Acetone → 4-Difluoromethoxy-8-nitrodibenzo[b,d]furan-1-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

In a 20 L 4 necked RB flask, fitted with a mechanical stirrer, reflux condenser, add 4-difluoro methoxy-8-nitro-1-formyl dibenzo[b,d]furan (1 kg, 3.25 M), acetone (7.2 L) and heat to temp. 70-75° C. under stirring. Add a slurry of potassium permanganate (0.48 kg) in water (3 L) to the reaction mixture at 70-75° C. under stirring and maintain for 1 hr. After 1 hr maintenance, the second lot of potassium permanganate (0.120 kg) in water (400 ml) was added at 70-75° C. under stirring and maintain for 1 hr. After 2 hr maintenance, the third lot of potassium permanganate (0.120 kg) in water (400 ml) was added at 70-75° C. under stirring and maintain for 1 hr. The progress of the reaction was monitored by HPLC. After ascertaining the completion of the reaction, acetone (7.2 L) was added at temp. of 70-75° C. under stirring and maintained for 30 min. The reaction mixture was brought to 25-35° C., filtered. The inorganic salt cake was washed with acetone (2 L) collect and combine all the acetone washings. The acetone MLS were distilled at temp. below 75° C. under vacuum, cool the residue to 25-35° C. and maintain under stirring for 30 min. The precipitated product was filtered, dried and the wet cake was subjected to reflux with a solvent mixture of (5 L acetone and 1.25 L water) and maintained for 3 h. Cool the reaction mass to 10-15° C. maintain for 30 min under stirring, filter the precipitated product, wash the product with water (1 L). The wet cake was subjected to azeotropic removal of water by refluxing with toluene (10 L) After complete removal of water, the reaction mixture was brought to 25-35° C., maintained for 30 min, filtered and dried in vacuum oven below 70° C. till LOD<1%. The dried product appears as cream color, solid, weighs about 840-850 g, yield 80-81%, purity˜95% by HPLC, m.p.>270° C. The IR (KBr) spectrum shows 3100 (C—H str), 1695 (—COOH str), 1100 (C—F str) cm−1. The 1H-NMR spectrum shows δ 9.8 (s, 1H), 8.6 (d, 1H), 8.2 (m, 2H), 7.3 (m, 3H), 7.6 (m, 1H). The CI mass shows m/z 322 (M+) The elemental analysis shows calculated % C, 52.03; % H, 2.18; % N, 4.33. Observed % C, 52.04; % H, 2.03; % N, 4.45%.

Provenance & Evidence