“…Crude pyridone salts (1) and (2) (as chloride hydrochlorides; prepared as described previously 3 , were carefully neutralised to pH 5 to 6 with aqueous NaHC03, and then recrystallised and dried before conversion into the 4-chloro-1 -pyridiniopyridinium salts (7) and (8) with POC13. This modified procedure gave consistently higher yields of the salts (7) and (8) than that reported previous1y.J Iminiurn Salts (9) and (lo).-Generally, when equimolar amounts of a chloropyridinium salt [(7) or (8); Y = BF4] and a substituted aniline were heated together under reflux in absolute ethanol for 5 min (Method A), the intermediate iminium salt (9) or (10) was precipitated in high yield on cooling.? In certain cases, however, especially with more basic t The chlorides [(7) or (8) Y = Cl], in contrast, were very hygroscopic and gave unsatisfactory results.…”