Acetone, bromo

The direct bromination of aliphatic ketones occurs readily, often giving isomeric mixtures. Thus, methyl ethyl ketone and an equimolar quantity of bromine yield the a-btomomethyl (17%) and the a-bromoethyl (50%) isomers polybrominated products are also formed. On the other hand, only the tertiary hydrogen in methyl isopropyl ketone is substituted upon monobromination. By varying the conditions for the bromination of acetone, mono- or poly-substitution products may be formed e.g., bromo-acetone (44%), a,a -dibromoacetone (60%), and a,a,a -tribromoacetone (60%). ... 

Some Observations on the Reactions of Bromo-acetone and Bromo-... 

Lung edema symptoms usually develop several hours later and are aggravated by physical sxsrtlon rest and hospitalization assentlal. As first aid, a doctor or authorized person should consider administering a corticosteroid spray. Bromo acetone is a tear gas. 

The application to the saturated methyl ketone (83) of Wilds method of constructing ring D (Scheme 10) gave derivatives of 16-oxoestrone [188] (see Scheme 6). The alkylation of ketone (83) with bromoacetic ester and the reaction of the chloride of the acid formed (103) with sodiomalonic ester and decarboxylation led to the diketone (104). An attempt at its direct synthesis from ketone (83) by alkylation of the latter with chloro- or bromo-acetone was unsuccessful. The intramolecular cyclization of ketone (104) by the action of alkali yielded the -ketone (107), hydrogenation of which led to the isolation of one isomer of the 16-ketone (106) of unknown configuration [188]. The construction of a side chain at C14 of the methyl... 

Wnte an equation clearly showing the stereochemistry of the starting material and the prod uct for the reaction of (S) 1 bromo 2 methylbutane with sodium iodide in acetone What is the configuration R or S) of the product" ... 

Bromo-3-methyl-4-nitroisothiazole can be converted into the 5-iodo analogue by reaction with sodium iodide in acetone (65AHC(4)107). Halogen exchange also takes place when 4-bromo-3-methylisothiazole-5-diazonium chloride is treated with methyl methacrylate and hydrolyzed, giving the chloro compound (150) (72AHC(14)l). 

The propyne (b.p. —23.2°) is precondensed to the mark in a volumetric flask cooled by acetone-dry ice. Evaporation of some propyne during addition will lead to a moderate molar excess of l-bromo-3-chloropropane, regarded as desirable in preventing formation of diyne product. 

Acetoxyandrost-5-en-17-one (59) is converted into the ethylene ketal (60) by treatment with ethylene glycol, triethylorthoformate and p-toluenesulfonic acid. The ketal is brominated with pyridinium bromide perbromide in THF and then treated with sodium iodide to remove bromine from the 5 and 6 positions. This gives the 16a-bromo compound (61) which is hydrolyzed in methanol to the free alcohol (62). Dehydrobromination is effected with potassium Fbutoxide in DMSO to give the -compound (63). Acid catalyzed hydrolysis of the ketal in aqueous acetone gives the title compound (64). ... 

A suspension of 17a,21-dihydroxypregna-4,9(ll)-diene-3,20-dione 21-acetate (0.77 g) and iV-bromoacetamide (0.3 g) in anhydrous methylene dichloride (40 ml) is added over 2-3 min with stirring to a mixture of anhydrous hydrogen fluoride (10.19 g), and anhydrous tetrahydrofuran (18 g) in a polyethylene bottle at —80° (acetone-dry ice). After 1 hr at —80° the reaction mixture is kept for a further 1 hr at 0° and then added cautiously to an excess of an ice-cold solution of sodium carbonate. Extraction with methylene dichloride and crystallization from acetone-hexane furnish 9a-bromo-ll -fluoro-17a,21-dihydroxypregn-4-ene-3,20-dione 21-acetate (0.69 g), mp 205-208°, raised by several crystallizations from acetone-hexane to 215-217° [aju 142° (CHCI3) max 240-242 mju (e 15,500). 

To a solution of 2a-bromo-5a-cholestan-3-one (7.1 g, 15.2 mmol) in 175 ml dry acetone is added dropwise a solution of potassium ethyl xanthate (2.6 g, 16.2 mmol) in 90 ml acetone. The reaction mixture is stirred at 20° for 12 hr and then evaporated to dryness under vacuum. The resulting solid is treated with 100 ml hexane to dissolve the organic material and the inorganic salts are removed by filtration. The hexane filtrate is concentrated under vacuum and the resulting yellow solid ca. 7.5 g) is crystallized from chloroform-ethanol to give the xanthate (137) as white needles, ca. 5 g mp 114-115°. 

A solution of the bromo ketone (1 g) and sodium iodide (1 g) in 40 ml of acetone is refluxed for 20 min. The hot solution is filtered and the filtrate added to a mixture of 5 g of potassium bicarbonate and 4 ml of acetic acid. This mixture is then refluxed overnight, cooled and poured into a large excess of water. The resulting white precipitate is collected by filtration, dried in vacuo and finally recrystallized twice from methanol to afford 0.49 g of 3, 21-diacetoxypregna-5,16-dien-20-one mp 153-155° [a]jj —40° (CHCI3). 

Bromo-A-homo-estra-4y5 0)-diene-3, l-dione (49). A solution of silver perchlorate (0.55 g, 5 mole-eq) in acetone (2 ml) is added to a refluxing solution of monoadduct (48 0.28 g) in acetone (30 ml) containing water (0.5 ml). After being heated at reflux for 25 min the reaction mixture is cooled and the precipitated silver bromide is removed by filtration, yield about 0.11 g. The filtrate is diluted with water (500 ml) and is thoroughly extracted with chloroform. The chloroform extracts are washed with water and saturated salt solution, dried over anhydrous magnesium sulfate, and evaporated at... 

A-Homo-estra-, 4, )-triene-3, l-dione (50). A solution of bromo ketone (49 0.2 g), silver perchlorate (0.5 g) and 20% aqueous acetone (30 ml) is heated at reflux with stirring for 30 min and then allowed to cool to room temperature. The mixture is filtered to remove precipitated silver bromide (ca. 0.19 g) and the filtrate is diluted with water (200 ml) and then extracted with chloroform. The chloroform extracts are washed, successively with water, 5% sodium bicarbonate solution, water and saturated salt solution. After being dried over anhydrous magnesium sulfate, the solvents are removed at reduced pressure to give a solid. Recrystallization from ethyl acetate gives A-homo-estra-l,4,5(10)-triene-3,17-dione (50 0.17 g) mp 193-197°. 

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