Abstract: The reductive cleavage of linear and cyclic acetals, especially formals, in an aqueous medium containing a formate takes place by hydrogenation with hydrogen in the presence of a heterogeneous hydrogenation catalyst at a pH value of less than 7 at a temperature of over 200° C. The catalyst-poisoning effect of the formate is overcome at over 200° to 300° C., especially from over 200° to 280° C., so that, in a suspension procedure, the weight ratio of metal having hydrogenating activity to acetal is less than 0.1.

Abstract: The acid-catalyzed intermolecular etherification of mono- or polyhydric alcohols and acid-catalyzed ether cleavage in the presence of water may be improved if etherification or ether cleavage is carried out in the presence of an acid catalyst and, additionally, a hydrogenation catalyst under a hydrogen atmosphere. The process relates in particular to the etherification of diols, triols and tetrols with the formation of hydroxyethers.

Abstract: A process for producing polyhydroxy ethers having the formula (I) (HO).sub.(w--M) W(OV).sub.m, in which W represents an organic group and OV a structural element containing hydroxyl groups, having the formula (III) ##STR1## A multifunctional alcohol W(OH).sub.w (II) is reacted with an .alpha.,.beta.-unsaturated carbonyl compound XCH.dbd.CY--CZ.dbd.O (IV) and formaldehyde in the presence of a base. The .alpha., .beta.-unsaturated carbonyl compound (IV) and the remaining quantities of formaldehyde, multifunctional alcohol (II) and base are added continuously or periodically to an aqueous solution or suspension containing at least 10 mole % of the multifunctional alcohol (II), at least 10 to 70 mole % of the formaldehyde and at least 10 mole % of the base. Preferred multifunctional alcohols (II) are pentaerythritol, TMP and TME. Preferred carbonyl compounds (IV) are acrolein and .alpha.-alkylacrolein. New asymmetric polyhydroxy ethers are also disclosed.

Abstract: The present invention relates to a process for the production of five-membered or six-membered cyclic ethers, in particular of anhydropolyols, by acid-catalysed cyclodehydration of polyols that contain at least two hydroxyl groups with a spacing enabling ring formation--that is to say, preferably with a spacing of 4 or 5 C atoms. The invention is directed in particular towards the production of anhydrotetritols, anhydropentitols and, particularly preferred, anhydrohexitols, from tetritols, pentitols and hexitols, respectively.