The reduction of nitrobenzene as catalyzed by poly(4-vinylpyridine)-immobilized [Rh(COD)(amine) 2](PF 6) complexes under WGSR conditions

• Published in: Journal of molecular catalysis. A, Chemical Chemical, 2000-12, Vol.164 (1), p.225-234
• Main Authors: Pardey, A.J, Fernández, M, Alvarez, J, Urbina, C, Moronta, D, Leon, V, Longo, C, Baricelli, P.J, Moya, S.A
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts: preparations and properties; Chemistry; Exact sciences and technology; General and physical chemistry; Nitrobenzene; Poly(4-vinylpyridine); Rhodium complexes; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; WGSR; XPS
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/S1381-1169(00)00264-8

Catalysts for the selective reduction of nitrobenzene to aniline prepared from poly(4-vinylpyridine) (P(4-VP))-immobilized [Rh(COD)(amine) 2](PF 6) (COD=1,5-cyclooctadiene, amine=4-picoline, 3-picoline, 2-picoline, pyridine, 3,5-lutidine or 2,6-lutidine) complexes in contact with 80% aqueous 2-ethoxyethanol, 1×10 −4 mol Rh/0.5 g of polymer, 0.9 atm of CO pressure at 100°C under water–gas shift reaction conditions (WGSR, CO+H 2O⇄CO 2+H 2) are described. Aniline production (milimole/3 h) depends on the nature of the amine and decreases in the following order: 2-picoline (0.65)>4-picoline (0.59)≥3-picoline (0.56)>pyridine (0.49)>3,5-lutidine (0.38)>2,6-lutidine (0.34). The immobilized [Rh(COD)(2-picoline) 2](PF 6) complex was found to be reusable as a catalyst for the title reaction. The Rh/2-picoline complex was immobilized to the pyridine groups of the organic polymer as supported by Fourier transform infrared (FT-IR), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), UV/Vis/diffuse reflectance (DR) spectroscopies, and scanning electron microscopy (SEM) studies.