Amido-Imidol Tautomerization by Acid-Catalyzed Addition of Nitriles to 16-Hydroxyhexadec-cis-9-enoic Acid: A Novel Route for 9-[Substituted Amido]-16-ol-hexadecanoic Acids, and Their Biological Importance and Possible Industrial Utilization

Considering the extensive applications of oleochemicals as industrial products, a series of novel 9-[substituted amido]-16-olhexadecanoic acids have been synthesized by the reaction of different nitriles with 16-hydroxyhexadec-cis-9-enoic acid. The specific nitriles, including acetonitrile, propionitrile, (beta)-methoxypropionitrile, (beta)-ethoxypropionitrile, (beta)-(2ethoxy)ethoxypropionitrile, (beta)-butoxypropionitrile, (beta)-amyloxypropionitrile, (beta)-isoamyloxypropionitrile, ethylcyanoacetate, o-carboxyphenylacetonitrile, benzonitrile, and benzyl cyanide, were added to the double bond of 16hydroxyhexadec-cis-9-enoic acid in the presence of concentrated sulfuric acid followed by hydrolysis. The mechanism of acid-catalyzed addition of nitriles to 16-hydroxyhexadec-cis-9-enoic acid has been confirmed by its amido-imidol tautomerization. Thus, the addition of nitriles at carbon-9, instead of carbon-10, of 16-hydroxyhexadec-cis-9-enoic acid has been confirmed by mass spectral fragmentation of McLafferty rearrangement due to the secondary amide group, which showed molecular ion peaks at m/z 144 in all of the compounds. Further, these newly synthesized oleochemicals have been studied and characterized by FTIR, 1H NMR, and 13C NMR spectroscopies; MS; and elemental analyses.