[Cl:1]C(Cl)(Cl)C(Cl)=O.[CH3:8][C:9]1[C:14]([CH3:15])=[C:13]([O:16][CH2:17][CH2:18][CH3:19])[CH:12]=[CH:11][N+:10]=1[O-].C(=O)=O.CCOCC>C(OC(C)C)(=O)C>[ClH:1].[Cl:1][CH2:8][C:9]1[C:14]([CH3:15])=[C:13]([O:16][CH2:17][CH2:18][CH3:19])[CH:12]=[CH:11][N:10]=1
A solution of 23 ml of trichloroacetyl chloride in 50 ml of isopropyl acetate is added dropwise during 1 hour to a solution, boiling at reflux under argon, of 13 g of 2,3-dimethyl-4-propoxypyridine 1-oxide in 250 ml of isopropyl acetate. At the beginning the reaction exhibits a very exothermic character. During the addition of the first mol equivalent of trichloroacetyl chloride a vigorous evolution of carbon dioxide is observed. The solution is subsequently stirred under argon for a further 15 minutes at reflux temperature (oil-bath 130° ), cooled to 10° with ice. treated with 100 ml of ether and stirred for 1 hour while cooling with ice. The crystalline precipitate which separates during the entire reaction is filtered off under suction and washed with ice-cold isopropyl acetate and ether. Crystalline reaction product can again be obtained from the mother liquor. The 2-chloromethyl-3-methyl-4-propoxypyridine hydrochloride obtained is processed directly.
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