Diphenylmethane (5.00 g, 29.72 mmol, 1.0 eq.) was added to a solution of 48% aq. HBr (80 ml) and glacial acetic acid (21 ml). 1,3,5-trioxane (5.35 g, 59.44 mmol, 2.0 eq.) was then added to the mixture, followed by tetradecyltrimethylammonium bromide (0.16 g, 0.48 mmol, 0.016 eq.). The reaction was stirred at reflux (125°C) overnight (16 h). After this time the solution was cooled to ambient temperature, then to 0°C in an ice-water bath. The dark yellow solid was filtered off and washed with several portions of water. The solid was then dissolved in DCM (150 ml), washed with water (100 ml) before drying the DCM layer over Na₂SO₄. This was filtered and the solvent removed in vacuo leaving a light yellow solid, which was recrystallised from hot DCM leaving the pure product as a white solid. Yield = 2.63 g, 7.43 mmol, 25%.

¹H NMR (400 MHz, 298 K, CDCl₃) 7.32 (4H, d, 3JHH = 8 Hz, Ph), 7.15 (4H, d, 3JHH = 8 Hz, Ph), 4.48 (4H, s, CH₂Br), 3.96 (2H, s, CH₂).

¹³C{¹H} NMR (100 MHz, 298 K, CDCl₃) 141.1 (Ph), 135.7 (Ph), 129.3 (Ph), 129.2 (Ph), 41.3 (CH₂), 33.4 (CH₂Br).