Halogenated hydrocarbons methyl iodide

The halogen compounds used were methylene dichloride, chloroform, carbon tetrachloride, ethylene dichloride, ethyl bromide, ethylene dibromide, bromoform, methyl iodide, and ethyl iodide. The hydrocarbons selected for their interesting combustion properties were hexane, 2-methylpentane, 2,2-dimethylbutane, hex-l-ene, heptane, methylcyclo-hexane, isooctane, diisobutylene, benzene, toluene, m-xylene, and ethylbenzene. 

Synthesis.—We have shown that the alkyl halides are mono-substitution products of the hydrocarbons, i.e., one hydrogen of the hydrocarbon has been substituted by a halogen, e.g., methyl iodide, CH3—I. Now when methyl iodide is treated with ammonia a new compound is formed having the composition CHsN and the other product of the reaction is hydrogen iodide. 

Wurtz reaction. A method of synthesizing hydrocarbons discovered by Wurtz in 1855. It consists in treatment of an alkyl halide with metallic sodium, which has a strong affinity for bound halogen and acts on methyl iodide in such a way as to strip iodine from the molecule and produce sodium iodide. The reaction involves two molecules of methyl iodide and two atoms of sodium. 

Two mononitroxylenes can be derived, theoretically, from orthoxylene, three from metaxylene, and but one from paraxylene. It follows, therefore, that the xylene boiling at 142°, from which two mononitro derivatives can be prepared, is orthoxylene, and that the ones boiling at 139° and 138° have the meta and para structure, respectively. The application of the so-called absolute method leads to the establishment of the structure of the three xylenes, which can serve, therefore, as reference-compounds. The three hydrocarbons yield three dibasic acids on oxidation orthoxylene gives phthalic acid, metaxylene gives isophthalic acid, and paraxylene gives terephthalic acid. The three phthalic acids become, thus, reference-compounds. Other compounds can be readily converted into xylenes or phthalic acids, and can, therefore, be used in the determination of structure. Thus, the three dibromobenzenes can be converted into the three xylenes by Fittig s synthesis. The transformations establish the structure of the halogen derivatives. From these other compounds may be prepared. An example will be instructive. The dibromobenzene which melts at 89° is converted into paraxylene when treated with methyl iodide and sodium —... 

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