Electric discharge halides

A brief summary of some electric discharge halide syntheses is given in Table II. 

Nitrogen and sodium do not react at any temperature under ordinary circumstances, but are reported to form the nitride or azide under the influence of an electric discharge (14,35). Sodium siHcide, NaSi, has been synthesized from the elements (36,37). When heated together, sodium and phosphoms form sodium phosphide, but in the presence of air with ignition sodium phosphate is formed. Sulfur, selenium, and tellurium form the sulfide, selenide, and teUuride, respectively. In vapor phase, sodium forms haHdes with all halogens (14). At room temperature, chlorine and bromine react rapidly with thin films of sodium (38), whereas fluorine and sodium ignite. Molten sodium ignites in chlorine and bums to sodium chloride (see Sodium COMPOUNDS, SODIUM HALIDES). 

Reductive methods form B—B bonds from B—X bonds. For B2X4 (X = Cl, Br, I) from BXj, an electric discharge is supplemented by the presence of a metal, or metal atoms, as halide scavenger. The passage of BX3 at low pressure through a rf discharge in the presence of Hg produces the diboron tetrahalides B2X4 at 300 mg h ... 

Fibers of titanium diboride can be prepared by reaction (a) at 400°C in an electrical discharge. Adherent layers of certain metal borides on metal substrate surfaces are obtained by thermal decomposition of metal (Mo, W, Nb, Ta) halides and BBr3 on a metallic substrate using a solar furnace or induction heating ... 

It can also be prepared from carbon and nitrogen by electric discharge between carbon electrodes in a nitrogen atmosphere. Numerous derivatives of cyanogens are known, including cyanogen halides, XCN. These compounds form trimers known as the cyanuric halides, which have the cyclic structure... 

Elastic-inelastic collision model, Szilard-Chalmers reaction and, 1 269 Electrical conduction, in organic superconductors, 29 278-286 Electrical conductivity of chalcogenide halide compounds, 23 331 of Group IB, 23 337-339, 342, 346-349 photoelectric effects, 23 368, 410 semiconductors, 23 368, 390, 395-396, 400-402, 410-412 superconductors, 23 375-377 of graphite intercalation compounds, 23 290, 294, 309-310, 312, 317-318 Electric discharges arc type, 6 146-147 chemical reactions in, 6 189-191 chemical reactions in, 6 143-206... 

The first moderate-yield process for the formation of B—H bonds from the reaction of Hj with boron halides utilizes passage of mixtures of and BClj through an electrical discharge between Cu electrodes. When H BClj is 10 at 2.67 X 10 Pa, yields of < 60% B H, based on BClj consumed in 2 h, are available. This approach is more convenient when BBrj is used instead of BClj. The lower volatility of the bro-mo species makes the process simpler and separation of products more convenient. This discharge process proceeds in steps ... 

The simplest hydrides and halides of boron, silicon, germanium, phosphorus, and arsenic can be decomposed in electric discharges to form... 

Halides. The author is aware of only one example of the preparation of a ternary halide in an electric discharge. Massey and Urch (36) obtained a very small sample of impure SiCl3BCl2 as a by-product from the mercury discharge synthesis of B0CI4. The silicon probably originated from the quartz discharge cell used. It appears that the essentially unexplored study of mixtures of halides in electric discharges is worthy of study. 

New Hazardous Waste Regulations were introduced in July 2005 and under these regulations electric discharge lamps and tubes such as fluorescent, sodium, metal halide and mercury vapour are classified as hazardous waste. While each lamp only contains a very small amount of mercury, vast numbers are used and disposed of each year, resulting in a significant environmental threat. The environmentally responsible way to dispose of lamps and tubes is to recycle them and this process is now available through electrical wholesalers, as described in Chapter 1. 

In arc lamps, the emission is obtained by the activation of a gas by collision with accelerated electrons generated by an electric discharge between two electrodes, typically tungsten-made. The type of lamp is often denoted by the gas contained in the bulb including neon, argon, xenon, krypton, sodium, metal halide and mercury. In particular, for mercury lamps, the following classification, based on the Hg pressure, is done ... 

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