Methyl chloride, sources

Methyl Chloride. Most of the HCl consumed in the manufacture of methyl chloride [74-87-3] from methanol (qv) is a recycled product. The further reaction of methyl chloride with chlorine to produce higher chlorinated methanes generates significant amounts of HCl which are fed back into methyl chloride production. Another source of recycled HCl is siUcone production based on methyl chloride. 

Thermal chlorination of methane was first put on an industrial scale by Hoechst in Germany in 1923. At that time, high pressure methanol synthesis from hydrogen and carbon monoxide provided a new source of methanol for production of methyl chloride by reaction with hydrogen chloride. Prior to 1914 attempts were made to estabHsh an industrial process for methanol by hydrolysis of methyl chloride obtained by chlorinating methane. 

The synthesis and purification of cumyl alcohol (CumOH), p-dicumyl methyl ether (DCE)) and 2-chloro-2,4,4-trimethylpentane (TMPC1), and the sources and purification of methyl chloride (MeCl), methylcyclohexane (MCHx), isobutylene have been described [9, 10]. P-Pinene (P-PIN), (Aldrich), was chromatographed over alumina (activity I, Fisher), and freshly distilled over CaH2 under nitrogen according to 1H-NMR spectroscopy and GC analysis the purity was >99%. 2,6-Di-/er/-butylpyridine (DtBP), (Aldrich), anhydrous A,A-dimethylacetamid (DMA), (Aldrich), ethylaluminum dichloride (EtAlCl2), 1.0 M solution in hexanes (Aldrich), and methanol (Fisher) were used as received. 

Thousands of tonnes of methyl chloride are produced naturally every day, primarily in the oceans. Other significant natural sources include forest and brush fires and volcanoes. Although the atmospheric budget of methyl chloride can be accounted for by volatilization from the oceanic reservoir, its production and use in the manufacture of silicones and other chemicals and as a solvent and propellant can make a significant impact on the local atmospheric concentration of methyl chloride. It has been detected at low levels in drinking-water, groundwater, surface water, seawater, effluents, sediments, in the atmosphere, in fish samples and in human milk samples (Holbrook, 1993 United States National Library of Medicine, 1998). Tobacco smoke contains methyl chloride (lARC, 1986). 

Methyl iodide is produced by many marine photosynthetic organisms and therefore the ocean is thought to be a major natural source of methyl iodide. Some of this is released to the atmosphere and some reacts with seawater to form methyl chloride. Industrial emissions of methyl iodide may occur in conjunction with its use as a methylating agent and in organic synthesis. Humans are exposed to methyl iodide from the ambient air and from ingesting seafood (United States National Library of Medicine, 1998). 

Cox ML, Sturrock GA, Fraser PJ, Siems ST, Krummel PD, O Doherty S (2003) Regional Sources of Methyl Chloride, Chloroform and Dichloromethane Identified from AGAGE Observations at Cape Grim, Tasmania, 1998-2000. J Atmos Chem 45 79... 

Yokouchi Y, Noijiri Y, Barrie LA, Toom-Sauntry D, Machida T, Inuzuka Y, Akimoto H, Li H-J, Fujinuma Y, Aoki S (2000) A Strong Source of Methyl Chloride to the Atmosphere from Tropical Coastal Land. Nature 403 295... 

Varner RK, Crill PM, Talbot RW (1999) Wetlands A Potentially Significant Source of Atmospheric Methyl Bromide and Methyl Chloride. Geophys Res Lett 26 2433... 

The enthalpy of formation of methyl chloride is from our archival source, while that of acetonitrile is from X.-W. An and M. M nsson, J. Chem. Thermodyn., 15,287 (1983). 

As was pointed out in the discussion of the Grignard method, a larger part of the chlorobenzene molecule appears in the finished silicone product than is true of the methyl chloride molecule. At the same price per pound for raw materials, the basic material cost for phenyl silicone therefore would be less than that for methyl silicone. The difference is accentuated by the fact that chlorobenzene is produced in very large volume at low cost, so that it becomes an inexpensive source of phenyl groups for phenyl silicone. On the other hand, the factors which act to increase the relative cost of phenyl silicone by the direct method are (1) the cost of recovering the silver catalyst, and (2) the possible uneconomical disposition of the hydrochloric acid, which cannot easily be recirculated in the process. 

The formation of the expected 2,4,6-trisilaalkanes 2 can be explained by the 2 1 reaction of (chloromethyl)silanes 1 and elemental silicon. The byproducts, 1,3-disilaalkanes 3, were obtained from the reaction of (chloromethyl)silane reactant 1 and hydrogen chloride (or chlorine) with the same silicon atom, as methyldichlorosilane (or methyltrichlorosilane) was obtained from the methyl chloride reaction. This result indicates that some of the (chloromethyl)silane reactant decomposed under the reaction conditions and acted as a chlorine or hydrogen chloride source. In the direct reaction of (chloromethyl)dimethylchlorosilane (lc), a significant amount of starting material was recovered at temperatures below 300 °C, but the reaction went to completion above 320 °C. 2,6-Dimethyl-2,4,4,6-tetra-chloro-2,4,6-trisilaheptane (2c) was obtained in much higher yields than 3-methyl-l,l,l,3-tetrachloro-l,3-disilabutane (3c) at reaction temperatures ranging from 280 to 320 °C, but the ratio of both compounds reversed above 340 °C. 

Stratospheric source gases - A variety of gases transport chlorine into the stratosphere. These gases are emitted from natural sources and human activities. For chlorine, human activities account for most that reaches the stratosphere. The CFCs are the most abundant of the chlorine-containing gases released in human activities. Methyl chloride is the most important natural source of chlorine ... 

To solve the problem (Fig. 2), variable amounts of liquid methyl chloride are injected as a fine spray, upstream of the compressor, to control the gas temperature. Liquid methyl chloride from a supply source enters the desuperheater at constant pressure, flows down the jacket and enters the main line through exposed, tangentially drilled ports. 

Varner R. K., Grill P. M., and Talbot R. W. (1999) Wetlands a potentially significant source of atmospheric methyl bromide and methyl chloride. Geophys. Res. Lett. 26, 2433-2436. 

Yokouchi Y., Noijiri Y., Barrie L. A., Toom-Sauntry D., Machida T., Inuzuka Y., Akimoto H., Li H.-J., Fujinuma Y., and Aoki S. (2000) A strong source of methyl chloride to the atmosphere from tropical coastal land. Nature 403,... 

The Oceans as a Source of Gases to the Atmosphere 2.1 Dimethyl sulfide Methyl mercaptan Carbonyl sulfide Carbon disulfide Hydrogen sulfide Methyl iodide Methyl chloride Chloroform Nitrous oxide Methane... 

---