Bromine-silver® oxide

Bromine-Silver oxide. The reaction of bromine in the presence of a silver salt, usually the oxide, with a tertiary alcohol gives in good yield a product of the insertion of oxygen. Thus 1,3,3-trimethylcyclohexanol (1) is transformed into the bicyclic ether (4) in 75% irield. It is suggested that the reaction proceeds through the hypo-bromite (2), the decomposition of which is catalyzed by silver ions. 

Oxidation of saligenin with chromic acid or silver oxide yields saUcyladehyde as the first product. Further oxidation results in the formation of sahcyhc acid, which is also obtained when saligenin is heated with sodium hydroxide at 200—240°C. Chlorination of an aqueous solution of the alcohol gives 2,4,6-trichlorophenol, and bromination in an alkaline medium yields 2,4,6-tribromophenol and tribromosaligenin. When saligenin is heated with one mole of resorcinol in the presence of anhydrous zinc chloride, 3-hydroxyxanthene forms. 

Acids nd Sa.lts. The oxygen acids of bromine are strong oxidants but at ordinary temperatures are stable only in solution. An aqueous solution of hypobromous acid [13517-11-8] may be prepared by treating bromine water with silver oxide or mercuric oxide (69) ... 

Campaigne et al. have used 3-thenyl bromide obtained by benzoyl peroxide-catalyzed, side-chain bromination of 3-methylthiophene with A -bromosuccinimide, as a starting material for 3-substituted thiophenes. - 22 3-Methylthiophene is now prepared commercially from itaconic acid. The reactive halogen in 3-thenyl bromide could be directly reacted with a variety of nucleophiles, such as cyanide, or malonate, to give more complex 3-substituted compounds. 3-Thenyl bromide was converted by the Sommelet reaction to 3-thio-phenealdehyde which, with silver oxide, was oxidized to 3-thio-... 

In recent studies, we found that primary and secondary amines, alone or somehow faster in the presence of the soft Lewis acid Ag+ (refs. 7-9) substitute the bromine in (S)-2-bromopropanamides, in an organic solvent, at room temperature, and yield N-alkyl-, and N,N -dialky 1-aminopropanamides, with inversion of configuration and high enantiomeric excess. Conversely, in the presence of silver oxide (Ag20), much faster reactions occur with retention of configuration, giving... 

We developed a convenient synthesis of 3-cyclopentenyl hydroperoxide via hydro-boration and autoxidation of cyclopentadiene, and bromination proceeded smoothly to afford 32 40). Ring closure with silver trifluoroacetate (Eq. 26) afforded a 5-bromo-2,3-dioxabicyclo[2.2.1]heptane 34 (6%) and a 5-trifluoroacetoxy-2,3-dioxabicyclo-[2.2.1]heptane 35 (14%), and it was shown independently that 34 is rapidly converted into 35 by reaction with Ag02CCF3. To avoid the trifluoroacetate bromide substitution that accompanies and competes with the dioxabicyclization, 32 was treated with silver oxide and this slowly yielded an isomeric 5-bromo-peroxide 33 (42 %) (Eq. 26). 

Bromination afforded a mixture of /rans-3-cw-4-dibromide 38 (65 %) and cis-3-trans-4-dibromide 39, and the reaction of each of these with silver oxide and with silver trifluoroacetate was carried out (Eq. 30). 

L-dihydroxy-succinic acid (L(dexiro)-tartaric acid, CXIII). This result establishes the position of the double bond between C4 and C5 and demonstrates that C4 carries only one hydrogen atom while C5 has attached to it the enolic hydroxyl group. Treatment of the enol CXI with ethereal diazomethane gives 5-methyl-A4-D-glucosaccharo-3,6-lactone methyl ester (CXIY) which upon further methylation with silver oxide and methyl iodide yields 2,5-dimethyl-A4-D-glucosaccharo-3,6-lactone methyl ester (CXV). When the latter is subjected to ozonolysis there is formed oxalic acid and 3-methyl-L-threuronic acid (CXVI). Oxidation of this aldehydic acid (CXYI) with bromine gives rise to a monomethyl derivative (CXVII) of L-ilireo-dihydroxy-succinic acid. 

Methylation of X with silver oxide and methyl iodide gave the lactone of methyl 2,5-dimethyl-j8-D-glucofururonoside (XIII) which was characterized by its conversion to the crystalline amide (XIV). Further methylation of XIII, form, with methyl sulfate and sodium hydroxide gave methyl 2,3,5-trimethyl-/3-D-glucofururonoside (XVI) from which by hydrolysis of the glycosidic methyl group and subsequent oxidation with bromine, there was obtained 2,3,5-trimethyl-D-glucosaccharolactone (XVII) characterized by the formation of its crystalline methyl ester. 

Bromo-pentammino-rhodium Bromide, [Rh(NH3)5Br]Br2, is prepared in a similar manner to the cliloro-salt by heating rhodium-zinc alloy with a mixture of bromine and hydrobromic acid, or by warming aquo-pentammino-rhodium bromide with excess of hydrobromic acid to 100° C.1 2 It separates in small orthorhombic yellow crystals which are almost insoluble in cold water and insoluble in alcohol and hydrobromic acid. It has the same constitution as the ehloro-compound. Treated with nitric acid, hydrochloric acid, or silver carbonate, it yields the corresponding salts respectively, and with moist silver oxide yields an unstable hydroxide, [Rh(NIT3)5Br](OH)2. The methods from the preparation of the bromo-salts are like those for the ehloro-salts. 

A. J. Balard,9 in 1821, also prepared hypobromous acid in a similar manner, namely, by the gradual addition of mercuric oxide of bromine water, and thoroughly shaking the mixture after each addition. Further, quantities of bromine and mercuric oxide can be added until the yellow fluid contains between 6 and 7 parts of HOBr per 100 c.c. The mercuric oxide can be replaced by silver oxide, silver or mercuric nitrate, mercuric acetate, etc. The soln. with 6-7 parts of HOBr per 100 c.c. decomposes at 30°, but more dil. soln. when distilled under ordinary atm. press, give a distillate of bromine followed by a straw-yellow fraction which is a dil. aq. soln. of hypobromous acid. The decomposition is not so pronounced if it be conducted at 40° under a press, of, say, 50 mm. of mercury. 

A. J. Balard 8 prepared an olive-green insoluble mass by the action of bromine water on copper oxide, vegetable colours are not bleached, but nitrogen is evolved from ammonia, and carbonic and other acids set free bromine. When heated, oxygen, bromine, and water are given off, and copper oxybromide remains. The solid is possibly a mixture of bromine and copper oxybromide and not copper hypobromite. A. J. Balard also prepared a soln. which probably contained silver hypobromite by the action of bromine water on silver oxide. The product easily decomposes into bromide and bromate. F. W. Schmidt suggested that the white floccuient precipitate obtained by the action of iodine on a very dil. ammoniacal soln. of silver nitrate is possibly silver hypoiodite. 

When acetobromoglucose was treated with moist silver oxide, a mixture of bromine-free acetates was formed from which was obtained, besides glucose tetraacetate, a small proportion of a crystalline disaccharide octa-... 

The interaction of diaryl tellurides and the esters of halogenated fatty acids, e.g. methyl bromacetate, gives diarvl-telluretin halide alkyl esters, e.g. (C6H5)2Te(Br).CH2.COOCH3. The halogen present may be chlorine, bromine or iodine, moist silver oxide replacing the bromine by the hydroxyl group. 

Diphenyl-telluretin, (C6H5)2Te(OH).CH2.COOH.—The preceding bromide, when treated with moist silver oxide, exchanges its bromine for the hydroxyl group. The product sinters at 100° C., melts at 117° to 118° C., dissolves readily in warm chloroform, but is insoluble in benzene, toluene, ligroin or ether. It forms salts with acids. 

The bromine atom of chromium pentaphenyl bromide is also replaced by the hydroxyl group when the compound is shaken in chloroform solution with an aqueous suspension of silver oxide. The other products present in the crude bromide remain dissolved in the chloroform, but since silver oxide seems to exert an oxidising action a mixture of bases results, and not pure chromium pentaphenyl hydroxide as might be anticipated. 

The addition of bromine to the hexaacetyllactal leads to a mixture of dibromides, from which one that is apparently homogeneous could be isolated.47 Two chlorine atoms could also be added.48 The halogen in the 1-position can be replaced easily by the action of moist silver oxide or silver carbonate, and hexaacetyl-2-desoxy-2-halogeno-lactose (or epi-lactose) is formed. This compound can be converted with lead oxide to the 2-desoxylactobionic acid.49... 

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