Regio selectivity in the hydrogenation of geraniol over platinum containing zeolites

Tuning Selectivity in Terpene Chemistry: Selective Hydrogenation versus Cascade Reactions over Copper Catalysts

“…Rh-and Ru-based catalysts have been predominately utilized, Noyoris BINAP ligand being the most frequently used. [5] As far as heterogeneous catalysts are concerned, the earliest literature for the preparation of citronellol from geraniol reported the use of Pt black or Pt oxide and Ni, [6] while more recent papers report on the use of more complex catalytic systems such as platinumcontaining zeolite, [7] Pt/Al 2 O 3 modified with carboxylic acids, [8] Ni/diatomaceous earth and alkali hydroxides or carbonates [9] or Raney Ni and alkali or alkaline earth metal hydroxides. [10] In these studies yields never exceeded 85%.…”

Support Effects in Nerol Hydrogenation over Pt/SiO2, Pt/H-Y and Pt/H-MCM-41 Catalysts

“…Citronellal has been hydrogenated to citronellol with the selectivities up to 90% over Ru/TiO 2 catalyst [6]. Very high selectivities for C (94%) have been reported in geraniol hydrogenation over pt/Y in toluene [8]. The only products were C and D. Hydrogenation of nerol over Pt/SiO 2 in hexane has been reported in literature [2].…”

“…It can be synthesized by several methods, for instance catalytic hydrogenation starting from citral [5], citronellal [6,7], nerol [3] or geraniol [8], or hydrodealumination of the alumino-derivative of dihydromyrcene followed by oxidation and hydrolysis [9] or via treating an acyclic terpene with NaBH 4 and AlCl 3 with further hydration and oxidation with H 2 O 2 [10]. Furthermore C can be prepared via pyrolysis of pinane followed by hydration [11].…”

“…Metal supported, mesoporous H-MCM-41 is a potential support material for chemoselective hydrogenations [8,[15][16][17][18], because of its large specific surface area and larger pores than zeolites. MCM-41 has recently been used as support in the hydrogenation and cyclization of citral to menthols over Ni/Al-MCM-41 [15], geraniol over Pt/MCM-41 [8], cinnamaldehyde over Ru-MCM-41 [16,17] and prostaglandin intermediates over Ru-MCM-41 [18].…”

“…MCM-41 has recently been used as support in the hydrogenation and cyclization of citral to menthols over Ni/Al-MCM-41 [15], geraniol over Pt/MCM-41 [8], cinnamaldehyde over Ru-MCM-41 [16,17] and prostaglandin intermediates over Ru-MCM-41 [18]. In geraniol hydrogenation at 80°C and 20 bar in toluene over Pt/MCM-41 the selectivities to citronellol were high, 85%; the only other product was 3,7-dimethyloctanol [8]. The catalyst used in the work of Tas et al [8] was prepared via impregnation of MCM-41 with Pt(NH 3 )Cl 2 .…”