Nitric Acid → 3,3-dimethyl-6-nitrobenzo[c][1,2]oxaborol-1(3H)-ol

Participants

Reaction Conditions

Reaction Steps

A 22 L round-bottomed-flask equipped with a mechanical stirrer, thermocouple, 2 L dropping funnel and cold bath was charged with 3,3-dimethyl-3H-benzo[c][1,2]oxaborol-1-ol (508 g, 300 g contained, 1.85 mol) and trifluoroacetic acid (1.54 L). The solution was cooled to 5° C. Trifluoroacetic anhydride (722 mL, 5.56 mol, 3.00 eq) was added via dropping funnel over 15 min. After aging at 0-3° C. for 30 min, nitric acid (90% fuming, 108 mL, 2.31 mol, 1.5 eq) was added dropwise over 2 h 50 min keeping the internal temp below 5° C. After aging for 1 h, icewater (10.4 L) was added over 50 min maintaining the reaction temp below 15° C. to provide a slurry. The slurry was aged at 0° C. overnight to provide an orange suspension. The solids were collected on a frit, rinsed with cold water (5 L) and air dried under a stream of air to constant weight (ca 24 h) to provide 364 g of 3,3-dimethyl-6-nitro-3H-benzo[c][1,2]oxaborol-1-ol as a 92.4 wt % pure solid (88%). LC/MS: m/z 208 (M+H)'; 1H NMR (DMSO-d6) δ: 8.52 (d, J=2.2 Hz, 1H), 8.32 (dd, J=8.4, 2.2 Hz, 1H), 7.74 (d, J=8.4 Hz, 1H), 1.50 (s, 6H)

Provenance & Evidence