Methyl bromide solutions

Current work in our laboratory [3] indicates that in methyl bromide solution the ionogenic reaction is of second order with respect to [AlBr3], and the same has been found [14] for the ionisation of A1I3, Gal3, and Inl3 in EtI. Since it is known that the aluminium halides are monomeric in these solutions, it follows that the rate-determining step for the selfionisation is the reaction (10) ... 

In a 3-1. three-necked flask, equipped with a sealed mechanical stirrer, reflux condenser, and a pressure-equalizing separatory funnel (Note 3), are placed 48 g. (2 g.-atoms) of magnesium turnings, 500 ml. of anhydrous ether, and a small crystal of iodine. The cold methyl bromide solution is transferred to the separatory funnel and slowly added, with stirring. The reaction starts spontaneously, and the remainder of the methyl bromide is added at a rate such that the solution boils gently under reflux, (ienerally, the addition is complete at the end of 1 2 hours and all the magnesium should be dissolved. Alter the stirred solu-... 

The separatory funnel is fitted to an adapter tube extending to the bottom of the flask so that the methyl bromide solution is introduced below the surface of the mixture. A drying tube is placed in the condenser outlet. 

DIPHENYLMETHOXYTROPANE METHANESULFONATE see TNUOOO DIPHENYLMETHYL BROMIDE pOT) see BNG750 DIPHENYL METHYL BROMIDE, solution pOT) see BNHOOO... 

A solution of methylmagnesium bromide in 150 ml of diethyl ether, prepared from 0.5 mol of methyl bromide (see Chapter II, Exp. 5) was subsequently added in 20 min with cooling at about 20°C. After the addition the mixture was warmed for 2 h under reflux (the thermometer and gas outlet were replaced with a reflux condenser), a black slurry being formed on the bottom of the flask. The mixture was cooled in a bath of dry-ice and acetone and a solution of 30 g of ammonium chlori.de in 200 ml of water was added with vigorous stirring. The organic layer and four ethereal extracts were combined, dried over potassium carbonate and subsequently concentrated in a water-pump vacuum. Careful distillation of the residue through a 40-cm... 

A solution of methyl ithium in ether is prepared from lithium wire and methyl bromide according to the literature procedure, and titrated by the same method as Note 6. The checkers used 1.1 M methyl ithium from Aldrich. 

Although ethereal solutions of methyl lithium may be prepared by the reaction of lithium wire with either methyl iodide or methyl bromide in ether solution, the molar equivalent of lithium iodide or lithium bromide formed in these reactions remains in solution and forms, in part, a complex with the methyllithium. Certain of the ethereal solutions of methyl 1ithium currently marketed by several suppliers including Alfa Products, Morton/Thiokol, Inc., Aldrich Chemical Company, and Lithium Corporation of America, Inc., have been prepared from methyl bromide and contain a full molar equivalent of lithium bromide. In several applications such as the use of methyllithium to prepare lithium dimethyl cuprate or the use of methyllithium in 1,2-dimethyoxyethane to prepare lithium enolates from enol acetates or triraethyl silyl enol ethers, the presence of this lithium salt interferes with the titration and use of methyllithium. There is also evidence which indicates that the stereochemistry observed during addition of methyllithium to carbonyl compounds may be influenced significantly by the presence of a lithium salt in the reaction solution. For these reasons it is often desirable to have ethereal solutions... 

A. Triphenylmethylphosphonium bromide. A solution of 55 g. (0.21 mole) of triphenylphosphine dissolved in 45 ml. of dry benzene is placed in a pressure bottle, the bottle is cooled in an ice-salt mixture, and 28 g. (0.29 mole) of previously condensed methyl bromide is added (Note 1). The bottle is sealed, allowed to stand at room temperature for 2 days, and is reopened. The white solid is collected by means of suction filtration with the aid of about 500 ml. of hot benzene and is dried in a vacuum oven at 100° over phosphorus pentoxide. The yield is 74 g. (99%), m.p. 232-233°. 

With magnesium methyl bromide tuberostemonine gives a product, which on treatment with ammonium chloride solution yields a substance (a), C24H4JO4N, m.p. 110-2 , but with dilute sulphuric acid, furnishes the dehydrated compound, (b) C24H3903N, m.p. 164 . The results of this reaction are represented as follows —... 

Swain and Eddy have queried the wide applicability of the S l and Sif2 mechanisms and favored a push-pull termolecular process for the reaction of pyridine with methyl bromide in benzene solution for example, they have suggested that the effects observed on the addition of methanol, phenol, p-nitrophenol, and mercuric bromide to the reaction mixture can be explained by an intermediate of type 168. ... 

More expedient from the preparative point of view is the method based on compounds 6, which can be obtained in high yields by the addition of bromine to (3-methyltellurovinylaldehydes [96ZOK1434 97JOM(536-537)233], When treated in benzene solution with ammonia, (3-methyldibromotellurovinylaldehydes 6 afford isotellurazoles lg,h in about 70% yields [97DOK(357)504], The key step of the reaction is the elimination of a molecule of methyl bromide from the intermediate imine 7. 

Triphenylmethylphosphonium bromide A pressure bottle is charged with a solution of 55 g (0.21 mole) of triphenylphosphine in 45 ml of dry benzene and cooled in an ice-salt bath. A commercially available ampoule of methyl bromide is cooled below 0° (ice-salt bath), opened, and 28 g (0.29 mole, approx. 16.2 ml) is added to the bottle in one portion. The pressure bottle is tightly stoppered, brought to room temperature, and allowed to stand for 2 days. After this time, the bottle is opened and the product is collected by suction filtration, the transfer being effected with hot benzene as needed. The yield of triphenylphosphonium bromide is about 74 g (99%), mp 232-233°. This material should be thoroughly dried (vacuum oven at 100°) before use in preparing the ylide. 

Preparation of the Methyl Bromide To the acetone solution of the free base was added an acetone solution, containing an excess of methyl bromide. Within a few minutes the methobromide started to crystallize. The mixture was allowed to stand for several hours. The crystallized solid was filtered, and additional product was obtained by evaporation of the filtrate. The yield was nearly quantitative. After recrystallization from acetone, the product melted at 329°C. 

Benziloyloxy-1-azabicyclo[2.2.2] octane methobromide was prepared by adding 20 cc of a 30% solution of methyl bromide in ether to a solution of 2.5 g of 3-benziloyloxy-1-azabicyclo[2.2.2] octane in 20 cc of chloroform. After standing for 3 hours at room temperature and 15 hours at -i-5°C, a crystalline precipitate had formed. This was filtered off and recrystallized from a mixture of methanol, acetone, and ether prisms melting at 240° to 241°C. 

The methyl bromide quaternary was prepared by saturating a solution of the base in dry ethyl acetate with methyl bromide. After standing for 9 days the resulting crystalline solid was filtered and recrystallized from butanone and from ethyl acetate MP 193° to 194.5°C. 

J/3,5a,6(3- Trihydroxy-6oi, 17a-Dimethyl-17 -Carbometboxyandrostane (IV) 3(3-Acetoxy-5a-hydroxy-17a-methyl-17/3-carbomethoxyandrostan-6-one (III, 1.004 g) is dissolved in dry benzene (25 ml) and methyl magnesium bromide solution in ether (3M, 10 ml) is added. 

Alternatively, 25.0 g of either 3j3,5a-dihydroxy-17a-methyl-17j3-carbomethoxyandrostan-6-one (Ilia) or 25.0 g of its 3)3-acetate (Hlb), are dissolved in dry tetrahydrofuran (1,250 ml, freshly distilled over lithium aluminum hydride) and dry benzene (2,000 ml) is added. Methyl magnesium bromide in ether solution (3 M, 750 ml) is added to the stirred solution and the resulting mixture is stirred at room temperature for 16 hours. An additional quantity of methyl magnesium bromide solution in ether (2M, 375 ml) is added, and 1,250 ml of the solvent mixture are distilled off. The resulting mixture is refluxed for 5 hours and worked up as described above, yielding compound (V) as a colorless oil. 

Methyl bromide (17 grams) was added to a solution of the bis-piperidinodiacetate (4 grams) in methylene chloride (10 ml) and the resulting solution allowed to stand at room temperature for 4 days. The solution was evaporated to dryness, the residue triturated with ether, and filtered to give the bis-methobromide (5.2 grams), MP 206°C. Recrystallization from acetone-methylene chloride gave material MP 214°-217°C. 

Methyl bromide is a compound in which the chemical bonds are predominantly covalent. An aqueous solution of methyl bromide does not conduct electricity, hence it does not form ions (such as CH and Br ions) in aqueous solutions. 

When 1-methyl-, 1,2- and 1,3-dimethyl-indoles were oxidized on a platinum electrode in methanolic ammonium bromide solution, in addition to the oxidation products, products of nuclear bromination at the 3-and 5-positions were observed. 1,2- Dimethylindole (20) gave 3-bromo-1,2-dimethylindole (81CCC3278) [bromine in chloroform gave the same product (85CHE786)]. In acidic conditions the amidinium cation formed from 20 was brominated in the 5-position (Scheme 14). Acylated 2-aminoindoles reacted similarly in neutral media to give 3-bromo derivatives and when protonated to give 5-bromo products. Bromine in chloroform transformed l-methyl-2-dimethylaminoindole (21) into the 3-bromo derivative (85CHE782) (Scheme 15). 

These values, from Ref. 17. derive from methyl bromide in aqueous solution. 

Lord and Pawliszyn" developed a related technique called in-tube SPME in which analytes partition into a polymer coated on the inside of a fused-silica capillary. In automated SPME/HPLC the sample is injected directly into the SPME tube and the analyte is selectively eluted with either the mobile phase or a desorption solution of choice. A mixture of six phenylurea pesticides and eight carbamate pesticides was analyzed using this technique. Lee etal. utilized a novel technique of diazomethane gas-phase methylation post-SPE for the determination of acidic herbicides in water, and Nilsson et al. used SPME post-derivatization to extract benzyl ester herbicides. The successful analysis of volatile analytes indicates a potential for the analysis of fumigant pesticides such as formaldehyde, methyl bromide and phosphine. 

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