PROCESS FOR PRODUCING DIPENTAERYTHRITOL

摘要

Prepn. of dipentaerythritol (D-PE) comprises; (1) condensation reaction of pentaerythritol (PE) in liq. state in the presence of acidic catalyst at 200-260 deg.C; (2) crystallisation of one part of PE by lowering the temp. of the reaction mixt.; and (3) removal of PE. Reaction mixt. obtd. after step (3) has high concn. of D-PE Opt. the prepn. is conducted in a polar solvent. Before the conversion rate of PE exceeds 25%, the temp. of the reaction mixt. is lowered to less than 195 deg.C. Alternatively, before the wt. ratio of D-PE/PE exceeds 0.18, the temp. is lowered to less than 195 deg.C (pref. 40-160 deg.C). Prepn. further comprises sepg. D-PE from the reaction soln. Polar solvent has a dielectric constant of 15-100. Polar solvent is from dimethylformamide, dimethyl sulphoxide, tributylphosphate, esp. sulpholane, 1,3-dimethyl-2-imidazoli-di-none (sic), and/or water.