Metal-free hydrogenation strategy

Frustrated Lewis Pairs A Metal-Free Strategy for Hydrogenation Catalysis... 

I 77 Frustrated Lewis Pairs A Metal-Free Strategy for Hydrogenation Catalysis Table 11.1 Catalytic hydrogenation of imines with phosphonium borate catalysts [45]. 

A common alternative is to synthesize approximate state functions by linear combination of algebraic forms that resemble hydrogenic wave functions. Another strategy is to solve one-particle problems on assuming model potentials parametrically related to molecular size. This approach, known as free-electron simulation, is widely used in solid-state and semiconductor physics. It is the quantum-mechanical extension of the classic (1900) Drude model that pictures a metal as a regular array of cations, immersed in a sea of electrons. Another way to deal with problems of chemical interaction is to describe them as quantum effects, presumably too subtle for the ininitiated to ponder. Two prime examples are, the so-called dispersion interaction that explains van der Waals attraction, and Born repulsion, assumed to occur in ionic crystals. Most chemists are in fact sufficiently intimidated by such claims to consider the problem solved, although not understood. 

The toxic metals present in industrial effluent streams include heavy metals such as silver, lead, mercury, nickel, zinc, and chromium. These heavy metals accumulate in soil and are eventually transferred to the human food chain. In irradiation treatment the general strategy is the reduction of higher oxidation state ions to lower oxidation state ions in lower oxidation state the solubility is usually lower, so often the reduced ions can be separated by precipitation. The reduction is done by the hydrated electron and hydrogen atom (under oxygen-free conditions) and/or by other reducing-type radicals formed in hydroxyl radical + alcohol or in hydroxyl radical + acetic acid reaction (see for instance reaction (O 23.34) and (O 23.144)) (Haji-Saeid 2007 Chaychian et al. 1998 Belloni and Mostafavi 2004 Belloni and Remita 2008). 

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