Partial hydrogenation of linseed oil by a continuous process

Summary Alkali refined linseed oil was partially hydrogenated, using both continuous and batch processes. The continuous process was carried out in a series of Votator machines, using Rufert nickel catalyst, presures up to 145 psig. and temperatures up to 400°F. The continuous hydrogenation of linseed oil under the most selective conditions possible, using the Votator equipment, shows little selectivity between the linolenic and linoleic acid radicals. A pronounced selectivity is observed between oleic and the more unsaturated acid radicals. Under selective conditions of hydrogenation of linseed oil about 31% of the hydrogenated linolenic acid radical is transformed into 9–15 linoleic acid while the remainder of the linolenic acid goes to oleic acid in either one or two steps. Batch hydrogenation yields oils of superior nonyellowing characteristics over comparable oils prepared by the continuous process. The hydrogenated linseed oils were tested in both clear and pigmented alkyds where they displayed superior non‐yellowing characteristics over the original linseed oil and, in many instances, over that of soya bean oil. The yellowing of oils and alkyds appears to be a function of both 1) the quantity of fatty acids more unsaturated than oleic present in the oil and 2) the ratio of the quantity of linolenic acid radicals to linoleic acid radicals present.