It was found that p-toluidine and crotonaldehyde reacted in glacial acetic acid, in the presence of 1 mole of sulfuric acid, without any tendency for resinification, to afford a crystalline precipitate corresponding to the formula of C₁₃H₁₇O₂N⋅H₂SO₄. This substance formed 2, 6-dimethylquinoline in a good yield when heated with ferric chloride in glacial acetic acid. From these results, it was found that 2, 6-dimethylquinoline could be obtained in a good yield directly from p-toluidine and crotonaldehyde under mild conditions. In a similar manner, quinaldine is obtained from aniline and crotonaldehyde.