Rosaphen synthesis: homogeneously catalyzed aldol condensation of cinnamaldehyde or hydrocinnamaldehyde with propanal followed by hydrogenation over ruthenium and nickel supported catalysts

2-Methyl-5-phenylpentan-1-ol, commercially known as Rosaphen, is a fragrance used in the perfume and cosmetics industry for its scent of fruits and flowers. This work is focused on its two-step synthesis. At the first step, aldol condensation of cinnamaldehyde and propanal was carried out. The influence of used catalyst, reactants molar ratio, type, and amount of solvent was investigated. The most suitable conditions were the molar ratio of the starting materials equals 1:1, 36% aqueous solution of NaOH at the 0.1:1 molar ratio to cinnamaldehyde and methanol in a molar ratio of cinnamaldehyde to methanol of 1:13. Resulting 2-methyl-5-phenylpenta-2,4-dienal was hydrogenated using different Ru/C and Ni/SiO2 catalysts. The influence of catalyst type and amount, reaction temperature, and hydrogen pressure on the reaction course was studied. Rosaphen in concentration about 97% in final reaction mixture was obtained using hydrogen pressure 10 MPa, temperature 120 °C, and 10 wt% of Ni/SiO2 catalyst.