The general procedure for synthesizing pyridine-3-acetic acid hydrochloride from 2-chloropyridine-3-acetic acid is as follows:
1. 50 grams of 2-chloro-3-pyridineacetic acid is prepared as 25% mass fraction of 2-chloro-3-pyridineacetic acid sodium solution.
2. 47 g of 30% sodium hydroxide solution (a small amount of insoluble polymer may be generated during the reaction) is added to the above solution, stirred well and filtered.
3. 20% of nickel ruanne catalyst is added to the filtrate, heated to 90-95°C, and the reaction is carried out by passing hydrogen gas at atmospheric pressure or 1MPa pressure.
4. After completion of the reaction, the catalyst is removed by filtration and the filtrate is adjusted to pH 4 with hydrochloric acid.
5. Activated carbon was added for decolorization and the solvent was subsequently removed to obtain a viscous liquid (containing NaCl crystals).
6. 100 g of anhydrous ethanol was added to the viscous liquid, which was fully dissolved and filtered to obtain an ethanol solution of 3-pyridylacetic acid.
7. Remove the ethanol in the solution (after drying to obtain a viscous liquid, can be appropriate amount of water and then dry again).
8. Add 50 g of water and 35 g of hydrochloric acid and react at 50 °C to form a salt, followed by drying to remove the solvent water to obtain a viscous solid.
9. Cooled to room temperature, washed with 50 g of anhydrous ethanol, filtered, rinsed with a small amount of ethanol solid, drying, to obtain 47.5 g of pyridine-3-acetic acid hydrochloride, purity 99.1%, yield 95.0%.
