Halogenation with iodine vapor

Sodium combines with all halogens forming sodium hahdes. The metal ignites with fluorine, forming hydrogen fluoride. Thin metal film reacts readily with chlorine and bromine at ordinary temperatures. Molten sodium burns in chlorine producing sodium chloride. The metal reacts with iodine, only in vapor phase, forming sodium iodide. 

Violent reactions with ammonium salts, chlorate salts, beryllium fluoride, boron diiodophosphide, carbon tetrachloride + methanol, 1,1,1-trichloroethane, 1,2-dibromoethane, halogens or interhalogens (e.g., fluorine, chlorine, bromine, iodine vapor, chlorine trifluoride, iodine heptafluoride), hydrogen iodide, metal oxides + heat (e.g., beryllium oxide, cadmium oxide, copper oxide, mercury oxide, molybdenum oxide, tin oxide, zinc oxide), nitrogen (when ignited), silicon dioxide powder + heat, polytetrafluoroethylene powder + heat. 

With iodine, a pure polyacetylene film is mounted in a glass vessel to which a bulb containing the halogen is attached. The iodine container is held at a fixed temperature to produce a known vapor pressure of iodine. The halogen content in the final product and, at various stages in the reaction, is determined from weight uptake and by chemical analysis [9]. 

The treatment of unsaturated substances with halogen leads to addition to these molecules. This is true not only of bromine and chlorine vapor but also of the less reactive iodine. Substitution also occurs in the presence of light. Examples of such halogenations are listed in Table 12. Figure 32 illustrates the characterization of fluorescein in a bubble bath preparation. Bromination of the fluorescein in the start zone yields eosin. 

Silicon, like carbon, is relatively inactive at ordinary temperatures. But, when heated, it reacts vigorously with the halogens (fluorine, chlorine, bromine, cmd iodine) to form halides and with certain metals to form silicides. It is unaffected by all acids except hydrofluoric. At red heat, silicon is attacked by water vapor or by oxygen, forming a surface layer of silicon dioxide. When silicon and carbon are combined at electric furnace temperatures of 2,000 to 2,600 °C (3,600 to 4700 °F), they form silicon carbide (Carborundum = SiC), which is an Importeint abrasive. When reacted with hydrogen, silicon forms a series of hydrides, the silanes. Silicon also forms a series of organic silicon compounds called silicones, when reacted with various organic compounds. 

Halogens react with the metal at elevated temperatures. Fluorine reacts with ruthenium at 300°C forming colorless vapors of pentafluoride, RuFs, which at ordinary temperatures converts to a green solid. Chlorine combines with the metal at 450°C to form black trichloride, RuCF, which is insoluble in water. Ru metal at ambient temperature is attacked by chlorine water, bromine water, or alcoholic solution of iodine. 

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