Synthesis
Stage B: Synthesis of ethyl 5-hydroxynicotinate
1. 2.5 g (18 mmol) of 5-hydroxy-3-pyridinecarboxylic acid prepared in Stage A was dissolved in 50 mL of anhydrous ethanol, and the solution was cooled to 0 °C.
2. 4.4 mL (61 mmol) of thionyl chloride was added slowly dropwise with stirring, taking care to control the rate of dropwise acceleration to avoid violent exotherm.
3. After the dropwise addition, the reaction mixture was heated to reflux and kept for 24 hours.
4. After completion of the reaction, the solvent was removed by evaporation under reduced pressure to obtain the crude product.
5. The crude product was poured into an appropriate amount of ice water, stirred and filtered to collect the solid.
6. 2.5 g (yield: 83%) of ethyl 5-hydroxynicotinate was obtained after drying as a white powder.
Product Characterization:
- Molecular Formula: C8H9NO3
- Melting point: 150 ℃
- 1H NMR (300 MHz, DMSO-d6) δ (ppm): 8.74 (d, J = 1.2 Hz, 1H), 8.60 (d, J = 2.6 Hz, 1H), 8.07 (m, 1H), 4.44 (q, J = 7.1 Hz, 2H), 1.42 (t, J = 7.1 Hz, 3H)
- IR (KBr, cm-1): 3044, 2874, 2677, 1731
References
[1] Patent: WO2006/103120, 2006, A2. Location in patent: Page/Page column 115-116
[2] Patent: CN105418620, 2016, A. Location in patent: Paragraph 0008; 0009
