Diamonds halogen compounds

In principle, oxidation could occur simultaneously during a HDH (reduction) reaction. For example any de-halogenated compounds could be oxidised to C02 in the anode compartment. Thus in the case of pentachlorophenol the phenol produced by the HDH could be oxidised at a suitable anode (e.g. boron-doped diamond) to C02 ... 

Patents describe the synthesis of diamonds by contacting diamond powder as crystal seeds at about 700 to 1400 K with Pb(C2H5)4 at a partial pressure of 10 to 10" bar [872, 877, 881]. Reaction of Pb(C2H5)4 with halogen, e.g., fluorine or halogen compounds. Is claimed to give lead halide glass preforms for low-loss optical fibers [904]. 

As an element, silicon is a hard brittle metallic-looking substance which crystallizes in the diamond lattice. It is produced commercially by the electrothermal reduction of silica, resulting in a product which contains about 97 per cent silicon. The element shows no visible oxidation or corrosion at ordinary temperatures and oxidizes very slowly below red heat. Halogens attack it more readily, and chlorination proceeds satisfactorily at 250° C. to form the silicon chlorides which are perhaps the best-known volatile compounds of silicon. Whenever the element is exposed to nascent hydrogen, or its metallic compounds are treated with acids, some hydrides usually are formed, as may be noticed by the odor which such hydrides impart to the gas evolved when cast iron is dissolved in dilute acids. A mixture of concentrated nitric and hydrofluoric acids will dissolve pure silicon, but mineral acids singly will not do so. Hot concentrated solutions of alkalies will dissolve it, however, with the evolution of hydrogen. 

The coordination number of carbon with oxygen is three (cf., Table 1), which is also the coordination number found in elemental carbon (graphite). The coordination number of four is found only in compounds in which carbon is bonded to hydrogen or a halogen, or in compounds such as diamond that are formed under pressure. See Sect. 8.1.1 for a fuller discussion of the coordination number of hydrogen. 

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