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Organic syntheses vol 58 - Sheppard W.A.

Sheppard W.A., Buchi G.H. Organic syntheses vol 58 - Wiley, 1978. - 123 p.
Download (direct link): organicsynthesesvol581978.pdf
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9. H. Cho and R. G. Harvey, J. Chem. Soc., Perkin Trans I, 836 (1976).
Chemical Abstracts Nomenclature; (Collective Index Number; Registry
Phenanthrene-9,10-oxide (2): Phenanthrene, 9,10-epoxy-9,10-dihydro- (8); Phenanthro[9,10-fc]oxirene, la,9b-dihydro- (9); (585-08-0)
9,10-Phenanthrenediol, 9,10-dihydro-, trans- (1) (8,9); (25061-61-4)
Phenanthrenequinone (8); 9,10-Phenanthrenedione (9); (84-11-7) Lithium aluminum hydride: Aluminate (1-), tetrahydro, lithium
(8), Aluminate (1-), tetrahydro-, lithium, (T-4)- (9); (16853-85-3) N,/V-Dimethylformamide dimethyl acetal: Trimethylamine, 1,1-dimethoxy- (8); Methanamine, 1,1-dimethoxy-A/./V-dimethyl- (9); (4637-24-5)
Dimethylformamide: Formamide, N,/V-dimethyl- (8,9); (68-12-2) Furan, tetrahydro- (8,9); (109-99-9)
2,2'-Biphenyldicarboxaldehyde (8); [1,l'-Biphenyl]-2,2'-dicarbox-aldehyde (9); (1210-05-5)
Phosphorus triamide, hexamethyl- (8,9); (1608-26-0) 9-Phenanthrol, 10-chloro-9,10-dihydro-, acetate (8): 9-Phen-anthrenol, 10-chloro-9,10-dihydro-, acetate (9); (1028-73-5) Trimethylsilyl chloride: Silane, chlorotrimethyl- (8,9); (75-77-4) Benz[a]anthracene (8,9); (56-55-3)
Chrysene (8,9); (218-01-9)
Dibenz[a,hjanthracene (8,9); (53-70-3)
Benzo[c]phenanthrene (8,9); (195-19-7)
Pyrene (8, 9); (129-00-0)
Phenanthrene, 1-methyl- (8,9); (832-69-9)
Benzo[a]pyrene (8,9); (50-32-8)
Benz[a]anthracene, 7,12-dimethyl- (8,9); (57-97-6)
Osmium tetroxide: Osmium oxide (0s04) (8,9); (20816-12-0)
Pyridine-sulfur trioxide: Pyridine, compound with sulfur trioxide
(8), (28322-92-1); Pyridine, compound with sulfur trioxide (1:1)
(9); (26412-87-3)
Dimethyl sulfoxide: Methyl sulfoxide (8); Methane, sulfinylbis-
(9); (67-68-5)
Q î
A. CH3CH2CCH2CH3 + 2Br2 PBr^^y,t), CH3CHBrCCHBrCH3
B 1 + Q 1 -CH3Cn!50“ ' +ØÂÃ
Submitted by M. R. Ashcroft and H. M. R. Hoffmann1 Checked by D. M. Lokensgard and O. L. Chapman
1. Procedure
Cautionl 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-Dihromo-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
gas trap may be used. Depending on the efficiency of the hood, the addition should take 20-40 minutes. The flask is then evacuated with a water pump to remove dissolved hydrogen bromide, and the reaction mixture is immediately fractionally distilled through a 40-cm. column packed with glass helices (or, more quickly, with a Dufton column)2 under reduced pressure. The dibromoketone 1, which is a mixture of dl- and meso-isomers,33 distills at 67-82° (10 mm.), and 91 g. (72%) of product is collected as a colorless liquid (Note 2).
B. 2<x,4<x-Dimethyl-8-oxabicyclo[3.2.1]oct-6-en-3-one (2). A 1-1., three-necked, round-bottomed flask is fitted with a 100-ml. dropping funnel having a nitrogen inlet tube, a magnetic stirrer, a thermometer, and an efficient double-surface condenser carrying a nitrogen outlet tube connected to a bubbler and is placed on a combined hotplate-magnetic stirring unit in a heat-resistant glass dish to act as a water bath. Dry acetonitrile (200 ml.) (Note 3) is introduced into the flask, and 90 g. (0.6 mole) of dried powdered sodium iodide (Note 4) is added with vigorous stirring under a slow stream of nitrogen. When the stirring bar rotates steadily, 20 g. (0.314 g.-atom) of powdered copper bronze (Note 5) is added, followed by 30 ml. (28 g., 0.4 mole) of freshly-distilled furan (Note 6). The dropping funnel is then charged with 24.4 g. (0.1 mole) of the dibromoketone 1 in 50 ml. of dry acetonitrile, and this solution is rapidly added to the stirred reaction mixture (Note 7). On addition of the dibromoketone 1 to the flask, the temperature rises to 45-50°, and a characteristic oatmeal-colored precipitate forms. After about 2 hours the temperature begins to drop, and the reaction is maintained at 50-60° with the water bath for a total reaction time of 4 hours (Note 8).
The flask is cooled to 0° with crushed ice (Note 9), and 150 ml. of dichloromethane is added with stirring. The reaction mixture is then poured into a 2-1. beaker containing 500 ml. of water and 500 ml. of crushed ice. Material remaining in the flask is rinsed into the beaker with 10ml. of dichloromethane, and the mixture is stirred thoroughly, further salts being precipitated, until the ice just melts. The mixture is then filtered into a cooled filter flask under reduced pressure through a sintered or Buchner funnel and a kieselguhr filter-aid cake (Note 10). The beaker and filter cake are
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