37% hydrochloric acid (354 g, 3.59 mol) was slowly added to a solution of crude 4-chloro-N-methylpyridine-2-carboxamide (500 g, 2.93 mol) dissolved in acetone (2 kg) under stirring conditions and the temperature of the reaction was controlled not to exceed 40 °C. The reaction mixture was then cooled to about 5 °C and stirred continuously for 1 hour. The product was collected by filtration, washed with acetone (580 g) and subsequently dried under reduced pressure (50 °C, 80 mbar). By this method, 521 g (yield 86% of the theoretical value) of 4-chloro-N-methylpyridine-2-carboxamide hydrochloride was obtained. The melting point of the product was 166-168 °C. 1H NMR (DMSO-d6, 500 MHz) data were as follows: δ= 2.83 (d, J = 4.8 Hz, 3H, NCH3); 3.88 (br.s, HCl/H2O); 7.77 (dd, J = 1.9,5.1 Hz, 1H, 5-H); 8.03 (d, J = 1.6, 1H, 3 -H); 8.63 (d, J = 5.2 Hz, 1H, 6-H); 8.90 (br.s, 1H, NH). Mass spectral analysis (DCI, NH3) showed: m/e = 188 [M + NH4]+, 171 [M + H]+ (M = free base).
