Methyl chloride, combustion

Reinhardt, T., and D. E. Ward, Factors Affecting Methyl Chloride Emissions from Forest Biomass Combustion, Enriron. Sci. Techno , 29, 825-832 (1995). 

CH3C1 (g). Thomsen15 and Berthelot70 measured the heat of combustion of methyl chloride. Thomsen s15 data yield Q/=20.1. 

Calculate the standard heats of formation of benzene)/), methanol(Z), aniline(/), methyl chloride)/ ), and ethyl mercaptan(Z) using heat-of-combustion data, knowledge of the combustion products, and the equations in Table 1.20. 

The generally accepted 529 value of the heat of formation of carbon tetrachloride is due to Bodenstein et who measured the heat of the reaction GGI4 4- 2H2 G + 4HC1. They obtained A//y(CCl4 g) = 25 5 kcal, but in view of the slight uncertainty about the heat of formation of the form of carbon produced, the figure after the decimal point is probably not justified. From this (C C1) =70 0 kcal. The heat of formation of methyl chloride is due to a combustion by Thomsen 523 20 kcal. From... 

Reinhardt T. E. and Ward D. E. (1996) Eactors affecting methyl chloride emissions from forest biomass combustion. Environ. Sci. Technol. 29, 825—833. 

Fletcher and Pilcher ( ) derived the enthalpy of formation by measuring the enthalpy of combustion of methyl chloride by flame calorimetry. They reported a value A H (CHgCl, g, 298.15 K) -19.59 0.16 kcal mol" where the error, according to the authors, is twice the standard deviation of the mean including the uncertainty in calibration, measurement, determination of ignition energy, and values of auxiliary data used. 

The temperature at which gas phase reactions must be taken into account will depend on the nature of the fuel and the fuel air ratio. A recent simulation of the catalytic combustion of methyl chloride using a model that included a detailed gas phase reaction mechanism found that the gas phase reactions start to make a significant contribution to the overall reaction rate at wall temperatures above 700 °C [10], In the case of methane, the primary constituent of natural gas, there is evidence that gas phase reactions start to play a role at wall temperatures above 1000 °C [11]. 

Among various natural sources, the largest amounts of chlorinated hydrocarbons are supplied into the air by forest fires. In the combustion of cellulose, 2.2 mg of methyl chloride are formed per 1 g of substance burnt. Anthropogenic sources include the combustion of PVC (polyvinyl chloride) wastes, burning of plants in agriculture and uncontrolled fires resulting from human activity. 

Atmospheric halogen compounds (Penkett, 1982) are of both natural and industrial origin. Probably the most abundant halocarbon in the troposphere is methyl chloride, CH3CI, which is present at a level of 0.6-2 parts in 10 . It appears to be present in volcanic emissions, formed by microbial fermentation, by the combustion of vegetation (Lovelock, 1975), and by the SN2 reaction of methyl iodide (a constituent of marine algae) with the large excess of chloride ion in seawater (Zafiriou,... 

In the new process [112], [113] methylation is carried out with a phase transformation catalyst based on a quaternary ammonium or phosphonium compound (Fig. 34) in the present of a linear polyether in a two-phase mkture. Methanol is no longer used as the reaction medium and so energy-intensive distillation ceases to be necessary. Toxic dimethyl sulfate is replaced by methyl chloride as the methylating agent. The catalyst is recycled. Only spent catalyst with filtration residue are combusted as waste. 

Circumstances may make it impossible to attack the valve, and in such a case, the flame may be allowed to continue burning while the surrounding area and objects are cooled with water spray. Provide employees engaged in extinguishing fires with gas masks to protect them from methyl chloride vapors and the toxic combustion products formed. 

Hung S, Barresi A, Pfefferle L. Flow Tube Reactor Studies of Catalytically Stabilized Combustion of Methyl Chloride. Proceedings of the 23 International Symposium on Combustion. Orleans, France Combustion Institute 1991. p. 909-915. 

To set an example, we will calculate the value of the different measures related to a branching chain reaction during hydrogen combustion. To do so, we will consider a simplified diagram inspired by James et al. for the inhibition of hydrogen combustion by methyl-chloride (reaction steps [12.R21] to [12.R27]) ... 

Combustion in incinerators, or by open burning, may lead to the production of low molecular weight oligomers, or of chlorinated C1-C2 materials such as methyl chloride. Methyl chloride has been postulated as a major product of the combustion of agricultural waste, and of slash and burn land clearance [42] estimates suggest that as much as 5 x 10 tonnes per year of methyl chloride could be emitted from all fires throughout the world. There have been suggestions that both chloroform and carbon tetrachloride may have a natural atmospheric source, by chlorination of methane [34] but there is no confirmation, despite their ubiquitous presence, and the known occurrence of free chlorine. 

When HPLC is used as part of the analysis, the mobile phase is typically a mixture of methanol and methyl-tert-butyl ether (i.e., 50 50, v/v), although other HPLC solvents for LC/MS using APCI (e.g., water, tetrahydrofuran) can be used. It is important to note that if combustible nonaqueous solvent systems are used, water or a halogenated solvent such as methylene chloride or chloroform should be added to the mobile phase postcolumn to suppress ignition in the ion source. In addition, the APCI source must be vented outside the laboratory and should not allow air into the ionization chamber. A scan range of m/z 300 to 1000 will include the known carotenoids and their most common esters. 

If RX is methyl iodide, bromide, or chloride, it may cool the flame and, consequently, reduce combustion. Further, the phosphine can be oxidized readily to the phosphine oxide. The latter reaction may lead to self-extinguishing properties either by absorption of energy to complete the reaction and/or more likely by formation of the polyphosphates and the subsequent shielding of the polymer by this thermally stable glass (19). 

The strain energy of the cyclopropane ring is determined from thermochemical measurements on two closely related compounds the /r-butyl ester of cyclopropanecarboxylic acid and the methyl ester of cyclohexanecarboxylic acid. Both compounds can be synthesized from the appropriate acid chlorides, and their heats of combustion measured with a bomb calorimeter. 

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