Aniline (Freshly Distilled, ACS reagent, ≥99.5%, Sigma-Aldrich)
2,5-Hexanedione  (≥98%, Sigma-Aldrich)
p-Toluenesulfonic acid • H₂O ( ACS reagent, ≥98.5%, Sigma-Aldrich)
Toluene (anhydrous, 99.8%, Sigma-Aldrich)
Sodium sulfate (ACS reagent, ≥99.0%, anhydrous, granular, Sigma-Aldrich)
Saturated sodium bicarbonate solution
Saturated sodium chloride solution
 

To a 250 mL one-necked round bottom flask equipped with stir bar was added aniline (2.79 g, 0.030 mol), 2,5-Hexanedione (3.65 g, 0.032 mol), and toluene (75 mL, 0.4 M in aniline). Upon mixing for 5 minutes, p-TsOH (0.114 g, 0.0006 mol) was added all at once. The flask was then equipped with a Dean-Stark trap and reflux condenser. The solution was heated to reflux (≈120 ^oC). for 1 hour^a. After this time the flask was cooled to room temperature and the solution was  transferred to a 500 mL separatory funnel. The organic layer was washed with a saturated sodium bicarbonate solution (2 X 100 mL), deionized water (2 X 100 mL), and finally with brine (2 X 100 mL).  The organic layer was dried with Na₂SO₄ and the solvent was removed by rotary evaporation to afford a greenish solid^b,c (3.69 g, 72%). 

¹H NMR (CDCl₃, 300 MHz) δ ppm 2.03 (s, 3 H) 5.91 (s, 2 H) 7.19-7.22-(m, 2 H) 7.38-7.47 (m, 3 H) 7.37 (d, J=8.80 Hz, 2 H) ¹³C NMR (CDCl₃, 75 MHz) δ ppm 13.12 (CH₃) 105.82 (CH) 127.72 (C) 128.36 (CH) 128.83 (CH) 129.15 (CH)  139.15 (C)