Preparation method of high purity nicotinamide and nicotinic acid

The invention provides a preparation method of high purity nicotinamide and nicotinic acid. In an ethanol and water system and in the presence of NaOH and MnO2, 3-cyanopyridine hydrolyzes to obtain high content of nicotinamide and nicotinic acid by adjusting the ratio of ethanol and water. When ethanol and water are in the weight ratio of 19:1, 3-cyanopyridine hydrolyzes to obtain is 99.5% of nicotinamide, and the yield is higher than 95%; and when the ethanol and water are in the weight ratio of 1:9, the 3-cyanopyridine hydrolyzes to obtain 99.5% of nicotinic acid, and the yield is more than 95%. The method has the characteristics of mild reaction conditions, high product purity and high yield; and only by adjusting the content of ethanol, high purity nicotinamide and nicotinic acid are obtained. At the same time, the method has less waste and less pollution, and is beneficial for industrialized production.