Methyl bromide, oxidation

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. 

A new approach we found is based on the initial bromination of methane to methyl bromide, which can be effected with good selectivity, although still in relatively low yields. Methyl bromide is easily separated from exeess methane, whieh is readily recyeled. Hydrolysis of methyl bromide to methyl alcohol and its dehydration to dimethyl ether are readily achieved. Importantly, HBr formed as by produet ean be oxidatively reeycled into bromine, making the overall proeess cat-alytie in bromine. 

TetrabromobisphenoIA. Tetrabromobisphenol A [79-94-7] (TBBPA) is the largest volume bromiaated flame retardant. TBBPA is prepared by bromination of bisphenol A under a variety of conditions. When the bromination is carried out ia methanol, methyl bromide [74-80-9] is produced as a coproduct (37). If hydrogen peroxide is used to oxidize the hydrogen bromide [10035-10-6] HBr, produced back to bromine, methyl bromide is not coproduced (38). TBBPA is used both as an additive and as a reactive flame retardant. It is used as an additive primarily ia ABS systems, la ABS, TBBPA is probably the largest volume flame retardant used, and because of its relatively low cost is the most cost-effective flame retardant. In ABS it provides high flow and good impact properties. These benefits come at the expense of distortion temperature under load (DTUL) (39). DTUL is a measure of the use temperature of a polymer. TBBPA is more uv stable than decabrom and uv stable ABS resias based oa TBBPA are produced commercially. 

In a further development on this theme, the thiol, 153, is first alkylated to the corresponding benzyl ether (158). Treatment with sodium methoxide removes the proton on the amide nitrogen to afford the ambient anion (159). This undergoes alkylation with methyl bromide on the ring nitrogen thus it locks amide into the imine form (160). Chlorolysis serves both to oxidize the sulfur to the sulfone stage and to cleave the benzyl ether linkage there is thus obtained the sulfonyl chloride, 161. 

Isobutylene, methyl chloride, methyl bromide, ethyl chloride (Linde Div. Union Carbide Corp.) were obtained in high purity and were further purified by passing through a column containing barium oxide and molecular sieves. 

The nucleophilicity of the organocuprate cluster derives mainly from the filled copper 3d orbital, in combination with the carbon orbital associated with bonding to copper. These orbitals for the TS for reaction with methyl bromide and ethylene oxide are shown in Figure 8.4. 

Fig. 8.4. Representation of the orbital involved in C-Cu bond formation in the reaction of (CH3)2CuLi-LiCl with methyl bromide (left) and ethylene oxide (right). Reproduced from J. Am. Chem. Soc., 122, 7294 (2000), by permission of the American Chemical Society.

The rate-determining step in this process is the oxidative addition of methyl iodide to 1. Within the operating window of the process the reaction rate is independent of the carbon monoxide pressure and independent of the concentration of methanol. The methyl species 2 formed in reaction (2) cannot be observed under the reaction conditions. The methyl iodide intermediate enables the formation of a methyl rhodium complex methanol is not sufficiently electrophilic to carry out this reaction. As for other nucleophiles, the reaction is much slower with methyl bromide or methyl chloride as the catalyst component. 

Rasche et al. [410] reported that some terrestrial and marine nitrifiers had the capacity to oxidize methyl bromide to formaldehyde and bromide ion. They concluded that ammonia monooxygenase produced by the nitrifiers, which catalyzes the oxidation of ammonia to hydroxylamine, was responsible for the oxidation of methyl bromide to formaldehyde. 

Oremland et al. [136] subsequently demonstrated that methane-oxidizing bacteria also had the capacity to co-oxidize methyl bromide by methane monooxygenase produced during the oxidation of methane to methanol. They also showed that methanotrophic soils that had a high capacity to oxidize methane degraded14C-labeled methyl bromide to 14C02. 

Sikov MR, Cannon WC, Carr DB. 1980. Teratologic assessment of butylene oxide, styrene oxide and methyl bromide. Report to National Institute for Occupational Safety and Health, Division of Biomedical and Behavioral Science, U.S. Department of Health, Education and Welfare, Cincinnati, OH, by Battelle, Pacific Northwest Laboratory, Richland, WA. NTIS No. PB81-168510. 

Indenopyrene, see Indeno[l,2,3-crf pyrene l//-Indole, see Indole Indolene, see Indoline Inexit, see Lindane Inhibisol, see 1,1,1-Trichloroethane Insecticide 497, see Dieldrin Insecticide 4049, see Malathion Insectophene, see a-Endosulfan, p-Endosulfan Intox 8, see Chlordane Inverton 245, see 2,4,5-T lodomethane, see Methyl iodide IP, see Indeno[l,2,3-crf pyrene IP3, see Isoamyl alcohol Ipaner, see 2,4-D IPE, see Isopropyl ether IPH, see Phenol Ipersan, see Trifluralin Iphanon, see Camphor Isceon 11, see Trichlorofluoromethane Isceon 122, see Dichlorodifluoromethane Iscobrome, see Methyl bromide Iscobrome D, see Ethylene dibromide Isoacetophorone, see Isophorone a-Isoamylene, see 3-Methyl-l-butene Isoamyl ethanoate, see Isoamyl acetate Isoamylhydride, see 2-Methylbutane Isoamylol, see Isoamyl alcohol Isobac, see 2,4-Dichlorophenol Isobenzofuran-l,3-dione, see Phthalic anhydride 1,3-Isobenzofurandione, see Phthalic anhydride IsoBuAc, see Isobutyl acetate IsoBuBz, see Isobutylbenzene Isobutane, see 2-Methylpropane Isobutanol, see Isobutyl alcohol Isobutene, see 2-Methylpropene Isobutenyl methyl ketone, see Mesityl oxide Isobutyl carbinol, see Isoamyl alcohol Isobutylene, see 2-Methylpropene Isobutylethylene, see 4-Methyl-l-pentene Isobutyl ketone, see Diisobutyl ketone Isobutyl methyl ketone, see 4-Methyl-2-pentanone Isobutyltrimethylmethane, see 2,2,4-Trimethylpentane Isocumene, see Propylbenzene Isocyanatomethane, see Methyl isocyanate Isocyanic acid, methyl ester, see Methyl isocyanate Isocyanic acid, methylphenylene ester, see 2,4-Toluene-diisocyanate... 

Mole-nots, see Strychnine Mollan 0, see Bis(2-ethylhexyl) phthalate Mondur TD, see 2,4-Toluene diisocyanate Mondur TD-80, see 2,4-Toluene diisocyanate Mondur TDS, see 2,4-Toluene diisocyanate Monobromobenzene, see Bromobenzene Monobromobenzol, see Bromobenzene Monobromoethane, see Ethyl bromide Monobromomethane, see Methyl bromide Monobromotrifluoromethane, see Bromotrifluoromethane Monobutylamine, see Butylamine Mono-n-butylamine, see Butylamine Monobutyl ethylene glycol ether, see 2-Butoxyethanol Monochlorbenzene, see Chlorobenzene Monochlorethane, see Chloroethane Monochloroacetaldehyde, see Chloroacetaldehyde Monochlorobenzene, see Chlorobenzene Monochlorodibromomethane, see Dibromochloromethane Monochlorodiphenyl oxide, see 4-Chlorophenyl phenyl ether... 

Goodwin, K.D., Schaefer, J.K., and Oremland, R.S. Bacterial oxidation of dibromomethane and methyl bromide in natural waters and enrichment cultures, AppL Environ. Microbiol, 64(12) 4629-4636, 1998. 

Sikov MR, Cannon WC, Carr DB Teratologic Assessment of Butylene Oxide, Styrene Oxide and Methyl Bromide. DHHS (NIOSH) Pub No 81-124. US Department of Health and Human Services, July 1981... 

Bromine occurs in nature as bromide in many natural brine wells and salt deposits. It also is found in seawater at a concentration of 85 mg/L. The element was discovered by A. J. Balard and C. Lowig, independently in 1826. Bromine is used in bleaching fibers and as a disinfectant for water purification. Other appbcations are in organic synthesis as an oxidizing or brominat-ing agent in the manufacture of ethylene dibromide, methyl bromide and other bromo compounds for dyes and pharmaceutical uses as a fire retardant for plastics and in chemical analysis. Ethylene dibromide is used in anti-... 

Hallier, E., Langhof, T., Dannappel, D., Leutbecher, M., Schoder, K., Goergens, H.W., Muller, A. Bolt, H.M. (1993) Polymorphism of glutathione conjugation of methyl bromide, ethylene oxide and dichloromethane in human blood influence on the induction of sister chromatid exchanges (SCE) in lymphocytes. Arch. Toxicol., (tL, 173-178... 

Sikov, M.R., Cannon, W.C., Carr, D.B., Miller, R.A., Montgomery, L.F. Phelps, D.W. (1981) Teratologic Assessment of Butylene Oxide, Styrene Oxide and Methyl Bromide, Cincinnati, OH, United States Department of Health and Hrunan Services, Public Health Service, Centers for Disease Control, National Instute for Occupational Safety and Health... 

Hydrocarbon formation from methyl chloride can be catalyzed by ZSM-5482 483 or bifunctional acid-base catalysts such as W03 on alumina.420,447 The reaction on ZSM-5 gives a product distribution (43.1% aliphatics and 57.1% aromatics at 369°C) that is very similar to that in the transformation of methanol, suggesting a similar reaction pathway in both reactions.483 W03 on A1203 gives 42.8% C2-C5 hydrocarbons at 327°C at 36% conversion.447 When using methyl bromide as the feed, conversions are comparable. However, in this case, HBr can be very readily air-oxidized to Br2 allowing a catalytic cycle to be operated. Since bromine is the oxidant, the reaction is economical. The one step oxidative condensation of methane to higher hydrocarbons was also achieved in the presence of chlorine or bromine over superacidic catalysts.357... 

Fumigant -calcium cyanide as [CYANIDES] (Vol 7) -ethylene oxide as [ETHYLENE OXIDE] (Vol 9) -methyl bromide as [BROMINE COMPOUNDS] (Vol 4) -phosphine as [PHOSPHINE AND ITS DERIVATIVES] (Vol 18)... 

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