Chloromethane chemical industry

The Direct Process is the reaction of silicon with chloromethane to form methylchlorosilanes (Eq.l). This reaction is unique, in that it is the only solid-catalyzed gas-solid reaction applied in the chemical industry. The Direct Process was first discovered by Rochow [1] and independently Muller [2] around 1940. 

Chloromethanes have varied applications in the chemical industry. Methyl chloride is mainly used in the manufacture of silicones, tetramethyl lead, and as a solvent. Methylene chloride (often called methylene dichloride or di-chloromethane, DCM) is a multipurpose solvent, a degreasing agent, and a... 

Tetraethyl lead and chloromethane had proved hazardous soon after they entered the consumer market, and both times the chemical industry s initial reaction was to study and stall. Efforts to have the products taken off the market were rebuffed, and the same team was called in for both studies. Events then took very different courses. Study of tetraethyl lead became an excuse for decades of inaction. Study of refrigerants led quickly to substitution of the much safer CFCs for chloromethane. Four decades later, these compounds would be found to endanger the ozone layer of the stratosphere, but Midgley... 

Methanol is a common feedstock considered as a building block in the chemical industry because of its versatility in the synthesis of several important chemicals such as chloromethane, acetic acid, methyl ferf-butyl ether (MTBE), alkyl halides, and formaldehyde [202, 203]. Methanol can be converted into DME which is... 

Chlorination of various hydrocarbon feedstocks produces many usehil chlorinated solvents, intermediates, and chemical products. The chlorinated derivatives provide a primary method of upgrading the value of industrial chlorine. The principal chlorinated hydrocarbons produced industrially include chloromethane (methyl chloride), dichloromethane (methylene chloride), trichloromethane (chloroform), tetrachloromethane (carbon tetrachloride), chloroethene (vinyl chloride monomer, VCM), 1,1-dichloroethene (vinylidene chloride), 1,1,2-trichloroethene (trichloroethylene), 1,1,2,2-tetrachloroethene (perchloroethylene), mono- and dichloroben2enes, 1,1,1-trichloroethane (methyl chloroform), 1,1,2-trichloroethane, and 1,2-dichloroethane (ethylene dichloride [540-59-0], EDC). 

Chloromethane is an important industrial chemical. Olah et al. [56] have reported the selective catalytic monochlorination of methane to chloromethane over superacidic sulfated zirconia solid catalysts, for example 804 /Zr02, Pt/ S04 7Zr02, and Fe/Mn/S04 7Zr02- The reactions were conducted in a continuous-flow reactor under atmospheric pressure. At 200 °C with 30 % chlorine the selectivity to chloromethane was > 90 %.The selectivity could be enhanced by adding platinum. The only by-product was CH2CI2. The latter is formed by the subsequent chlorination of chloromethane. No chloroform or carbon tetrachloride was formed. The authors postulated that chlorination occurs by an electrophilic insertion of an electron-deficient, metal coordinated, chlorine molecule into the C-H bond of methane. One drawback of the process was that above 225 °C, part of the metal was removed as the metal chloride [56]. Formation and subsequent loss of volatile metal chlorides is a major pitfall that should be avoided during vapor-phase chlorination over solid catalysts. 

The US pulp and paper industry operates over 550 facilities which employ over 200,000 people. Total shipments are 60 billion with an additional 80 billion in converted products. Several proeesses eontribute to the emission of solvents. These include chemical pulping kraft process (terpenes, alcohols, methanol, acetone, chloroform), bleaching (acetone, dichloromethane, chloroform, methyl ethyl ketone, carbon disulfide, chloromethane, and trichloroethane), wastewater treatment (terpenes, alcohols, methanol, acetone, chloroform and methyl ethyl ketone), and evaporators in chemical recovery systems (alcohols and terpenes). 

The decreased chemical reactivity resulting from this resonance energy has great practical importance. The chloromethanes, such as carbon tetrachloride, are toxic, because of the ease with which they hydrolyze. The fluorochloromethanes do not hydrolyze in this way, and can be used safely in the home and in industrial plants. There was rapid development of the home refrigerator industry after the discovery of these substances, especially the freons CCI3F (b.p. 23.8°C) and CCI2F2 (b.p. —30°C). They are used also as the vehicle for aerosols. 

Halomethanes have numerous industrial applications (Table 3.2). One of the most important of the group, chloroform, is used mainly as a solvent and an intermediate in the production of various products. Chloromethane and tribromomethane are also employed as chemical intermediates, whereas dichloromethrae is widely used as a solvent. Tribromomethane is a common fumigant, and fluoro-derivatives find general application as refrigerants and aerosol propellants. Recent restrictions placed on the use of fluorocarbons have resulted in a decrease in US production of fluoro-derivatives. During the last decade, production of trichlorofluoromethane declined from 1.3 to 0.7 X 10 tons while dichlorofluoromethane fell from 2.0 to 1.5 X 10 tons (Table 3.1). Production of other halomethanes has shown a consistent albeit small increase in recent years (Table 3.1). Total dichloromethane production now exceeds 2.5 X 10 tons compared with 1.5 and 1.8X itf tons for chloromethane and chloroform, respectively. It is estimated that bromo-methane production will be only about 2.0 X 10 tons in 1982. 

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