N-octenyl succinimide of tetraethylene pentamine was prepared by placing one mole of the amine in a reaction flask fitted with an addition funnel containing one mole of n-octenyl succinic anhydride, a water collector, a stirring and heating means and a reflux condenser. While the amine was stirred, the anhydride in the funnel was slowly added to the flask. Upon completion of the addition, the resulting reaction mixture was heated to about 142° C., whereupon water of reaction started to distill over. AT about 180° C., the resulting reaction product, viz., n-octenyl succinimide of tetraethylene pentamine, was a clear bright orange liquid. About one mole of water was collected in the collector, signifying that the imide-forming reaction was complete. The flask and its contents were then cooled to about 80° C., and sufficient isopropanol and distilled water were added to yield a solution which was 40 volume percent isopropanol, about 60 volume percent water and about 30 weight percent amide. Into this solution, based upon the total weight of the solution, about 1 weight percent mono-9-octadecenoate of poly (oxy-1,2-ethanediyl) sorbitol (about 20 ethanediyl groups) surfactant was added to facilitate effective dispersion of the imide agent when added to cooling water. The flask and its contents were maintained at about 80° C. with stirring until a clear solution resulted. The cooled solution was ready for use in accordance with the invention.
