Henri Patin

Stabilized rhodium(0) nanoparticles: a reusable hydrogenation catalyst for arene derivatives in a biphasic water-liquid system.

A colloidal system based on an aqueous suspension of rhodium(o) nanoparticles proved to be an efficient catalyst for the hydrogenation of arene derivatives under biphasic conditions. The rhodium nanoparticles (2-2.5 nm) were synthesized by the reduction of RhCl3 x 3H2O with sodium borohydride and were stabilized by highly water-soluble N-alkyl-N-(2-hydroxyethyl)ammonium salts (HEA-Cn). These surfactant molecules were characterized by measurements of the surface tension and the aqueous dispersions with rhodium were observed by transmission electron cryomicroscopy. The catalytic system is efficient under ultramild conditions, namely room temperature and 1 atm H2 pressure. The aqueous phase which contains the protected rhodium(0) colloids can be reused without significant loss of activity. The microheterogeneous behavior of this catalytic system was confirmed on a mercury poisoning experiment.

Synergistic relationships in algal-bacterial microcosms for the treatment of aromatic pollutants.

The potential of algal-bacterial microcosms was studied for the biodegradation of salicylate, phenol and phenanthrene. The isolation and characterization of aerobic bacterial strains capable of mineralizing each pollutant were first conducted. Ralstonia basilensis was isolated for salicylate degradation, Acinetobacter haemolyticus for phenol and Pseudomonas migulae and Sphingomonas yanoikuyae for phenanthrene. The green alga Chlorella sorokiniana was then cultivated in the presence of the pollutants at different concentrations, showing increasing inhibitory effects in the following order: salicylate < phenol < phenanthrene. The synergistic relationships in the algal-bacterial microcosms were clearly demonstrated, since for the three contaminants tested, a substantial removal (>85%) was recorded only in the systems inoculated with both algae and bacteria and incubated under continuous lighting. This study presents, to our knowledge, the first reported case of photosynthesis-enhanced biodegradation of toxic aromatic pollutants by algal-bacterial microcosms in a one-stage treatment.

Catalytic hydrogenation of olefins in biphasic water-liquid system

Abstract Cyclic and linear olefins and polyenes with or without functional groups are hydrogenated under very mild reaction conditions. Emphasis is put on the advantages of this method which requires no solvent and a water-soluble non air-sensitive catalyst.

Influence of the initial composition of algal-bacterial microcosms on the degradation of salicylate in a fed-batch culture

The influence of the initial composition of an algal-bacterial microcosm constituted of Chlorella sorokiniana and Ralstonia basilensis was tested for the fed-batch degradation of salicylate at 5xa0mM. Salicylate degradation was always limited by the O2 generation rate, which was initially proportional to the algal density, but rapidly became limited by the availability of light once the algae started to grow. The decrease of the salicylate removal rate observed at high algal densities was likely caused by mutual shading within the algal population and the increase of O2 consumption due to algal dark respiration. With repeated salicylate amendments, all systems converged towards the same characteristics, reaching an optimum rate of salicylate degradation at 1xa0mmolxa0l−1 day.

Aqueous Rhodium Colloidal Suspension in Reduction of Arene Derivatives in Biphasic System: a Significant Physico-chemical Role of Surfactant Concentration on Catalytic Activity

The hydrogenation of benzene derivatives represents an important industrial catalytic transformation. An original approach is to use transition metal nanoparticles that are finely dispersed in liquid media. During the last decade, these nanoparticles have been largely characterized by sophisticated techniques. Recently, we have described the hydrogenation of arene derivatives in liquid-liquid systems catalyzed by an aqueous suspension of rhodium nanoparticles stabilized by a cationic surfactant. Here, we demonstrate that the modulation of surfactant concentration fundamentally influences the turnover frequencies (TOFs) in hydrogenation of classical benzene derivatives such as anisole, toluene and p-xylene. A maximum TOF is obtained when the surfactant concentration is about the critical micellar concentration. In this condition, the Rh(0) stabilized nanoparticles are up to 5-fold more active.

Nucleophilic addition of water-soluble phosphines on activated olefins

Summary Triphenylphosphinc m-trisulfonate P(PhSO3Na)3 = TPPTS and triphenylphosphine m-monosulfonate Ph2PPhSO3Na = TPPMS react in water with α, β unsaturatcd acids affording hydrosoluble phosphonium salts. The conversion is quantitative because water readily protonates the carbanionic intermediate thus displacing the equilibrium towards the right. This nucleophilic addition of hydrosoluble phosphines has been extended to non water miscible activated olefins in biphasic media ; depending on the pH, phosphine oxides or phosphonium salts are obtained. When the reactions are carried out in D2O, the addition products are specifically deuterated.

Organic chemistry in water (part v) Nucleophilic addition of water-soluble phosphines on activated Alkynes : an efficient synthesis of new vinylphosphonium salts and of specifically deuterated olefins

Abstract Triphenylphosphinc m-trisulfonate [P(mC 6 H 4 S0 3 Na) 3 =TPPTS]1 and triphenylphosphine m-monosulfonate [Ph 2 P(mC 6 H 4 SO 3 Na)=TPPMS]2 react in water with activated alkynes R-C s C-A (A = CO 2 H, CO 2 R l , COR 2 , CHO) affording new vinylphosphonium salts or vinylphosphine oxides or alkenes depending on the pH of the aqueous solution and on the nature of the substituent R. The reactions of 1 or 2 with alkynes bearing an electron-acceptor substituent R give rise to the corresponding trans disubstituted olefins. Specifically mono or dideuterated alkenes are thus obtained in good yields by sequential use of H 2 O-D 2 O. When R = H or Alkyl, vinylphosphonium salts or vinylphosphine oxides are quantitatively produced respectively in acidic or in neutral medium

Unprecedented efficient hydrogenation of arenes in biphasic liquid–liquid catalysis by re-usable aqueous colloidal suspensions of rhodium

A reduced aqueous colloidal suspension of rhodium shows efficient activity for the catalytic hydrogenation of various benzene derivatives under biphasic conditions at room temperature and under atmospheric hydrogen pressure; the aqueous phase containing the Rh(0) particles can be re-used for further runs with a complete conservation of activity.

Ruthenium colloids: A new catalyst for alkane oxidation by tBHP in a biphasic water-organic phase system

Abstract Efficient and highly selective conversion of cyclooctane into cyclooctanone is obtained under pure biphasic conditions through t-butylhydroperoxide activation by the in situ formation of colloidal ruthenium species arising from RuCl 3 , 3H 2 O. Model extension experiments to other cycloalkanes are also discussed.

NMR Stereochemical analysis of chiral alkylsulfoxides with α-methoxyaryl acetic acids

Abstract (S)-α-methoxyphenyl and (S)-α-methoxy-2-naphtyl acetic acids (MPA and 2-NMA) were used as NMR chiral shift reagents for the stereochemtical analysis of alkylsulfoxides. It was shown that the use of C 6 D 6 as NMR solvent increased the magnitude of the observed effects for both 1 H- and 13 C-NMR spectra. Moreover, 2-NMA led to a much longer range effect on the chain but lowered the signal spliting of the α-methylene groups.