This work focuses on the use of a gem-dithiolato-bridged rhodium(I) [Rh 2 (μ-S 2 CBn 2 )(cod) 2 ] complex (cod = 1,5-cyclooctadiene, Bn 2 CS 2 2 = 1,3-diphenyl-2,2-dithiolatopropane) dissolved in toluene in the presence of monodentate phosphite P-donor ligand (P(OPh) 3 ) under carbon monoxide/hydrogen (1:1, syngas) atmosphere as an effective catalyst for hydroformylation of some olefins (oxo-reactions).The capability of this system to catalyze the hydroformylation of hex-1-ene, cyclohexene, 2,3-dimethyl-but-1-ene and 2-methyl-pent-2-ene and their quaternary mixture (synthetic naphtha) has been demonstrated.This innovative method to perform the in situ hydroformylation of the olefins present in naphthas to oxygenated products would be a promissory work for a future industrial catalytic process applicable to gasoline improving based on oxo-reactions.An important observation is that variation of CO/H 2 pressure (6.8 34.0 atm), temperature (60 80 ºC), reaction time (2 10 h), rhodium concentration ((1.0 1.8)x10 -3 mol/L) affect hydroformylation reaction rates.Optimal conversion to oxygenated products were achieved under [Rh] = 1.8 x10 -2 mol/L, P(CO/H 2 ) = 34 atm (CO/H 2 = 1:1) at 80 ºC for 10 h.

The preparation of tetracoordinated copper (I) complexes with the pyrazolyl heterocyclic nitrogen ligand is reported. The new complexes of [Cu(pyrazolyl)(2)] X type with X = chloride, bromine, and iodine were characterized by spectroscopic and electrochemical techniques. The results obtained show that the heterocyclic nitrogen ligand is bonded in a bidentate fashion to form monometallic complexes. Exploratory homogeneous catalysis experiments of the water-gas shift reaction (WGSR) have been accomplished by the use of copper complexes in 80% aqueous 4-picoline solutions. For such systems, formation of H-2 y CO2 was observed in the initial gas samples.

In this work the results of the study of the catalytic activity of the dinuclear gem-dithiolato-bridged rhodium complex [Rh2(μ-S2CBn2)(cod)2] (Bn = benzyl; cod = 1,5-cyclooctadiene) for the hydroformylation of hex-1-ene in CO/H2O, are presented. Under the best conditions for hydroformylation [P(CO) = 22 atm at 80 °C, in 24 h, toluene/H2O = 8/2, v/v, hex-1-ene (3 mmol), [Rh] = 0.01 mmol, hex-1-ene/[Rh] = 15 molar ratio] the only organic products observed (detected by GC and GC-MS) were heptanal and 2-methylhexanal and traces of 2-hexene (isomerization product). In addition, the products of the water gas shift reaction, H2 and CO2, were also obtained as competitive reaction of the hydroformylation process.

The present review describes several examples of the use of soluble and immobilized complexes of rhodium with pyridine ligands as catalysts. Examples include the water-gas shift reaction, the carbonylation of methanol, the reduction of nitroarenes, the hydrocarboxylation and oligomerization of CO/ethylene, the hydrocarbonylation of 1-hexene, the hydroesterification and hydroformylation–acetalization of 1-hexene, the hydrodechlorination of dichloroethane, the carbonylation of naphtha and the hydrogenation and hydroformylation of alkenes.

Rhodium(I) complexes, cis-[Rh(CO)2(amine)2](PF6) (amine = 4-picoline, 3-picoline, 2-picoline, pyridine, 3,5-lutidine or 2,6-lutidine) dissolved in an aqueous solution of tetrabutylammonium hydrogensulfate (N(C4H9)4HSO4), catalyze the water-gas shift reaction (WGSR). The role of the coordinated amine on the catalytic activity was examined.

This work describes the carbonylation of hex-1-ene, cyclohexene, 2,3-dimethyl-but-1-ene and 2-methyl-pent-2-ene, their quaternary mixture and a real Venezuelan naphtha, catalyzed by a rhodium(I) [Rh(cod)(4-picoline)2](PF6) (cod = 1,5-cyclooctadiene) complex immobilized on poly(4-vinylpiridine) (P(4-VP)) in contact with methanol under carbon monoxide atmosphere. The conversion (%) of olefins to carbonylated products for the individual olefins decreases in the order: hex-1-ene (63) > cyclohexene (58) > 2,3-dimethyl-but-1-ene (50) > 2-methyl-pent-2-ene (31), under the following conditions: 0.5 g of P(4-VP) for [Rh] = 2 wt.% (1 × 10−4 mol), 10 mL of CH3OH, [olefin] = 1 × 10−2 mol, S/C = 100, P(CO) = 33 atm at 110 °C for 24 h. Other products such as H2 and CO2 coming from the catalysis of the water–gas shift reaction are observed.

In aqueous solution of tetrabutylammonium hydrogensulfate (N(C4H9)4HSO4), rhodium complexes like cis-[Rh(CO)2(amine)2](PF6) (amine = pyridine, 4-picoline, 3-picoline, 2-picoline, 3,5-lutidine or 2,6-lutidine) promote the carbonylation of 1-hexene to heptanoic acid and heptanal under carbon monoxide atmosphere. Gaseous by-products (H2 and CO2) from the catalysis of the water–gas shift reaction (WGSR) are also observed. The catalytic activities for heptanoic acid and heptanal production depend on the nature of the coordinate amine to the rhodium center for [Rh] = 1 × 10−4 mol, [1-hexene] = 0.05 mol, 40 mL of water (2.2 mol); 2.4 g of N(C4H9)4HSO4 (5.6 wt.%), S/C = 500, P(CO) = 22 atm at 150 °C. Analyses of kinetic results for the Rh/4-picoline system (one of the more active and the most stable catalyst among tested) towards the carbonylation reaction for the organic products formation show a nonlinear dependence on total rhodium concentration and on N(C4H9)4HSO4 amount in the range of studies. The last result suggested that the salty medium stabilize the ionic Rh catalytic species formed under the reaction conditions, therefore enhancing the reactivity. The increase in P(CO) is accompanied by improvement in the catalytic activities of oxygenated products, then reaches a maximum and starts decreasing at higher P(CO). These data are discussed in terms of catalytic cycles bearing a common Rh–H catalytic species.

En este trabajo se describe la catalisis de la hidroesterificacion e hidroformilacion-acetalizacion de 1-hexeno por los complejos de rodio(I) [Rh(cod)(amina)2](PF6) (cod= 1,5-ciclooctadieno; amina= piridina, 2-picolina, 3-picolina, 4-picolina, 3,5-lutidina o 2,6-lutidina) inmovilizados sobre poli(4-vinilpiridina) en contacto con 10 mL de etanol; relacion molar [1-hexeno]/[Rh] = 100; [Rh]= 1x10-4 moles y P(CO)= 0,9 atm a 100°C por 5 h. Los productos mayoritarios son heptanoato de etilo, heptanal y 1,1-dietoxiheptano provenientes de la reacciones de hidroesterificacion, hidroformilacion y la reaccion de adicion nucleofilica de etanol sobre el aldehido formado, respectivamente. La distribucion de los productos de reaccion depende de la naturaleza de la amina coordinada al centro de rodio.

The catalytic reduction of nitrobenzene by rhodium(I) complexes of the type cis-[Rh(CO) 2 (amine) 2 ](PF 6 ) (amine = 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, or 2,6-dimethylpyridine) in methanol under an atmosphere of carbon monoxide is described. A single organic product, aniline, is seen in the post-reaction mixture. The amount of product formed depends upon the nature of the amine coordinated to the rhodium center.

In this work, a mechanistic study of the hydroxycarbonylation of 1-hexene to heptanoic acid and the water gas shift reaction (WGSR) catalyzed by the rhodium(I) complexes, [Rh(COD)(amine)2](PF6) (COD = 1,5-cyclooctadiene, amine = 4-picoline, 3-picoline, 2-picoline, pyridine, 3,5-lutidine or 2,6-lutidine) immobilized on poly(4-vinylpyridine) in contact with water under CO is discussed. Catalytic cycles for these reactions bearing common Rh-H catalytic species are proposed.

The complex, [Rh(COD)(4-picoline)2](PF6) (COD = 1,5-cyclooctadiene), immobilized on poly(4-vinylpyridine) in contact with methanol catalyzes the hydroesterification and hydroformylation-acetalization of 1-hexene to methylheptanoate, heptanal and 1,1-dimethoxyheptane, respectively. The by-product, 1,1-dimethoxyheptane comes from the nucleophilic addition of methanol over the heptanal formed. Also, H2 and CO2 from the water gas shift reaction (WGSR) are observed. The catalytic activity for the hydroformylation and the WGSR proved to be non-linear in the rhodium total concentration range 0.9-5.0 wt.%.

Catalytic activity for reduction of nitrobenzene to aniline (98%) and azobenzene (2%) using a poly(4-vinylpyridine)- immobilized Cu catalyst [Cu(II)/P(4-VP)] under a CO atmosphere in aqueous 2-ethoxyethanol was studied as a function of the various reaction parameters ([Cu], P(CO), T, and nitrobenzene/Cu molar ratio). Reaction rates were first-order in [Cu](tot) over 1.0 - 12.0 wt.% range and in P(CO) over the 6.8 - 27.2 atm range. The catalytic activity proved to be non-linear in nitrobenzene/Cu ratio over 41 - 500 molar ratio range. These results suggest that the rate-limiting step is preceded by reversible coordination of nitrobenzene to a carbonyl - Cu(I) immobilized species. A catalytic mechanism consistent with the data is proposed.

This paper describes the catalytic activation studies of the reduction of some 2-substituted-5-nitrofuran compounds by [Rh(COD)(2-picoline)(2)] (PF6) (COD = 1,5-cyclooctadiene) anchored on poly(4-vinylpyridine) in contact with 80% aqueous 2-ethoxyethanol at 100 degrees C undercarbon monoxide atmosphere. The effect of varying the nature of the 2-substituents of the furan ring was evaluated. The importance of the present catalysis studies can be emphasized, because the potential activity against bacteria of the 2-substituted-5-nitrofuran compounds could be monitored by determining the facility of catalytic reduction of the nitro group.

The formation of transition metal complexes between dichlorocopper(II) and a poly(4-vinylpyridine)/divinylbenzene(2%) polymeric matrix is described in this contribution. The nitrogen atom of the pyridine groups of the organic polymer is coordinatively bonded to the Cu center as suggested by X-ray photoelectron spectroscopy (XPS), UV–vis/diffuse reflectance (UV–vis/DR), electron paramagnetic resonance (EPR), differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) techniques. The immobilized catalyst was also characterized by DTA-TGA analysis and the morphology and elemental analysis of this copper/poly(4-vinylpyridine) complex were studied by the scanning electron microscopy/energy dispersive X-ray (SEM/EDX) technique. This material catalyzes the water gas shift reaction as well as the reduction of nitrobenzene to aniline and azobenzene.

The rhodium(I) complexes, cis-[Rh(CO)2(amine)2](PF6) (amine=pyridine, 2-picoline, 3-picoline, 4-picoline, 3,5-lutidine or 2,6-lutidine) dissolved in methanol under carbon monoxide atmosphere are effective catalysts for the hydroesterification and hydroformylation–acetalization of 1-hexene. In the presence of these soluble complexes, 1-hexene, CO and methanol give methyl-heptanoate and 1,1-dimethoxy-heptane as major products, and minor amounts of heptanal. The acetal product comes from the nucleophilic addition reaction of the methanol with the formed heptanal. Gaseous by-products (H2 and CO2) from the catalysis of the water–gas shift reaction (WGSR) are also observed. The reaction products distribution depends on the nature of the coordinated amine to the rhodium center. The effects of the reaction variables such as CO pressure, temperature, catalyst concentration, 1-hexene/Rh molar ratio and reaction medium, were also examined. These data are discussed in terms of catalytic cycles, and it is concluded that common Rh–H catalytic species are involved.

The hydrodechlorination of chlorobenzene to benzene and biphenyl was studied using poly(4-vinylpyridine)-immobilized Cu catalysts under CO in basic (NaOH, N(C2H5)3 or Na(CH3CO2)) aqueous 2-ethoxyethanol medium. This Cu system also catalyzed the water gas shift reaction. The catalytic activities for hydrodechlorination of chlorobenzene to benzene were studied as functions of the reaction parameters (nature of the base, reaction time, [Cu], P(CO), T, and S/C). Among the different base studied activity is maximum for NaOH. The rate of benzene formation displays a first-order dependence on [Cu] over the range 1.25–12.50 wt%. This observation was interpreted in terms of the presence of active species having the same nuclearity. The catalytic activity towards benzene formation proved to be first order dependence on P(CO) over the range 5–35 atm. The kinetics behavior with respect to P(CO) leads to the proposal that CO addition to the catalytic species precedes the rate-limiting step. The catalytic activity proved to be non-linear in chlorobenzene/Cu content, over the range 50–400 molar ratio. The results suggest that the rate-limiting step is preceded by reversible oxidative addition of chlorobenzene to Cu immobilized species.

This work describes the catalytic hydroesterification and hydroformylation of 1-hexene by [Rh(cod)(amine)2](PF6) complexes (cod=1,5-cyclooctadiene; amine=pyridine, 2-picoline, 3-picoline, 4-picoline, 3,5-lutidine or 2,6-lutidine) immobilized on poly(4-vinylpyridine) in contact with methanol under carbon monoxide atmosphere. In the presence of these immobilized complexes, 1-hexene, CO and methanol give methyl-heptanoate and 1,1-dimethoxy-heptane as the main reaction products and minor amounts of heptanal. The acetal by-product comes from the nucleophilic addition reaction of the methanol with the formed heptanal. Other products, such as H2 and CO2 coming from the catalysis of the water–gas shift reaction are observed. The reaction products distribution depends on the nature of the coordinated amine to the rhodium center and the reaction parameters.

The catalysis of the hydroesterification and hydroformylation-acetalization of 1-hexene by rhodium(I), cis-[Rh(CO)2(amine)2](PF6) complexes (amine = pyridine, 2-picoline, 3-picoline, 4-picoline, 3,5-lutidine or 2,6-lutidine) dissolved in 10 mL of ethanol or 10 mL of 80% aqueous ethanol, 0.4 mL (3 x 10-3 mol) of 1-hexene, [Rh] = 5 x 10-5 mol, 1-hexene/Rh = 64 under P(CO) = 0.9 atm at 100 °C for 4 h, is described in this work. The mayor products are ethyl-heptanoate, heptanal and 1,1-diethoxyheptane coming from the hydroesterification, hydroformylation reactions and the nucleophilic addition reaction of the ethanol over the formed heptanal, respectively. The reaction product distribution depends on the nature of the coordinate amine to the rhodium center

Summary Rhodium(I) complexes, [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) immobilized on poly(4-vinylpyridine) in contact with water catalyzed both the hydroxycarbonylation of 1-hexene to propionic acid and the water-gas shift reaction (WGSR). The role of the coordinated amine on the catalytic activity was examined.

Rhodium(I) complexes of the type, cis-[Rh(CO)2(amine)2](PF6) where (amine = 3-picoline, 2-picoline, pyridine, 2,6-lutidina or 3,5-lutidine) dissolved in 80% aqueous amine solutions catalyzed the selective reduction of 4-nitrobenzoic acid to 4-aminobenzoic acid under CO atmosphere. The importance of these catalytic systems is their high chemo selectivity for the aromatic nitro group of the 4-nitrobenzoic acid with respect to the carboxylic group, allowing the production of the desired aromatic amine in high yields. The 4-aminobenzoic acid production depends on the nature of the coordinated amine. The Rh/3,5-lutidine system, the most active catalyst among tested, displays turnover frequencies for 4-aminobenzoic acid production of about 173 moles per mole Rh per day for [Rh] = 1 × 10−4 mol, [4-nitrobenzoic acid] = 3.82 × 10−3mol, 10 mL of 80% aqueous 3,5-lutidine, P(CO) = 0.9 atm at 100 °C. Analyses of kinetic results for the Rh/3,5-lutidine system show a first order dependence on 4-nitrobenzoic acid concentration, a non-linear dependence on CO pressure, a segmented Arrhenius plot and dependence on the nature of the reducing gas agent. These data are discussed in terms of a possible mechanism.