由腈分解酰胺

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腈加水可以剖析为伯酰胺。由于伯酰胺会持续水解为羧酸,一样平常要控制水解的条件。现在有很多办法报道,偶然必要依据底物的特征选择酸性,碱性或中性的水解条件。作为中性的条件,也有文献报道利用镍或钯催化剂的办法。

在酸性条件下与饱和碳相连的氰基,可以在酸中很利便的水解转化为酰胺,并在条件较为猛烈时,很容易进一步水解成酸。但乙烯基或芳基腈的水解条件则要求猛烈得多,一样平常必要强酸条件,并且一样平常不会进一步水解。

在碱性条件下,使用过氧化氢氧化的办法可在室温下短工夫内水解腈为伯酰胺,这是一个较为牢靠的办法。使用NaOH(aq.)-CH2Cl2 相转移催化系统,DMSO-K2CO3 系统,可以用于种种腈水解为伯酰胺。

1、盐酸水解腈为伯酰胺示例(Organic Syntheses, Coll. Vol. 1963, 4, 760)


In a 3-l. three-necked round-bottomed flask equipped with glass joints are placed 200 g. (1.71moles) of benzyl cyanide and 800 ml. of 35% hydrochloric acid. The flask is fitted with a reflux condenser, a thermometer, and an efficient mechanical stirrer. At a bath temperature of about 40° the mixture is stirred vigorously. Within a period of 20–40 minutes the benzyl cyanide goes into solution. During this time, the temperature of the reaction mixture rises about 10° above that of the bath. The homogeneous solution is kept in the bath with, or without, stirring for an additional 20–30 minutes. The warm water in the bath is replaced by tap water at about 15–20°, and the thermometer is replaced by a dropping funnel from which

800 ml. of cold distilled water is added with stirring. After the addition of about 100–150ml., crystals begin to separate. When the total amount of water has been added, the mixture is cooled externally with ice water for about 30 minutes. The cooled mixture is filtered by suction. Crude phenylacetamide remains on the filter and is washed with two 100-ml. portions of water. The crystals are then dried at 50–80°. The yield of crude phenylacetamide is 190–200 g. (82–86%).


2 、浓硫酸水解不饱和腈为伯酰胺示例(Org. Syn., Coll. Vol. 1973,5, 73; 1955,3, 66,88)


To 106 g of 84 % sulfuric acid, was added 50 g of acrylonitrile. After stirring for 30 min at r.t., the resulting mixture was heated to 95 ℃, and stirred for 2 h. After cooling, the solid was collected by suction, and the filter cake was transferred into a beaker. To the ice-cooled solid, was added aq. ammonia with the speed that keep the temperature less than 50℃. The precipitated ammonium sulphate was filtered off, and the filtrate was cooled. The precipitate was collected by filtration, and the filter cake was washed by water, dried in vacuum to give

the desired product.


3、 H2O2-K2CO3-DMSO 系统水解腈为伯酰胺示例(Synthesis 1989, 949)


To a stirred solution of 4-chlorobenzonitrile (1.37 g, 0.01 mol) in DMSO (3 ml), cooled in a ice bath, was added 30% H2O2 (1.2 ml) and K2CO3, the reaction was allowed to warm up to r.t. (strong exothermic effect was observed). After 5 min., distilled water (50 ml) was added, cooling applied, and the product was collected by filtration, yield 85%.


4、NaOH(aq.)-CH2Cl2 相转移催化系统水解腈为伯酰胺(Synthesis, 1980, 243)


To a magnetically stirred dichloromethane solution (1.5 ml) of o-tolunitrile (0.5 g, 4.27 mmol) cooled in an ice bath, are added 30% hydrogen peroxide (2.0 ml), tetrabutylammonium hydrogen sulfate (0.290 g, 0.85 mmol), and a 20% aqueous solution of sodium hydroxide (1.6 ml). The reaction mixture is allowed to warm up to r.t. and maintained under stirring. After 1.6 h, dichloromethane is added, the organic layer is separated, washed with brine, and dried with sodium sulphate. The solvent is removed under reduced pressure to leave a white solid from

which pure o-toluamide is obtained by chromatography on silica gel. Yield 0.485 g (97%).


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