PATENTS

3093.----- [RUHRCHEMIE, A. G.]  [Process for Separating Mixtures of Isomeric Fatty Acids.]  German Patent Appl. --, R 609, filed May 1, 1942.  FIAT Reel K-30, frames 7,702,706; PB 73,587; TOM Reel 36, bag 3,454, item 36, 5 pp.; Meyer Transl. PC-S-IV, Wax Oxidation, vol. 1, ch. 8, 1948, p. 20.

It has been found that when mixtures of fatty acids are saponified, those having straight chains are 1^st reduced then those with slightly branched chains, and lastly those that are more strongly branched.  By incomplete saponification, therefore, mixtures of isomeric fatty acids can be separated in accordance with their degree of branching, and separation of various fractions be made dependent on the extent of the saponification.  The mixture of straight chain or slightly branched saponidied fatty acids on the one hand and thee more extensively branched unsaponified fatty acids on the other hand can be separated in different ways.  For example, the aqueous soap solution can, after the addition of alcohol, be extracted in known manner with benzine.  The fatty acid mixture can also contain unsaponifiable hydrocarbons since these after saponification either separate directly, or insofar as they are dissolved in the soap solution, can be extracted by means of benzine.  In case the fatty acid mixtures contain not only isomeric fatty acids of like molecular magnitude but also acids of different molecular size it is preferable to 1^st separate them by fractional distillation or other suitable means, such as fractional solution or crystallization, into as many narrowly cur fractions of approximately the same size molecules as possible, in order that with incomplete saponification the separation according to isomers is not upset through separation according to molecular size.  This process does not, however, permit of the smooth separation by homologs when isomers are simultaneously present.  The present invention rests on the knowledge that the same mode of action applied under other conditions to mixtures of isomeric fatty acids makes possible a separation of the isomers.  A good separation is, however, only obtainable when no homologs or, in any case, only such homologs are present that are approximately of the same molecular size.  The process is applicable to acid mixtures from any source whatever.  It is especially suitable for acid mixtures whose original C chain was produced during the catalytic hydrogenation of CO, whereby the acid forming carboxyl group was produced either primarily or through direct oxidation or by the catalytic water gas reaction and subsequent oxidation. Gives detailed example of each described method.