Dimethylamine → 1-(6-Chloro-3-pyridylmethyl)3,3-dimethyl-2-nitroguanidine

1-(2-chloro-5-pyridylmethyl)-2-methyl-3-nitroisothiourea (1.3 g) was dissolved in ethanol (20 ml) and to the solution was added an aqueous solution (50%) of dimethylamine (0.5 g) at room temperature, followed by one-day stirring at 30° C. The ethanol in the solution was distilled off under reduced pressure and it was purified on a chromatographic column (the eluent was a mixture of methanol and chloroform) so as to obtain the desired 3-(2-chloro-5-pyridylmethyl)-1,1-dimethyl-2-nitroguanidine (1.2 g) having a melting point in the range of from 158° to 160° C.