| 摘要 |
A process for preparing tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=3,4) by reacting formaldehyde with methanol and subsequently workin g up the reaction mixture by distillation, comprising the steps of: a) feeding aqueous formaldehyde solution and methanol into a reactor and reacting to gi ve a mixture a comprising formaldehyde, water, methylene glycol (MG), polyoxymethylene glycols (MGn>1), methanol, hemiformals (HF), methylal (POMDMEn=1) and polyoxymethylene glycol dimethyl ethers (POMDMEn>1); b) feeding the reaction mixture a into a first distillation column and separati ng into a low boiler fraction b1 and a high boiler fraction b2 comprising formaldehyde, water, methanol, polyoxymethylene glycols, hemiformals and polyoxymethylene glycol dimethyl ethers (POMDMEn>1); c) feeding the high boiler fraction b2 into a second distillation column and separating into a l ow boiler fraction c1 comprising formaldehyde, water, methylene glycol, polyoxymethylene glycols, methanol, hemiformals, di-, tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=2,3,4) and a high boiler fraction c2; d) feeding the low boiler fraction c1 into a third distillation column and separating into a low boiler fraction d1 and a high boiler fracti on d2 substantially consisting of formaldehyde, water, methylene glycol, polyoxymethylene glycols, tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=3,4); e) feeding the high boiler fraction d2 into a phase separatio n apparatus and separating into an aqueous phase e1 substantially consisting o f formaldehyde, water, methylene glycol and polyoxymethylene glycols, and an organic phase e2 comprising tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=3,4); f) feeding the organic phase e2 into a fourth distillation column and separating into a low boiler fraction f1 substantially consisting of formaldehyde, water, methylene glycol and polyoxymethylene glycols, and a high boiler fraction f2 substantially consisting of tri- and tetraoxymethyle ne glycol dimethyl ether (POMDMEn=3,4).
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