to three carbon atoms, R,OR is polyoxyethylene-polyoxypropylene containing at least 6 oxypropylene groups and where the weight ratio of the polyoxyethylene to the polyoxypropylene is not greater than one to four, the total number of oxypropylene groups not exceeding 60, X is a member selected from the group consisting of 1) alkyl and alkenyl containing from one to four carbon atoms, and benzene;