For methyl bromide

Ratio of rate constant k for indicated alkyl bromide to k for methyl bromide at 25 C... 

The primary use for methyl bromide is in the extermination of insect and rodent pests. Methyl bromide is used in space and stmctural fumigation except in California. The material is suitable for the fumigation of food commodities such as dried fmits, grain, flour, and nuts, and the faciHties in which these foods are processed or stored, as weU as for tobacco and many kinds of nursery stock. The usual dosage is 2—4 kg/28 m for 12—24 h. In soil fumigation methyl bromide controls weed seeds, nematodes, wireworms, and soil fungi. The usual dosage is 0.5—1 kg/9 m for 24 h at 16°C and above (82). 

Decision allocating production and import quotas for methyl bromide, import quotas for hydrobromofluorocarbons and consumption quotas for hydrochlorofluorocarbons for the period 1 January to 31 December 1995... 

With more than 30 million organic compounds now known and thousands more being created daily, naming them all is a real problem. Part of the problem is due to the sheer complexity of organic structures, but part is also due to the fact that chemical names have more than one purpose. For Chemical Abstracts Service (CAS), which catalogs and indexes the worldwide chemical literature, each compound must have only one correct name. It would be chaos if half the entries for CH3B1 were indexed under "M" for methyl bromide and half under "B" for bromomethane. Furthermore, a CAS name must be strictly systematic so that it can be assigned and interpreted by computers common names are not allowed. 

H.W. Biermann and T. Barry, Evaluation of Charcoal Tube and SUMM A Canister Recoveries for Methyl Bromide Air Sampling, Report EH 9902, Cahfomia Environmental Protection Agency, Department of Pesticide Regulation, Sacramento, CA (1999). 

EPA. 1986b. Health and environmental effects profile for methyl bromide. Cincinnati, OH U.S. Environmental Protection Agency, Office of Health and Environmental Assessment. ECAO-CIN-P182. EPA/600/X-86/171. 

Kato N, Morinobu S, Ishizu S. 1986. Subacute inhalation experiment for methyl bromide in rats. Ind Health 24 87-103. 

Toxicological studies in animals indicate a steep concentration-response curve for methyl bromide and clear species and sex differences in sensitivity. Inhalation exposure up to 120ppm 6 hours/day for 13 weeks resulted in 17 % mortality in male mice but no mortality in female mice or rats of either sex. No methyl bromide-induced histologic lesions were observed in either species, including mice... 

The 2003 ACGIH threshold limit valuetime-weighted average (TLV-TWA) for methyl bromide is Ippm (3.89mg/m ) with a notation for skin absorption. 

These data also demonstrate the impact of bromine chemistry on the stratosphere (see Chapter 12.D). The initial ODP for methyl bromide is 15, due primarily to the large a factor associated with bromine chemistry. However, since it is removed by reaction with OH in the troposphere as well as by other processes such as hydrolysis in the oceans and uptake by soils and foliage (see Chapter 12.D), it has a short atmospheric lifetime of 1.3 years and hence the ODP decreases rapidly with time, toward a long-term steady-state value. 

Fig. 32. Radiation yields of methyl radicals, O, and propane, , (species per 100 eV of radiation absorbed) measured at different concentrations of the ions in cyclohexane. Solid curves are a fit of the experimental points to eqn. (174) with Gg = 0.1, Ggj = 3.8 and a — 0.4 mol dm3 for cyclopropane scavenger, and Gfi = 0.12, Gg, = 3.8 and a —16 mol dm for methyl bromide scavenger. After Rzad and Warman [366], Warman and Rzad [367] and Rzad et al. [369],...

The predicted kinetic behavior is first order. Second order kinetic behavior is actually observed for methyl bromide hydrolysis, so the proposed mechanism cannot be correct. 

There is no antidote for methyl bromide and patients are treated symptomatically. Although there is no specific laboratory data to detect the presence of or diagnose an exposure to methyl bromide, serum bromide levels may be used to document that an exposure occurred. Bromide levels do not aid in the acute treatment of an exposure and do not accurately predict clinical course. 

Draw a reasonable Lewis structure for methyl bromide, CH3Br, which is an ozone depleting gas used as a fumigant. 

TABLE 5-1 Occupations and other environments at risk for methyl bromide exposure... 

The c coefficients measure the substrate response to nucleophilicity, dY, and electrophilicity, d2. Again, 80% aqueous ethanol was chosen as the standard solvent, and a set of c values was chosen in accord with supposed mechanistic behavior of model substrates cY = 3c2 for methyl bromide, = c2 for tert-butyl chloride, and 3cx = c2 for (C6H5)3CF. This approach was largely unsuccessful, probably in large part because tert-butyl chloride is assumed to be equally sensitive to nucleophilicity and ionizing power (29). The equation predicts, for example, that tertiary, benzhydryl, and bridgehead substrates are more sensitive to solvent nucleophilicity than typical primary and secondary SN2 substrates (31). 

The TiOa-supported Pt catalyst is more active for the oxidation of CO and non-halogenated VOC s than for methyl bromide. As shown in Figure 2, at 300°C almost complete conversion was observed for CO, methyl acetate, and benzene. However, only about 20% methyl bromide was converted at 300°C. 

On the other hand, the ZrOz-supported Pt catalyst has a significandy higher activity for methyl bromide oxidation. Figure 3 shows that almost 90% of methyl bromide was converted at 300°C. Higher conversion was also observed for CO and methyl acetate. However, benzene conversion was lower on Pt/ZrOa compared to Pt/TiOa. Some by-products such as monobromobenzene were also observed on 1% Pt/ZrOa at 300°C. 

Nucleophilicities relative to a standard solvent can be quantified by the Swain-Scott equation (12)66, in which k and k0 are the second-order rate constants for reactions of the nucleophile and solvent respectively, and s is a measure of the sensitivity of the substrate to nucleophilicity n. By this definition, the nucleophilicity of the solvent is zero. For all reactions examined, there will be competition between attack by solvent (present in large excess) and reaction with added anionic nucleophiles. Hence, only n values well above zero can be obtained with satisfactory reliability. In the original work66, the solvent was water and all but one of the substrates were neutral s was defined as 1.0 for methyl bromide and was calculated to be 0.66 for ethyl tosylate the lowest reliable n value reported was 1.9 for picrate anion, but a value of < 1 for p-tosylate anion was reported66 in a footnote. 

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