| 摘要 |
1. A process for producing a polyol mixture containing at least two polyols of different molecular weights from the groups of C4 -C6 sugar alcohols and C4 -C6 -anhydrosugar alcohols of the formula see diagramm : EP0058246,P9,F1 in which R**1 is a hydroxyl group or the ether oxygen atom of a second oxacyclopentane ring and R**2 is a hydrogen atom or a hydroxymethyl- or 1,2-dihydroxyethyl group of forms, together with R**1 and the carbon atoms to which R**1 and R**2 are bonded, a second oxacyclopentane ring, provided that at least one polyol of formula 1 is present, by dehydration of C4 -C6 sugar alcohol(s) at a high temperature in the liquid phase and in the presence of a heterogeneous strong acid catalyst, characterized in that converion is effected a) in the presence of water in a quantity which corresponds at least to the water of reaction released on conversion and at most to 120 % by weight, based on the weight of the sugar alcohol (mixture) used, of added water (foreign water), b) at a temperature of between 60 and 2008C, and c) with an (average) reaction time which is so selected that the hydroxyl value of the polyol mixture obtained lies in a range of from 810 to 1800 and the mole ratio of monoanhydrosugar alcohol(s) to sugar alcohol(s) and/or dianhydrohexitol(s) amounts to at least 1 : 9. |
