Halogenated hydrocarbons methyl chloride

With PBAs the compressed gases often used are nitrogen or carbon dioxide. These gases are injected into a plastic melt in the screw barrel under pressure (higher than the melt pressure) and form a cellular structure when the melt is released to atmospheric pressure or low pressure. The volatile liquids are usually aliphatic hydrocarbons, which may be halogenated, and include materials such as carbon dioxide, pentane, hexane, methyl chloride, etc. Polychlorofluoro-carbons were formerly used but they have now been phased out due to environment problems. 

In the field of halogenation, the practical aspects of the work were stressed by a number of Russian workers. Thus, in 1940 and later Mamedaliev reported (215) on the chlorination of methane over cupric chloride, pumice, iron, or aluminum shavings. Yields of 75 to 80% of products ranging from methyl chloride to carbon tetrachloride with small amounts of hexachloroethane were obtained. Similar work on the continuous chlorination of hydrocarbons such as isopentane, unsaturated compounds, oxygenated compounds, and on the mechanism of chlorination has been reported by Russian researchers from time to time (180,248,366,367,389). 

Isotactic Polystyrene. The familiar steam molding of pre-expanded particles has so far not been applied successfully to isotactic polystyrene. However, the polymer has been foamed, according to three disclosed methods. For example, finely divided acetone-insoluble polymer, with a melting point in excess of 200°C., is blended with a liquid selected from methylene chloride, aromatic hydrocarbons, or halogenated aromatic hydrocarbons. This blend is then heated (84). A mixture of molten polymer and methyl chloride, propane, or butane is suddenly depressurized (8). Foam may also be generated in a continuous manner directly from a butyllithium-initiated polymerization conducted in the presence of a 4/1 blend of benzene and petroleum ether (15). 

Halogenation of hydrocarbons. Walling found /-butyl hypochlorite useful for light- or radical-induced chain chlorination of toluene. Thus, in the presence of azobisisobutyronitrile as initiator, the reaction with toluene at 40° affords benzyl chloride (84%), /-butanol (97%), and 1-3% each of chlorololuenes, methyl chloride, and acetone. 

Gustorf and co-workers (264-266) have prepared complexes of the type (7r-CH2=CHX)Fe(CO)4 [X = OCOCH3 (266), Cl, CH3, CeHs, or OCH3 (265)] by irradiation of Fe(CO)5 with the corresponding olefin. The complexes are very oxygen-sensitive and thermally unstable. At room temperature they decompose to yield the olefin and Fe3(CO)i2. The order of thermal stability is vinyl chloride > styrene > propylene > vinyl methyl ether. The vinyl chloride and styrene complexes show catalytic activity for polymerization of methyl methacrylate in the presence of a small amount of halogenated hydrocarbon, e.g., CCI4, at room temperature (265). 

The chlorination of paraffin hydrocarbons has been studied recently with the hope that natural gas and petroleum might prove a source for halogen derivatives of value in the arts. It has been shown, for example, that when a mixture of 5 volumes of methane and 4 volumes chlorine is heated to about 280" and passed over clay covered with aluminium chloride, there can be attained from 1000 cubic feet of the hydrocarbon about 50 pounds of carbon tetrachloride and 190 pounds of chloroform. Since natural gas contains methane and ethane the method may prove of value industrially for the preparation of the chlorine substitution-products of the hydrocarbons. If the chlorination can be controlled to give a high percentage of methyl chloride and if a way can be found to hydrolyze the latter in a satisfactory way to methyl alcohol the reactions will be of technical interest in the preparation of this important alcohol. 

Friedel and Crafts Synthesis,—In the presence of anhydrous aluminium chloride, aliphatic halogen compounds react with aromatic hydrocarbons and form condensation-products as the result of the elimination of halogen hydride. Thus, when a mixture of benzene and aluminium chloride is treated with methyl chloride, toluene is formed —... 

Incompatibilities and Reactivities Strong oxidizers acids, halogenated hydrocarbons [Note Corrodes in contact with acids other metals. Ignition may occur if powders are mixed with halogens, carbon disulfide, or methyl chloride.] ... 

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