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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Kiliani–Fischer synthesis ： ウィキペディア英語版 Kiliani–Fischer synthesis The Kiliani–Fischer synthesis, named for German chemists Heinrich Kiliani and Hermann Emil Fischer, is a method for synthesizing monosaccharides. It proceeds via synthesis and hydrolysis of a cyanohydrin, thus elongating the carbon chain of an aldose by one carbon atom while preserving stereochemistry on all the previously present chiral carbons. The new chiral carbon is produced with both stereochemistries, so the product of a Kiliani–Fischer synthesis is a mixture of two diastereomeric sugars, called epimers. For example, D-arabinose is converted to a mixture of D-glucose and D-mannose. ==Classic Kiliani–Fischer synthesis== The original version of the Kiliani–Fischer synthesis proceeds through cyanohydrin and aldonic acid lactone intermediates. The first step is to react the starting sugar with aqueous cyanide (typically NaCN); the cyanide undergoes nucleophilic addition to the carbonyl group of the sugar (while sugars tend to exist mainly as cyclic hemiacetal, they are always in chemical equilibrium with their open-chain aldehyde or ketone forms, and in the case of these aldoses it is that aldehyde form that reacts in this synthesis). The cyanohydrin resulting from this addition is heated in water, which hydrolyzes the cyanide into a carboxylic acid group that quickly reacts with itself to form a more stable lactone. Now there are two diastereomeric lactones in the reaction mixture. They are separated (by chromatography, partition into different solvents, or any of the numerous other separation methods) and then the desired lactone is reduced with a sodium amalgam. As illustrated below, D-arabinose is converted to a mixture of D-glucononitrile and D-mannononitrile, which is then converted to D-gluconolactone and D-mannonolactone, separated, and reduced to D-glucose or D-mannose. The chemical yield by this method tends to be around 30%. 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「Kiliani–Fischer synthesis」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.