p-Toluenesulfonic acid → 2-[1-(2,4,6-Trimethylphenylimino)ethyl]-6-[1-(4-tert-butylphenylimino)ethyl]pyridine

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Reaction Steps

Monoimine (1, 2.8 g, 10 mmol) and 4-tert-butylaniline (1.49 g, 10 mmol) (ex. Aldrich) were dissolved in 100 ml of toluene. To this solution, 4 Å molecular sieves and a small amount of p-toluenesulphonic acid (0.1 mmol) (ex. Aldrich) were added. After standing for 5 days with addition of more 4 Å molecular sieves, the mixture was refluxed for 2 h. After filtration the solvent was removed in vacuo. The residue was washed with methanol and recrystallised from ethanol. Yield 2.4 g (58%) of mixed diimine (2). 1H-NMR (CDCl3) δ 8.42 (d, 1H, Py-Hm), 8.34 (d, 1H, Py-Hm), 7.86 (t, 1H, Py-Hp), 7.38 (d, 2H, ArH), 6.89 (s, 2H, ArH), 6.78 (d, 2H, ArH), 2.42 (s, 3H, Me), 2.29 (s, 3H, Me), 2.22 (s, 3H, Me), 2.00 (s, 6H, Me), 1.34 (s, 9H, But).

Provenance & Evidence