Synthesis
General procedure for the synthesis of 2-chloroisonicotinic acid from 2-chloro-4-cyanopyridine: 2-chloro-4-cyanopyridine (2 mmol) was dissolved in 5 ml of [bmim]HSO4, and the reaction mixture was heated for 1-3 hours at 60-65 °C. The reaction process was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the reaction mixture was poured into water containing crushed ice and the product precipitated as a precipitate. The precipitate was collected by filtration and dried. High yields (>90%) of 2-chloroisonicotinic acid were obtained in all reactions, and the products were sufficiently pure to require no further purification. The filtrate was concentrated under vacuum, washed twice with diethyl ether and concentrated again under high vacuum. After drying under reduced pressure, about 95% of the ionic liquid was recovered and compared to the original ionic liquid to verify its purity. The recovered ionic liquid showed no significant difference in efficiency of converting nitrile to acid compared to the original ionic liquid and could be reused 5-6 times without significant reduction in activity.
References
[1] Tetrahedron Letters, 2014, vol. 55, # 28, p. 3802 - 3804
[2] Roczniki Chemii, 1955, vol. 29, p. 1019,1025
[3] Chem.Abstr., 1956, p. 12045
