GB558881A - - Google Patents

Abstract

558,881. Modified fatty acids and fatty oils. STEVENS, A. H. (American Cyanamid Co.). Oct. 15, 1941, No. 13286. [Class 91] [Also in Group IV] Polyunsaturated higher fatty acids containing at least two and preferably non-conjugated double bonds are isomerised to bring about a substantial content of conjugated double bonds therein by heating an aqueous solution of their soaps and an excess of alkali in a closed chamber at temperatures of about 200‹-250‹ C. and under the corresponding autogenic pressure. The process may be applied directly to oils containing the glycerides of such acids, such as oils of iodine number of at least 110 e.g. vegetable and fish oils. Linseed, soya bean, and cottonseed oil are specified amongst others. The process may be applied to such acids in which a proportion of the double bonds are already in the conjugated position, the products obtained containing an increased proportion thereof e.g. dehydrated castor oil fatty acids. The process is not advantageous with eleostearic acid or oils containing its glycerides, such as tung or oiticica oil. The isomerised fatty acids are liberated from their soaps, such as by acidifying with HCl, and these acids may then be re-esterified with a polyhydric alcohol containing at least three esterifiable hydroxy groups, such as glycerol, pentaerythritol, or dipentaerythritol, to give improved drying oils. The content of polyunsaturated fatty acids in the initial fatty acid mixture, e.g. soya bean fatty acids may be increased by preliminarily separating out the more saturated fatty acids, stearic acid &c. such as by cooling the mixture and filtering off the crystallized saturated acids. The content of conjugated double bond fatty acids may also be increased by vacuum distillation of the isomerised fatty acid mixture to give fractions richer in conjugated acids. In the numerous examples given starting with the fatty acid mixtures specified above, isomerised fatty acid mixtures are obtained containing substantial proportions of 9, 11-octadecadienic acid 1 and 10, 12, 14-octadecatrienic acid. Besides caustic soda and caustic potash, lithium hydroxide is specified for effecting the isomerisation. The isomerised fatty acids may be used for preparing modified alkyd resins by heating mixtures of phthalic anhydride, glycerine and the isomerised acids, the acids specified comprising isomerised linseed fatty acids, isomerised soya bean fatty acids, and isomerised fish oil fatty acids respectively. Specification 561,803 is referred to. Reference has been directed by the Comptroller to Specification 561,803.