Journal of M olecular zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Catalysis, 83 (1993) 51-65 Elsevier Science Publishers B.V., Amsterdam 51 Ml20 Hydroformylation of cy- and /3-pinene catalyzed by rhodium and cobalt carbonyls zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFED Eduardo N. dos Santos Instituto de Quimica Universidade Estadual de Campinas, C. Postal 6154,13081 Campinas, S&o Paul0 (Brazil) Charles U. Pittman, Jr.* and Hossein Toghiani Departments of Chemistry and Chemical Engineering, Mississippi State University, Mississippi State, MS 39762 (USA); tel. (+ l-601)3257616, fax. (+ l-601)325761 1 (Received September 14,1992; accepted February 3,1993) zyxwvutsrqponmlkjihgfedcbaZYXWVU Abstract cy- and/%Pinene were hydroformylated to their respective aldehydes and alcohols at 60-130°C and 600 psi of CO/H,. Employing Rb(CO) i6 as a catalyst precursor the main product is lo- formylpinane, 2. In contrast, mononuclear rhodium complexes containing phosphine ligands typ- ically give 3-formylpinane, 1, as the major product. 3-Formylpinane, 1, was also the main product upon employing either Coz (CO), or phosphine-modified &(CO),,. The turnover frequency drops sharply as the total rhodium concentration increases upon using Rh, (CO) i6 to catalyze cu-pinene hydroformylation at 130°C and 600 psi of H&O (1: 1). This shows that cluster fragmentation occurs to generate the active catalytic species of lower nuclearity. Furthermore, the product dis- tribution at equivalent cu-pineneconversions remains the same at different total rhodium concen- trations under Rh, (CO) i6 catalysis, suggesting there is only (predominantly) one catalytically active species operating in the reaction. Hydroformylation with triphenylphosphite-modified Rha( CO)ia was initially faster but the catalyst life is short due to hydrogenolysis of triphenyl- phosphite which produces phenol. Hydrogenation of (Y- and 8-pinene (Pd/C, 1 atm Hz, ambient temperature) generated the two pinane isomers, 10 and 11, which result from the hydrogen addition to the two faces of the double bond. The only hydrogenation byproduct detected during Rh, (CO ),s-catalyzed hydroformylations was 11 where hydrogen addition occurred to the face of the double bond which was cis to the C (CH,), bridge. Use of the mixed metal carbonyl systems: Co,(CC),/Rh,(CC),,, Co,(CO)s/Ru,(CO),~, Rhe(CO),,/Ru,(CO),,/PPh, and Coz(CC)i2/ Rhe( CO),,/PPha in toluene at 100°C and 600 psi Hz/CO= 1: 1 did not lead to any synergistic rate enhancements in the hydroformylation of cy-pinene. Key words: cobalt carbonyl; formylpinenes; hydroformylation; hydrogenation; mixed metal clusters; phosphines; phosphites; pinenes; rhodium carbonyl; ruthenium carbonyl Introduction The hydroformylation of terpenes is an important pathway for the syn- thesis of aldehydes of interest in the perfume industry [ 11. A series of terpene *Corresponding author. 03045102/93/$06.00 0 1993 - Elsevier Science Publishers B.V. All rights reserved.