Dimerization of oleic acid with a montmorillonite catalyst. I. Important process parameters; some main reactions

Some process parameters, e.g., amt. of catalyst, water content, stirring intensity, reaction time, and pH of the catalyst were examd. in the dimerization of oleic acid with montmorillonite as the catalyst. A yield limit existed at .apprx.60% (dimers and trimers). The remaining 40% of the reaction mixt. (monomers) contains only small amts. of cis- and trans-monounsatd. fatty acids, the remainder being unidentified products, which can hardly be dimerized and cannot be hydrogenated with Pd on C. The ir spectra of these monomers reveal also the presence of small amts. of g-stearolactone and an increase in the no. of Me groups, which is probably the result of skeletal isomerization, although structures such as CH:CMe are absent. The result indicate that a fairly large amt. of satd. fatty acids is formed probably by H transfer. According to this assumption, dienoic acids must be formed, which are readily dimerized to cyclic dimers. Thus, the common assumption that the dimers of oleic acid obtained by this process are noncyclic becomes improbable.