as usual the solvent is then recycled if much olefinic hydrocarbon is present in the feedstock it will tend to transfer to the aromatic solvent layer on distillation of the aromatics from this extract the olefins tend to polymerize and build up in the solvent since the solvent cannot be distilled as in the conventional solvents it must be periodically purified in other ways one way is to run the contaminated solvent over a charcoal bed which absorbs the polyolefins another way is to add water to the contaminated solvent the solvent dissolves in the water and the polyolefins will separate an an insoluble phase water is then distilled from the purified solvent and the solvent recycled if desired for economic reasons 5 water may be left in the solvent and recycled to the extraction column a series of glycerine ethylene oxide triols were prepared by reacting varying amounts of ethylene oxide with glycerine using 0 1 potassium hydroxide as the catalyst at a temperature of 100 u00b0 c for 8 hours these compounds are complex mixtures having on each hydroxyl radical one or more ethylene oxide adducts they are further described in table i table i______________________________________glycerine ethylene oxide triols number averagee o triols moles eo mol wt gpc oh______________________________________control 1 3 190 22 6example 1 6 290 13 6example 2 9 420 9 7example 3 12 590 7 5example 4 15 690 6 3example 5 18 850 5 4______________________________________ gpc determined by gel permeation chromatography aromatic capacity and selectivity values were determined for each solvent of examples 1 5 by extracting stock solutions of 50 benzene 50 heptane and 50 xylenes 50 heptane with the solvents in.