格氏反应操作规程
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格氏反应
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A stirred mixture of magnesium turnings (23.6 g, 0.98 mol) and Et2O (200 mL) under nitrogen is treated with a crystal of iodine and about 5percent of a solution of bromoethane (56.3 ml, 0.75 mol) in Et2O (375 mL). When the reaction starts, the remainder of the bromoethane solution is added, dropwise at a rate sufficient to maintain a gentle reflux. After the addition, stirring is continued for 1 hour. To this solution of ethylmagnesium bromide was slowly added a solution of
4-cyanopyridine (39 g, 0.375 mol) in Et2O (750 ml). The reaction mixture was warmed at reflux for 12 hours, treated with concentrated H2SO4 (125 ml)/H2O (125 ml), and then washed three times with Et2O (250 ml). The aqueous portion was made basic (PH 9) with 15percent NaOH solution and extracted five times with 250 ml portions of Et2O. The combined Et2O extracts were dried (MgSO4), and the solvent was removed under reduced pressure to afford a brown oil (48.4 g, 95percent).