3- Methylpyridine decreased acidity

The pK values of 2-, 3-, and 4-methylpyridine have been determined to be ca. 34, 37, and 32, respectively (Sect. 2, Ref. [1]). Di- and trimethylpyridines are expected to be somewhat less acidic. Since the pK value of ammonia lies within this range, interaction between the heterocyclic compounds and the alkali amides will give rise to certain equilibrium concentrations of the metallated pyridine derivatives. The extent of ionization is expected to decrease in the following order 4-CH3 > 2-CH3 > 3-CH3. As in the metallations of isoprene and a-methylstyrene... 

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