Isovanillin → 2-Bromoisovanillin

Participants

Reaction Steps

To a stirred suspension of isovanillin (10 g, 66 mmol), powdered anhydrous sodium acetate (10.82 g, 0.132 mol) and iron powder (0.3 g, 5.4 mmol) in glacial acetic acid (60 mL) under argon, was added drop-wise over 15 min a solution of Br2 (3.7 mL, 0.0726 mol) in acetic acid (12.5 mL). The reaction temperature rose during the course of addition, and the mixture became viscous. After all the starting material was consumed, as determined by TLC, the mixture was poured onto ice cold water, and the resulting precipitate filtered under vacuum. The precipitate was washed several times with cold water and air-dried. Crystallization from boiling ethanol gave 8 (11.93 g, 79% yield) as a gray powder. Rf=0.10 (1:5 EtOAc/hexanes). M.p. 196-200° C. IR (thin film) 3215, 1662, 1588, 1561, 1491, 1273 cm−1. 1H NMR (300 MHz, CDCl3) δ 10.27 (1H, s), 7.59 (1H, d, J=9 Hz), 6.96 (1H, d, J=9 Hz), 6.02 (1H, bs), 4.00 (3H, s). 13C NMR (75 MHz, CDCl3) δ 56.58, 109.24, 112.84, 113.84, 122.74, 143.25, 151.65, 190.87. HRMS calcd. for C8H8O3Br (MH+) 230.9657. Found 230.9652.

Provenance & Evidence