Metals water cleavage

The primary target of studies on photocatalytic semiconductor suspensions has been water cleavage by visible light. Suspension-based photocatalytic processes are also useful for the removal of inorganic (metal ions) and organic pollutants, the reduction of CO2, the photodestruction of bacteria and viruses, and various organic reactions an example is the use of Pt-loaded CdS for the photocatalytic racemization of L-lysine [210]. 

Boronic acid hnkers (Tab. 3.6) are useful for the attachment of diols, the protection of glycosides [105] or as precursors for the metal-mediated cleavage [106]. The boronates formed are sensitive to water and simple hydrolysis is sufficient for cleavage. Recently, Carreaux and Carboni developed a new boronate-based strategy for traceless sohd-phase synthesis of aromatic compounds [107]. 

WATER CLEAVAGE USING SIMPLE METAL SALTS AS CATALYSTS 493... 

WATER CLEAVAGE USING METAL COMPLEXES AS CATALYSTS 495... 

Redox potentials for various different Feu/Fem couples are shown in Table 3 and although [Fe(OH)2] is thermodynamically capable of reducing water to hydrogen and does so at elevated temperatures,39 the rate of the reaction is low. It can, however, be increased by the addition of suitable catalysts, eg. Ni salts,39,40 excess [FeSOJ,40 metals such as Ni,40 Cu,40 Pd,18,41 or colloidal Pt.40 Nevertheless, cyclic water cleavage based on this system is unlikely since [Fe(OH)3] is a. highly stable material. 

Although efforts have been made to achieve photochemical or metal-catalyzed cleavage of water to H2 and 02, none is yet practical. However, hydrogen has been obtained from OH groups4 in the reaction [Cp = l,3-(Me3Si)2QH3], which is an oxidative elimination ... 

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