A High (Z)/(E) Ratio Obtained During the 3-Hexyne Hydrogenation with a Catalyst Based on a Rh(I) Complex Anchored on a Carbonaceous Support

Abstract

The (Z)/(E) ratio was analyzed for the 3-hexyne semi-hydrogenation at 275, 290 and 303 K. [RhCl(NH 2 (CH 2 ) 12 CH 3 ) 3 ] pure and supported on a carbonaceous material were used as catalysts. The supported complex showed high values of conversion and selectivity, and its behaviour was much better than the Lindlar catalyst used as a reference.

Graphite oxide as a support for palladium and rhodium complexes, assessed as catalysts for the partial hydrogenation of 1-heptyne

“…The reader can find a more detailed information of these coordination compounds in published papers. 16,17 From elemental analysis Pd:Cl:N = 1:2:2 and Rh:Cl:N = 1:1:3 molar ratios can be confirmed. XPS spectra interpretation confirmed the following oxidation states: ca.…”

“…11,12 Besides, transition metal complexes are widely used as catalysts for homogeneous and heterogeneous hydrogenation reactions, presenting the advantages of higher activities and selectivity's even under mild conditions. [13][14][15][16][17] In the last decade, different transition metal complexes of Co, Cu and Rh with different ligands anchored on GO, have been tested for oxidation or reduction reactions. [18][19][20][21] There are few publications on transition metal complexes supported on GO as catalysts for the partial hydrogenation of medium chain terminal alkynes.…”

Terminal and Non Terminal Alkynes Partial Hydrogenation Catalyzed by Some d8 Transition Metal Complexes in Homogeneous and Heterogeneous Systems

“…XPS binding energies for the pure substances are in accordance with the literature values [50,51]; showing that Pd or Rh, N and Cl are present in the corresponding products obtained after the synthesis and purification stages. Besides, the electronic states of these atoms may be considered as follows: a) n+ for Pd or Rh, with n = 2 and n close to 1 respectively; this is based on data in Table 2 and the literature values 338.3 eV for [PdCl2(NH3)2] and ranging from 307.3 to 308.5 eV for Rh(I) [50,51]; b) -3 for N but as an ammonium-like nitrogen as the 1s binding energies in Table 2 fall within the values found in the literature (400.9 to 402 eV [50,51]) corresponding to a NH4 + species; this information suggests a bonding character for the N lone pair towards an electrophilic centre, in this case the Pd or Rh atom; and c) -1 for Cl as in a chloride compound because the 2p3/2 binding energies in pure [49] 338.2 401.9 198.3 2.00 1.99 --Al2O3 fresh [49] 338 [49] 338 [53] 338. pure [49] 307.1 402.1 198.1 3.00 1.01 --Al2O3 fresh [49] 307 [49] 307 [52] 307 On the other hand, Figure 1 shows the pure TDA, [PdCl2(TDA)2] and [RhCl(TDA)3] FTIR spectra, while Figure 2 depicts the pure [PdCl2(TDA)2] IR spectrum in the range below 600 cm -1 . As observed at high wavenumbers in Figure 1, the following characteristic peaks of a primary aliphatic amine [44], are present: (A) NH2 "stretching" (3600-3100 cm -1 ), CH "stretching" (3000-2800 cm -1 ), (B) NH2 "bending" (1700-1600 cm -1 ), CH "bending" (1500-1300 cm -1 ) and (C) CN "stretching" (1200-1000 cm -1 ).…”