LABORATORY AND PILOT-PLANT SYNTHESIS OF A REFERENCE RAMIFIED FATTY-ACIDS TRIGLYCERIDE

About 500 grams of triisopalmitin pure at 90% in triglyceride and 95% in isopalmitic acid have been prepared in 100 gram batches by Wittig p rocess from 11-bromoundecanoic acid and isovaleraldehyde. This synthes is requires six steps : (1) methylation of 11-bromoundecanoic acid; (2 ) production of phosphonium salt by addition of triphenylphosphine to methyl 11-bromoundecanoate; (3) synthesis of methyl 11-methylpentadece n-11-oate by reaction of a-carbomethoxyundecamethylene-triphenylphosph onium bromide with a strong base to produce omega-carbomethoxyundecyli denetriphenyl-phosphoran followed by addition of isovaleraldehyde; (4) hydrolysis of methyl 14-methylpentadecen-11-oate; (5) hydrogenation o f 14-methylpentadecen-11-oic acid; (6) synthesis of triisopalmitin by glycerolyse of isopalmitic acid. 1.5 kg bromoundecanoic acid is necess ary for the production of two 100 g batches of triisopalmitin; this co rresponds to a 75% molecular yield after purification of the triglycer ide. Because of the important quantities of reactives, the three first steps of the synthesis have been processed on a pilot scale. For this transposition such techniques as liquid/liquid or liquid/solid extrac tion and fractional or flash distillation have been employed for the p urification of the intermediate reaction products. The second and thir d reaction steps are essential to obtain a very high pure isopalmitic acid.