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PK Lim


One objective of our current research is to develop oil-water interfacial synthesis as a benign alternative to conventional syntheses that require the use of toxic solvents. In the interfacial synthesis, a combination of innocuous oil and aqueous phases is used in place of toxic organic solvents. The multiple functions which previously limited the choice of a solvent are now decoupled and are met separately by a biphasic mixture. The desired reaction is effected at the oil-water interface by means of a surface-active catalyst complex, the use of an emulsifier, and optimization of oil-water phase ratio and pH of the aqueous phase.

A novel biphasic synthesis technology is being developed for commercial application as a result of pioneering work performed in our laboratory. The technology utilizes a biphasic liquid mixture ­ typically an aqueous­organic mixture ­ as the reaction medium, a surface­active catalyst complex to effect the desired synthesis reaction at the interface, and an emulsifier to increase the interfacial area. Major advantages of the new technology include:

  1. Circumvention of the solubility incompatibility problem between reactants or between a reactant and the catalyst
  2. Avoidance of the use of a toxic or hazardous organic solvent that may otherwise be needed;
  3. Easy catalyst recovery and re-use while retaining the characteristic advantages of homogeneous catalysis, namely, high reactivity, selectivity and reproducibility under mild reaction conditions;
  4. Possibility of simultaneous product removal during reaction such that the yield of desired intermediate product may be increased; and
  5. Possibility of regio- and stereoselectivity control through the directional influence of the liquid-liquid interface on molecular orientations.

A wide selection of tasks is available in this emerging field, including development of a novel column reactor that permits simultaneous reaction and product removal, application of the technology to specific synthesis reactions of commercial interest, development of surface-active ligands with the desired metal-complexing ability and catalyst promoting effect, and fundamental kinetic and modelling studies.

Research Description

Focus Areas - Interfacial Phenomena. Homogeneous Catalysis. Free Radical Chemistry.