Description
2,3-Lutidine belongs to the pyridine group of derivatives and is a commercially available organic reagent used as an intermediate in organic synthesis and as an acid-binding agent. It is also used as a food additive for flavouring purposes.
Purification Methods
Steam distil it from a solution containing about 1.2 equivalents of 20% H2SO4, until ca 10% of the base has been carried over with the non-basic impurities. The acidic solution is then made alkaline, and the base is separated, dried over NaOH or BaO, and fractionally distilled. The distilled lutidine is converted to its urea complex by stirring 100g with 40g of urea in 75mL of H2O, cooling to 5o, filtering at the pump, and washing with 75mL of H2O. The complex, dissolved in 300mL of H2O, is steam distilled until the distillate gives no turbidity with a little solid NaOH. The distillate is then treated with excess solid NaOH, and the upper layer is removed: the aqueous layer is then extracted with diethyl ether. The upper layer and the ether extract are combined, dried (K2CO3), and distilled through a short column. Final purification is by fractional crystallisation using partial freezing. The picrate crystallises from EtOH with m 187-188o. [Kyte et al. J Chem Soc 4454 1960, Beilstein 20 H 243, 20 II 159, 20 III/IV 2765, 20/6 V 15.]
