in which R1 is hydrogen and R2 is a linear or branched carbon radical having from 7 to 28 carbon atoms, or R1 and R2 are each linear or branched carbon radicals having from 1 to 27 carbon atoms, the sum of the carbon number of R1 and R2 being at most 28, to polyol alkyl ethers derived from compounds having at least three hydroxyl functionalities, not more than all but one hydroxyl functionality be