Aliphatic cyclic carbonate(s) containing a six membered ring

摘要

Optionally stabilised cyclic carbonates of formula (I) are prepared by esterification of 1,3 propanediol compounds of formula (II) with carbonic acid esters of formula (III) to form oligo- or polycarbonates and by subsequent distillative depolymerisation of the resulting oligo- or polycarbonate to form (I). The reaction mixture contains 0.001-5, preferably 0.03-0.1 wt.% (w.r.t. (II) and (III)) of a catalyst consisting of tin, titanium and/or zirconium compounds. Ester exchange is carried out at 120-180 preferably 150-170 deg C and the depolymerisation step is performed at 150-280 (190-250), preferably 200-240 deg C. Depolymerisation is carried out at a temperature 30-150 deg C higher than that of the ester exchange reaction. Optionally the resulting distillation residue is recycled (50-100%) to the ester exchange reaction step. (I) can be stabilised against polymerisation by the addition of 0.001-5 wt.% of a compound (IV) consisting of sulphur and/or phosphorous acids or the correspond ing esters and salts. A mixture of (I) and 0.001-5 wt.% (IV), optionally with 2-500, (3-300), preferably 5-200 wt.% (w.r.t. (I) and (IV)) of an ether, ketone and/or nitrile solvent preferably an ester, amide, lactam and/or lactone solvent is also claimed. R, R<1> = H, 1-6C alkyl, 3-7C cycloalkyl, -CH2OR<2>, or 6-12C aryl (R<1> only) R<2> = H, 1-4C alkyl, allyl, methallyl or benzyl, whereby two R<2> groups together = -CH2-, -CH(CH3)-, -CH(C2H5)-, -CH(C6H5)- or -CH(C3H7)- R and R<1> together with the substituted C atom = cyclopentane-, cyclohexane cycloheptane, oxetane, tetrahydrofuran-, tetrahydropyran or dioxane R<3> = 1-4C alkyl or 6-10C aryl.