Application of urea complexes in the purification of fatty acids, esters, and alcohols. II. Oleic acid and methyl oleate from olive oil

Abstract

SummaryOleic acid and methyl oleate of high purity (97–99%) and substantially free (0.2% or less) of polyunsaturated contaminants have been isolated in 60–70% yield from the fatty acids or methyl esters of olive oil by procedures which require only one precipitation of urea complexes (single dose of urea technique) one low‐temperature crystallization, and one fractional distillation. The best yields of the highest purity acids are obtained when saturates are removed by fractional crystallization prior to a final distillation. The urea complex separation technique can be applied directly to olive oil methanolysis reaction mixtures without prior isolation of the mixed methyl esters.Oleic acid or methyl oleate obtained by decomposition of urea complexes contains approximately 1% of polyunsaturated contaminants. After fractional distillation or crystallization to separate saturated acids the oleic content is about 90–97%. Such products are satisfactory for many uses and in their preparation low‐temperature (−50° or lower) crystallizations are not required.Solution and slurry techniques have been studied for the preparation of urea complexes from olive oil acids or esters. The former technique is preferred when a maximum of about 1,000 grams of acids or esters are to be processed. The latter is preferred for larger size experiments mainly because the volume of methanol employed is cut in half, the time is shorter, and also because yields are about 5% higher.