Ru Supported Catalysts Testing in the Preparation of p-Isopropylcyclohexylmethanol

It is known that p-isopropylcyclohexylmethanol (CAS# 13828-37-0) is a desirable compound in the fragrance industry, featuring a green, floral, petaly, magnolialike, tuberose and muguet odor profile. It occurs in two isomers, cis and trans, whose olfactory properties differ insignificantly. For the preparation of perfumes, the ratio 70:30 (cis:trans), commercially named Mayola, is usually used. The preparation of Mayol most often starts with b-pinene. This procedure starts by epoxidation of pinene, followed by ring-opening with the intermediate perillyl alcohol, which is finally hydrogenated (Ra-Ni) to p-isopropylcyclohexylmethanol. Another possibility for its preparation is the formation from perillyl acetate (prepared from β-pinene oxide and acetic anhydride) and perillyl alcohol. The final step of this preparation was again hydrogenation (Ni/Al2O3). Perillyl alcohol is an intermediate for the hydrogenation, which was also prepared from b-pinene oxide using the catalytic system pyridinium nitrate—nitric acid. p-Isopropylcyclohexylmethanol can be prepared directly from p-cymene by electrochemical methods.

The preparation of p-isopropylcyclohexylmethanol by direct hydrogenation of cuminaldehyde is also described in the literature. In these patents, the addition of solvents to cuminaldehyde was suggested, and an Ru/C catalyst was used. Another possibility offered by literature is the use of Ru supported on alumina or silica.Separation of the cis and trans isomers from the reaction mixture is also possible.

Due to the accessibility of the information about hydrogenation of cuminaldehyde only in the patent form, the study of the influence of reaction conditions (solvent type, temperature, pressure) on the selectivity to the desired p-isopropylcyclohexylmethanol was performed in this work. The authors would like to also offer insights to the range of possible Ru/C catalysts.

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