Surfactant Aided Reductive Carbonylation of Nitrobenzene inWater Catalyzed by Pd Complexes

The catalytic carbonylation of nitroarenes is a field of high interest from a technological point of view, since provides an environmentally benign route to a number of important industrial products, such as isocyanates, carbamates, ureas, azoarenes and azoxyarenes, amines, amides, oximes and several types of heterocyclic compounds. The reductive carbonylation of nitrobenzene in water carried out by using Pd(II)-solvable catalyst precursors, leads to aniline, as major product. In the present paper we propose the micellar catalytic reductive carbonylation of nitrobenzene in water. The Pd(II) catalyst precursors tested are synthesized by using cheaper commercial insolvable ligands, such as triphenylphosphine (PPh3), 1,3- bis(diphenylphosphino)propane (dppp) and 1, 10-phenantroline (phen). The influence on the conversion and on the selectivity of such precursors has been evaluated in combination with commercial anionic (SDS), cationic (TBAB) and non ionic (Triton X 100) surfactants. We have found that all the Pd(II) complexes tested are efficiently dissolved in each O/W emulsions but the conversion is strongly influenced by the nature of ligand. By using Pd(OAc)2(PPh3)2, high selectivity towards azo- and azo-oxybenzene has been obtained. The influence of some reaction parameters has been further evaluated and optimized

Pd(II)-catalyzed emulsion copolymerization of carbon monoxide with ethene in CH2Cl2/water as a solvent

Chemical, physical and mechanical characteristics of alt poly(1-oxo-trimethylene) [1] well fit with a wide range of industrial applications and recently several researchers have shown a renovated keen interest for the application of such a polymer in the field of fibers [2]. In order to obtain fibers, however, high molecular weight polymers are required. In some papers we have reported that high molecular weight polymers require high pressure and low temperature but the nature of the solvent must be considered too [2-4]. The choose of the solvent influences both the activity of the catalyst and the average molecular weight of the polymer. Usually the catalysis is efficiently carried out in methanol by using the [Pd(OAc)2(DPPP)] complex in the presence of an acid (p-toluenesulfonic, TsOH) [5] which leads to polymers with not so high average molecular weight. By replacing methanol with CH3COOH-water also [PdCl2(DPPP)] complex efficiently catalyzes the reaction leading also to an increase of the polymer molecular weight [3]. By continuing the research on the influence of the solvent on the molecular weight, here we report our preliminary results on the preparation of alt- poly(1-oxo-trimethylene) by emulsion catalytic polymerization. The [PdCl2(DPPP)] complex has been dissolved in a CH2Cl2-H2O emulsion and the productivity has been optimized

The catalytic copolymerization of ethene with carbon monoxide efficiently carried out in water/dichloromethane/sodium dodecylsulfate emulsion

The CO-ethene copolymerization has been efficiently carried out in the water/CH2Cl2 emulsion by using water insolvable Pd(II) complexes. By using the surfactant SDS very high molecular weight copolymers have been obtained with high productivity (ca. 13,000 g/(gPd.h))

Environmentally friendly corrosion inhibitor of the copper in 0.5 M sulphuric acid solution.

Environmentally friendly corrosion inhibitor of the copper in 0.5 M sulphuric acid solution. G. Quartarone,a L. Ronchin,a A. Vavasori,a C. Tortato,a L. Bonaldo.b aUniversity of Venice, Dep. of Chemistry, Dorsoduro. 2137, 30123 Venice. E-mail: [email protected] bLubrikn, production of additives for lubricant, via Dell’Artigianato, 38, 30030 Vicenza. Copper corrosion inhibition by gramine [3-(dimethylaminomethyl)indole] in the 0.5 M sulphuric acid solutions was studied in the temperature range 25-55 °C using electrochemical impedance spectroscopy techniques (EIS). Gramine was dissolved at various concentrations (from 5∙10-4 to 7.5∙10-3) in 0.5 M sulphuric acid. The surface preparation of the specimens was carried out using silicon carbide paper up to grade 1200. EIS measurements were performed after dipping the working electrode into the 0.5 M sulphuric acid solutions with or without inhibitor at Ecorr with an a.c. voltage amplitude of 5mV. The frequency range was swept between 100 kHz and 10 mHz with 10 point for hertz decade. The presence of gramine led to changes of the impedance plots in both shape and size. The plots of Nyquist exhibited that some impedance spectra consisted of one capacitive loop at the higher frequencies which was attributed to a faradaic process involving a charge transfer resistance in parallel with double-layer capacitance element [1]. The size of the capacitive arc increased by increasing the concentration of gramine. This indicated that gramine increased the charge transfer resistance and then it had an inhibiting effect on copper corrosion in 0.5 M sulphuric acid solutions. Inhibition efficiencies results showed that the gramine inhibited the copper corrosion in the temperature range 25-55 °C reaching the maximum value of 86% at 55 °C. Impedance spectra also showed a depression of Nyquist-plot semicircles that can be related to the surface heterogeneity due the microscopic roughness of the electrode surface and inhibitor adsorption [2]. Moreover at the lower frequencies in both the uninhibited solutions and inhibited ones by lower inhibitor concentrations, the Warburg impedance appeared. In the copper corrosion in oxygenated sulphuric acid solutions at Ecorr the anodic reaction is copper dissolution and cathodic reaction is oxygen reduction being the hydrogen discharge current density negligible as compared to oxygen reduction current density. Then the Warburg impedance could be attributed to oxygen transport from the bulk solution to the copper surface [3]. The adsorption behaviour of gramine followed Temkin’s isotherm. The values of the standard free energy of adsorption of the gramine at 25 °C, 35 °C, 45 °C and 55°C were calculed. A structural model of the interface copper/0.5 M H2SO4 was proposed. [1] O.E. Barcia and O.R. Mattos, Electrochim. Acta 35, 1990, 1601. [2] H. Ashassi-Sorkhabi, N. Ghalebsaz-Jeddi, F. Hasemzadeh and H. Jahani, Electrochim. Acta 51, 2006, 3848. [3] H. Ma, S. Chen, B. Yin, S. Zhao, X. Liu, Corros. Sci., 45, 2003, 867