| 摘要 |
The invention relates to a method for producing tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=3,4) by reacting formaldehyde with methanol followed by a distillative processing of the reaction mixture with the following steps: a) feeding an aqueous formaldehyde solution and methanol in to a reactor and reacting; b) feeding reaction mixture a into a reactive evaporator and separating it into a low-boiling fraction b1 containing formaldehyde, water, methanol, methylene glycol, polyoxymethylene glycols, hemiformals, methylal and polyoxymethylene glycol dimethyl ether (POMDMEn&gt ;i) and a high-boiling fraction b2 and returning the high-boiling fraction b2 in to the reactor (step a)); c) feeding the low-boiling fraction b1 into a first distillation column and separating it into a low-boiling fraction c1 containing formaldehyde, water, methylene glycol, methanol, hemiformals, methylal, di-, tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=2,3,4) and into a high-boiling fraction c2 and returning the high- boiling fraction c2 into the reactive evaporator (step b)); d) feeding the l ow- boiling fraction c1 into a second distillation column and separating it into a low-boiling fraction d1 and into a high-boiling fraction d2 consisting of formaldehyde, water, methylene glycol, polyoxymethylene glycols, tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=3,4); e) feeding the high- boiling fraction d2 into a phase separating apparatus and separating it into an aqueous phase e1 consisting of formaldehyde, water, methylene glycol and polyoxymethylene glycols and into an organic phase e2 containing tri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=3,4); f) feeding the organi c phase e2 into a third distillation column and separating it into a low-boili ng fraction f1 consisting of formaldehyde, water, methylene glycol and polyoxymethylene glycols and into a high-boiling fraction f2 consisting of t ri- and tetraoxymethylene glycol dimethyl ether (POMDMEn=3,4).
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