Aqueous transition-metal catalysis

However, in the first place the application of water in catalysis pursues several, although less ambitious, but rather practical, goals. 

Water may be a reagent, being the cheapest source of either oxygen for the formation of oxygen-containing products (alcohols, acids, ketones, aldehydes, etc.), or hydrogen, as in some reduction processes. 

Water is an amphoteric compound, and thus it can lend all types of assistance, whichever is required in a given process, or even a combination of several. It may itself be a general acid or base catalyst, or, in the presence of other acids and bases, serve as an environment deploying proton or hydroxide ion for specific acid or base catalysis. 

Water and aqueous solutions are preferred media for reactions involving 

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I.P. Beletskaya and C.V. Cheprakov, Aqueous transition-metal catalysis, in organic synthesis in water, Paul A. Grieco, ed., Blackie Academic and Professional, 1998, pp. 196-205. 

The reactivity of the double bond in this molecule toward water would, however, interfere with its application as a ligand for aqueous transition-metal catalysis [19]. 

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