recycle nitrogen and methanol
Recycle nitrogen and methanol
Draw the nitrogen and the excess methanol out with a membrane (diaphragm) pump and send them round again.
所需工具：
隔膜泵氮气瓶此蓝图制作
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