Carbon tetrabromide → 1,1-Dibromo-2-{3,5-bis[2-(3,5-di-tert-butylphenyl)vinyl]phenyl}ethene

Participants

Reaction Steps

Triphenylphosphine (3.92 g, 14.96 mmol) was added in one portion to a stirred solution of -3,5-bis[2-(3,5-di-tert-butylphenyl)vinyl]benzaldehyde (1) (2.00 g, 3.74 mmol) and carbon tetrabromide (2.48 g, 7.38 mmol) in dichloromethane (20 mL). Heat was evolved and the mixture stirred at room temperature for 75 min. The resultant orange suspension was washed with water (2×50 mL), dried over anhydrous magnesium sulphate, filtered and the solvent removed to leave an orange-brown residue, which was purified by passing through a plug of silica with dichloromethane—light petroleum (2:3) as eluent. The solvent was removed to give 2-{3,5-bis[2-(3,5-di-tert-butylphenyl)vinyl]phenyl}-1,1-dibromoethene (2) as a white foam (2.45 g, 95%) mp 148-150° C. (Found: C, 69.5; H, 7.3; C40H50Br2 requires C, 69.6; H, 7.3%); νmax(KBr)/cm−1 1595 (C═C) and 958 (C═C—H trans); λmax(CH2Cl2)/nm 306 (log(ε/dm3 mol−1 cm−1)4.85), 317 (4.85) and 329sh (4.73); −δH(400 MHz, CDCl3) 1.40 (36 H, s, t-butyl), 7.14 and 7.24 (4 H, d, J 16, vinyl H) 7.40 (2 H, dd, J 1.5, sp H),7.42(4 H, d, J 1.5, sp H), 7.56 (1 H, s, CHCBr2), 7.60 (2 H, s, cp H) and 7.69 (1 H, s, cp H); m/z (CI+) 692.2 (MH+, 100%), 613.2 (M−79Br, 96%), 611.2 (M−81Br, 90%) and 533.3 (M−279Br, 74%).

Provenance & Evidence