烯烴化合物是含碳碳雙鍵的一類化合物，因其雙鍵的不飽和性，可以發(fā)生多種類型的氧化或者還原反應(yīng)，構(gòu)建出各種其他官能團(tuán)，因而在有機(jī)化學(xué)中占有非常重要的地位，是合成各種化合物的重要中間體。
通過鹵代物消除制備烯烴
鄰位碳上有氫原子的脂肪烴是很容易發(fā)生β消除生成烯烴的，如果用一級堿來消除會伴隨取代反應(yīng)的副產(chǎn)物，這種情況用高位阻的堿能提高消除產(chǎn)率。(P. Veeragu, R. T. Arnold, and E. W. Eigemann, J. Am. Chem. Soc., 86, 3072 (1964); R. A. Bartsch and J. F. Bunnett, J. Am. Chem. Soc., 90, 408 (1968).)
實例一
Amixture of 0.4 g (0.8 mmol) of compound Aand 2 ml of piperidine was heated for 10 h at 110°C. The solvent was distilledoff under reduced pressure, the residue was dissolved in 50 ml of methylenechloride, the solution was washed with water and dried over MgSO4, the solvent was removed, and the residue was crystallized from ethanol to give P 0.28 g.
Reference: Russ.J.Org.Chem, 2012, 48, 957-967.
實例二
DibromideI, 5.0 g (18 mmol), was added to a solution of 0.99 g (43 mmol) of metallic sodium in 70 ml of ethanol. The mixture was heated for 1 h under reflux, the solvent was removed under reduced pressure, and the residue was treated with250 ml of water and extracted with ethyl acetate. The extract was dried overanhydrous Na2SO4, filtered, and evaporated under reduced pressure, and the residue was distilled in a vacuum. Yield 54%, colorless transparent viscous liquid. bp 70-90°C (4 mm).
Reference: Russ.J.Org.Chem, 2013, 49, 1329-1334.
來源：覽博網(wǎng)
