Acetate silver, reaction with bromine

Ag2Se (c, II). Fabre2 measured the heats of reaction of silver selenide with bromine water and of aqueous silver acetate with gaseous hydrogen selenide. See also Pelabon1 and Tubandt and Reingold.1... 

The conversion of 5a-cholestan-6/5-ol into the 6yS, 19-epoxide, by reaction with bromine and silver oxide, has been improved by the use of certain silver salts with bromine in pentane, in the dark. Silver acetate, carbonate, and... 

Reactions in acetic anhydride with metal acetates present probably occur by 1,4-addition of bromonium acetate (85CHE458). When NBS in sulfuric acid at 20°C was used, the product ratio resembled that observed with bromine-sulfuric acid-silver sulfate. At 60°C the ratio changed to 2 1.2 1 as a consequence of more extensive dibromination (88CHE892) (Scheme 33). As might have been deduced, 2-(2 -thienyl)quinoline was brominated only in the thiophene ring (82CHE28). 

A kinetic isotope effect, kH/kD = 1.4, has been observed in the bromination of 3-bromo-l,2,4,5-tetramethylbenzene and its 6-deuterated isomer by bromine in nitromethane at 30 °C, and this has been attributed to steric hindrance to the electrophile causing kLx to become significant relative to k 2 (see p. 8)268. A more extensive subsequent investigation304 of the isotope effects obtained for reaction in acetic acid and in nitromethane (in parentheses) revealed the following values mesitylene, 1.1 pentamethylbenzene 1.2 3-methoxy-1,2,4,5-tetramethyl-benzene 1.5 5-t-butyl-1,2,3-trimethylbenzene 1.6 (2.7) 3-bromo-1,2,4,5-tetra-methylbenzene 1.4 and for 1,3,5-tri-f-butylbenzene in acetic acid-dioxan, with silver ion catalyst, kH/kD = 3.6. All of these isotope effects are obtained with hindered compounds, and the larger the steric hindrance, the greater the isotope... 

In another study,125 methyl 5-0-benzoyl-2,3-dideoxy-/8 D-g(t/cero-pent-2-enofuranoside (81) was treated with bromine in methanol in the presence of silver acetate and barium carbonate the two monobenzoates (shown as 84) of methyl 2-bromo-2-deoxy-j8-D-xylofurano-side were obtained. A rationalization for this reaction involves formation of an intermediate bromonium ion (82), produced by attack of Br on the less-hindered side of the double bond, which then undergoes trans-attack by the benzoate group at C-5 to give the benzoxonium intermediate (83) the monobenzoates (84) are obtained on processing of the reaction mixture with water. 

Lemieux and Fraser-Reid174 have reported that the reaction of methyl 3,4,6-tri-0-acetyl-2-deoxy-2-iodo-j3-D-glucopyranoside (137) with bromine and silver acetate in acetic acid containing potassium acetate gives an almost quantitative yield of 1,3,4,6-tetra-O-acetyl-2,5-anhydro-D-mannose methyl hemiacetal (139), obtained as an... 

Treatment of the steroid derivative 1 with bromine and silver acetate in a mixture of chloroform and pyridine at low temperature followed by quenching of the reaction mixture with aqueous acid gave a mixture of compounds, one of which was shown to be 2. 

AUylic acetoxylation. Some years ago Petrow reported that the reaction of dehy-droisoandrosterone (1) with bromine and silver acetate resulted in acetoxylation at C4 to give 2. The reaction proceeds via the 5a,6p-dibromide (a). The same reaction is observed... 

Aliphatic nitroso compounds can be prepared from IV-alkylhydioxylamines oxidation widi bromine, chlorine or sodium hypochlorite in weakly acidic solution, reaction with potassium dichromate in acetic or sulfuric acid, and by oxidation widi yellow mercury(II) oxide in suspension in an organic solvent. Silver carbonate on Celite has also been used to prepare aliphatic nitroso compounds, such as ni-trosocyclohexane, in high yield from the corresponding hydroxylamines." Aqueous sodium periodate and tetraalkylanunonium periodates, which are soluble in organic solvents, are the reagents most commonly used for the oxidation of hydroxamic acids and IV-acylhydroxylamines to acylnitroso compounds... 

Alkoxy radicals produced by homolysis of hypohalites can attack non-activated C-H bonds, and lead to tetrahydro-furanoid structures after basic treatment of the intermediate halo-alcohols. Hypochlorites of [2y,2g] and C(20)-tertiary alcohols [28,2gJ gave 6 8,19- and 18,20-oxido derivatives respectively on irradiation and hydrolysis, but the more reactive hypobromites and hypoiodites are now preferred. Akhtar ef al. [30] distinguish between two modes of reaction of a 6jS-hypobromite (2), generated in situ by treating the alcohol with bromine and silver acetate. Experiments with... 

TOLUOL (108-88-3) C7H, CsHjCHj Forms explosive mixture with air [explosion limits in air (vol %) 1.4 to 6.7 flash point 39°F/4°C cc autoignition temp 896°F/480°C Fire Rating 3]. Violent reaction with strong oxidizers, bromine, bromine trifluoride, chlorine, hydrochloric acid-sulfuric acid mixture, l,3-dichloro-5,5-dimethyl-2,4-imidazolididione, dinitrogen tetraoxide, fluorine, nitric acid (cone.), nitrogen dioxide, silver chloride, sulfur dichloride, uranium fluoride, vinyl acetate. Forms explosive mixture with strong acids, strong oxidizers, silver perchlorate. 

ACIDE OXALIQUE (French) (144-62-7) Combustible solid. Violent reaction with strong oxidizers, bromine, furfuryl alcohol, hydrogen peroxide (90%), phosphorus trichloride, silver powders, sodium chlorite, sodium hypochlorite. Mixture with some silver compounds forms explosive salts of silver oxalate. Incompatible with caustics, mercury, silver, urea. Attacks polyvinyl alcohol and acetal plastics. 

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