Uses
4,6-Dichloronicotinic acid is an important raw material and intermediate used in organic synthesis, pharmaceuticals, agrochemicals and dyestuff fields.
Synthesis
General procedure for the synthesis of 4,6-dichloronicotinic acid from ethyl 4,6-dichloronicotinate: to a stirred solution of ethyl 4,6-dichloronicotinate (22) (25.95 g, 118 mmol) dissolved in 4:1:1 THF:MeOH:water (600 mL) was added sodium hydroxide solution (40 mL, 6.25 M). After 30 min of reaction, the reaction mixture was acidified to pH 2 with concentrated hydrochloric acid and subsequently diluted with 1:1 EtOAc:Et2O and washed sequentially with water and brine. The organic layer was dried over anhydrous sodium sulfate and concentrated. The resulting off-white solid was purified by concentrating twice from toluene to give the final target product 4,6-dichloronicotinic acid (23) as a white solid (21.73 g, 96% yield).
References
[1] Patent: US2005/49419, 2005, A1. Location in patent: Page/Page column 24
[2] Patent: US2005/54701, 2005, A1
[3] Tetrahedron Letters, 2011, vol. 52, # 4, p. 512 - 514
[4] Patent: WO2014/52365, 2014, A1. Location in patent: Page/Page column 229-230
[5] Patent: US2015/191464, 2015, A1. Location in patent: Paragraph 0611
