|
The Birch reduction is an organic reaction which is particularly useful in synthetic organic chemistry. The reaction was reported in 1944 by the Australian chemist Arthur Birch (1915–1995) working in the Dyson Perrins Laboratory in the University of Oxford, building on earlier work by Wooster and Godfrey in 1937. It converts aromatic compounds having a benzenoid ring into a product, 1,4-cyclohexadienes, in which two hydrogen atoms have been attached on opposite ends of the molecule. It is the organic reduction of aromatic rings in liquid ammonia with sodium, lithium or potassium and an alcohol, such as ethanol and ''tert''-butanol. This reaction is quite unlike catalytic hydrogenation, which usually reduces the aromatic ring all the way to a cyclohexane. The original reaction reported by Arthur Birch in 1944 utilized sodium and ethanol.〔〔〔 Subsequently A. L. Wilds noted that better yields result with lithium. Also the use of t-butyl alcohol has become common. The reaction is one of the main organic reactions utilized in all types of syntheses. : An example is the reduction of naphthalene: : Several reviews have been published. ==Basic reaction mechanism== A solution of sodium in liquid ammonia consists of the electride salt ()+ e−, associated with the intense blue color of these solutions. The solvated electrons add to the aromatic ring to give a radical anion (the arrows depicting the movement of the single electrons should be 'fish-hook' arrows). The added alcohol supplies a proton to the radical anion and also to the penultimate carbanion; for most substrates ammonia is not acidic enough. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Birch reduction」の詳細全文を読む スポンサード リンク
|