2.4- Dibromo 3-pentanone

Propanone, 1,3-dibromo-l,3-diphenyl- (8,9) (958-79-2) Cyclopentadiene 1,3-Cyclopentadiene (8,9) (542-92-7) CH3CHBrCOCBr(CH3)2 3-Pentanone, 2,4-dibromo-2-methyl-... 

The first synthesis of 4-isoxazolidinones (540) resulted from the reaction of 2,4-dibromo-2,4-dimethyl-3-pentanone with hydroxylamine (81H(16)1855>. 

Reduction of 2-bromo-3-pentanone at mercury affords a mixture of 3-pentanone and l-hydroxy-3-pentanone, whereas electrolysis of Q ,Q -dibromoacetone in the presence of benzoate gives a mixture of products arising from both a carbon-bromine bond cleavage and an Sn2 displacement of bromide by benzoate [94]. In an acetic acid-acetate buffer, branched dibromo ketones, such as 2,4-dibromo-2,4-dimethyl-3-pentanone, are reduced to a-acetoxy ketones however, less highly substituted compounds, such as 4,6-dibromo-5-nonanone, undergo simple cleavage of both carbon-bromine bonds [95]. Other work dealing with the reduction of Q, Q -dibromoketones has been described [96]. 

Caution This reaction should be carried out in an efficient hood. 2,4-Dibromo-3-pentanone is a potent lachrymator and a readily absorbed skin irritant. Contact with the skin produces a sensation of sunburn and should be treated immediately by washing with a soap solution followed by washing with sodium bicarbonate solution. 

A. 2,4-Dibromo-3-pentanone (1). A three-necked, 250-ml. flask is fitted with a stirrer, a dropping funnel, and a condenser protected by a calcium chloride drying tube. Bromine (160 g., 1 mole) is added rapidly to a stirred solution of 45 g. (0.52 mole) of 3-pentanone (Note 1) and 1 ml. of phosphorus tribromide maintained between —10° and 0° with a dry ice-acetone bath in an efficient hood. Toward the end of the reaction very large amounts of hydrogen bromide are evolved, and the rate of addition must be controlled to allow the hood to exhaust the gas. Alternatively, a... 

Dihaloketones. A number of studies of the electroreduction of a,a -dibromoketones have been reportedly directed to obtaining evidence for the the intermediacy of cyclo-propanone-derived intermediates (186). Reduction of 2,4-dibromo-2,4-dimethyl-3-pentanone (185) consumed two Faradays of current and gave a species which is briefly stable at -32 °C. The intermediate (186) could be intercepted by subsequent addition of a protonic trapping agent to the low-temperature catholyte (equation 100). Results have... 

When tellurophene was reacted in benzene with 2,4-dibromo-3-pentanone in the presence of diiron nonacarbonyl in a sealed tube for six days at 40u, three bicyclic addition products and one substitution product were identified by NMR spectroscopy4. 

Morpholinocyclopentene has been used to elaborate bicyclo[3.3.0]octane derivatives through cycloaddition to cyanoallene220- and the reagent produced from 2,4-dibromo-3-pentanone and diiron ennacarbonyl.221 ... 

For example, bromination of 3-pentanone gives mostly 2,2-dibromo-3-pentanone. After one hydrogen is replaced by bromine, the enolate ion is stabilized by both the carbonyl group and the bromine atom. A second bromination takes place faster than the first Notice that the second substitution takes place at the same carbon atom as the first,... 

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