1. General description and application
Niacin (also called Nicotinic Acid) and Niacinamide (also called Nicotinamide), two compounds of water-soluble vitamin B complex, are active in the metabolism of body. Chemically they are 3-Pyridinecarboxylic acid and 3-Pyridinecarboxamide respectively. Commercially, niacin is obtained from beta -picoline or from quinoline, which are both obtainable from coal tar. Niacinamide, more water soluble, is the amide form of niacin. When an amide molecule attaches itself to niacin, it becomes niacinamide. The B vitamins niacin and niacinamide are known as preventives of pellagra. Niacin is interchangeable in metabolism with its amide, niacinamide. Nicotinamide is hydrolyzed to the acid in the digestive tract of non-ruminants. After absorption in the mucosa, the amide is formed again. In the rumen of ruminants, nicotinamide is converted in a short time to nicotinic acid. Nicotinamide and nicotinic acid are therefore equivalent in action in the case of farm animals. These are key ingredients in animal feed and animal feed premixes as these contribute to numerous metabolic reactions as hydrogen-transferring coenzymes. 2-Chloronicotinic acid is used as an intermediate for agrochemicals, feed additives, pharmaceuticals and animal food enrichments. Niacin acts to reduce plasma cholesterol, as a vasodilator and to treat pellagra. Niacin is used for the prophylaxis. Their derivatives are used for these effects.
It Used as pharmaceutical intermediates for the manufacture of cigarettes mefenamic acid , smoke flufenamic acid ; pesticide intermediates for the manufacture of nicosulfuron , Diflufenican etc.
2. The preparation method
(1) With 3 - methylpyridine as a raw material , the first reaction with hydrogen peroxide, N- oxo-3 - methyl pyridine , and the acid-binding agent the presence of diisopropylamine in a solvent oxychloride was added dropwise phosphorus chloride, ring chlorination agent , to give 2 - chloro-5 - methyl- pyridine and 2 - chloro -3 - methyl pyridine was , crystallization and distillation using separation techniques combination , respectively to give 2 - chloro- - 5 - methylpyridine and 2 - chloro -3 - methyl pyridine. 2 - chloro -3 - methyl pyridine side-chain chlorinated to give 2 - chloro-3 - trichloromethylpyridine further hydrolysis to give 2 - chloro-3 - pyridine chloride or 2 - chloro-3 - pyridine carboxylic acid (2 - chloro- nicotinic acid ) .
(2) In phosphorus oxychloride and phosphorus trichloride mixture leads to chlorine , temperature controlled at about 60 ℃ until there is residual chlorine escape until cooled and nicotinic acid N-oxide was added in portions , heating and mixing liquid at . 100 ~ 105 ℃ reaction 1 ~ 1.5h, until the reaction mixture was then stirred transparent 30min, and the phosphorus oxychloride removed under reduced pressure , the resulting residue was cooled to room temperature, water was finished .
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