Transition Metal-Catalyzed Polymerization in Aqueous Systems

I 7 Transition Metal-Catalyzed Polymerization in Aqueous Systems... 

The previous section demonstrated the utility of polymerization reactions in aqueous systems. Carrying out transition metal-catalyzed polymerizations in aqueous systems is of great interest as they can afford a variety of new materials not accessible by established free radical techniques. Thus, various monomers subject to catalytic polymerization can not be polymerized by free radical polymerization, and catalytic polymerization also offers access to other polymer microstructures. 

Although the possibility of carrying out catalytic polymerizations in the presence of water had been known since the 1960s, significant advances in catalytic polymerizations in aqueous systems have only been achieved over the past decade. Today, (1) various different types of transition metal-catalyzed polymerizations can be carried out efficiently in aqueous systems. (2) A variety of polymers, ranging from hydrocarbons to water-soluble polymers, and a scope of polymer architectures are accessible. (3) Polymerization can be carried out in a controlled fashion. 

In addition to the reactions discussed above, there are still other alkyne reactions carried out in aqueous media. Examples include the Pseudomonas cepacia lipase-catalyzed hydrolysis of propargylic acetate in an acetone-water solvent system,137 the ruthenium-catalyzed cycloisomerization-oxidation of propargyl alcohols in DMF-water,138 an intramolecular allylindination of terminal alkyne in THF-water,139 and alkyne polymerization catalyzed by late-transition metals.140... 

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