Water-organic Biphasic System Research Articles

Water-Soluble Noble Metal Nanoparticle Catalysts Capped with Small Organic Molecules for Organic Transformations in Water.

This article recaps a variety of interesting catalytic studies based on solubilized and freely movable noble metal nanoparticle catalysts employed for organic reactions in either pure water or water-organic biphasic systems. Small organic ligand-capped metal nanoparticles are fundamentally attractive materials due to their enormous potential as a well-defined system that can provide spatial control near active catalytic sites. The nanoparticle catalysts are first grouped based on the synthetic method (direct reduction, phase transfer, and redispersion) and then again based on the type of reaction such as alkene hydrogenation, arene hydrogenation, nitroaromatic reduction, carbon-carbon coupling reactions, etc. The impacts of various ligands on the catalytic activity and selectivity of semi-heterogeneous nanoparticles in water are discussed in detail. The catalytic systems using polymers, dendrimers, and ionic liquids as supporting or protecting materials are excluded from the subject of this review.

Catalytic dehydration ofd-xylose to furfural over a tantalum-based catalyst in batch and continuous process

The conversion ofd-xylose to furfural was developed through a batch and continuous process in water–organic biphasic system using TA-p as a catalyst.

Partition coefficients of macrocyclic crown ethers in water–organic biphasic system: DFT/COSMO-RS approach

The partition coefficients for a large number of macrocyclic crown ethers in different water–organic bi-phasic systems at BP-SVP-AM1 and BP-TZVP level of theory using novel conductor like screening model for real solvents (COSMO-RS) approach are presented here for the first time. The predicted values of partition coefficient obtained from the present calculation are compared with the available reported experimental results. The calculated values of partition coefficient obtained from the first principle based COSMO-RS theory are in reasonably good agreement with the available experimental results. The present study reveals that the solvents with strong hydrogen bond donating, weak hydrogen bond accepting and high dipolarity/polarizability are the good solvents for partitioning of a neutral organic solute. The partitioning of a neutral solute in a particular solvent is enhanced due to increased hydrophobicity.

Nickel(0)-TPPTS-Cyanide Complex in Water. An Efficient and Flexible Catalyst for the Isomerisation of Olefinic Compounds at Room Temperature

For the past 30 years, the TPPTS synthesis has allowed the development of water-organic biphasic systems offering new green processes with an easy catalyst separation. However, olefin isomerisation reactions based on nickel phosphite or phosphine complexes in organic media cannot be easily adapted in a water-organic biphasic system because the Ni(0)-TPPTS complex is not stable enough in an aqueous medium. To make this adaptation successful, we stabilized the Ni(0)-TPPTS complex with cyanide ligands in basic medium. Such a biphasic Ni(0)- TPPTS-cyanide system revealed a high catalytic activity for the isomerisation of butenes and other olefins at room temperature with a simple catalyst separation.

Novel pyridinium based cobalt carbonyl ionic liquids: synthesis, full characterization, crystal structure and application in catalysis

Through an optimized synthetic strategy, a series of novel alkylpyridinium cobalt tetracarbonyl salts, [C(1)Py][Co(CO)(4)] (), [C(4)Py][Co(CO)(4)] () and [C(16)Py][Co(CO)(4)] () (C(n)Py = N-C(n)H(2n+1)-pyridinium), were successfully prepared in good yields, using a water-organic biphasic system. All the three compounds melt well below 100 degrees C and could be classified as ionic liquids. The compounds were fully characterized using IR, UV-Vis, (1)H NMR, (13)C NMR, ESI-MS and elemental analysis, and was structurally characterized by X-ray single crystal analysis. Compound has been found to be an efficient and reusable catalyst for the alkoxycarbonylation of propylene oxide without the aid of a base additive.

Hydrolysis of olive oil by pancreatic lipase in biphasic organic-aqueous system

Six ethylene oxide-based surfactants were tested for their suitability to mediate lipase action on olive oil in a water-organic biphasic system. In Slovasol EL only it was possible by lipase to catalyze hydrolysis of the substrate over a wide range of isooctane and water content in the system. The Michaelis-Menten parameters of lipase measured for this system are comparable with those measured in a reversed emulsion of water and oil-isooctane solution. The hydrolysis rate was not increased, however, in the presence of isooctane.