Nitric Acid → 2,3-Dichloro-6-nitrobenzaldehyde

Participants

Reaction Conditions

Reaction Steps

Concentrated sulphuric acid (450 Kg) was added to 2,3-dichlorobenzaldehyde (59 Kg) and the mixture was heated to 40-44° C. for 2 hours, with stirring, to dissolve all the solids then cooled to 20-25° C. over a period of 95 minutes. Nitric acid (70% w/w, 34.5 Kg) was added to the solution, maintaining the temperature between 16 and 28° C., over a period of 110 minutes. The reaction mixture was stirred for 130 minutes, at between 21-25° C., and then quenched by controlled addition over 225 minutes into 1080 Kg of water (pre-cooled to 0-5° C.), maintaining the temperature between 2-20° C., including a vessel rinse of concentrated sulphuric acid (9.2 Kg). The resulting suspension was stirred for 180 minutes at between 10-14° C. then isolated by filtration and washed with pre-cooled (0-15° C.) water (2×297 Kg). The isolated crude solid (151.3 Kg crude, 51.6 kg active weight) was dissolved in methyl tert-butyl ether (590 L) and washed with water (165 L), 10% w/w sodium carbonate solution (165 L) and then water (1654 Solvent was removed by reduced pressure distillation at 17-20° C. until a volume of 160 L was reached, whereupon heptane (1140 L) was added. The resulting slurry was heated to 60° C. over 54 minutes and stirred at between 60-65° C. for 110 minutes, then cooled to 15-20° C. over 11.5 hours. Material was isolated by filtration and washed with heptane 90 L) then dried in vacuo at 40-45° C. to give 2,3-dichloro-6-nitrobenzaldehyde (21.3 Kg) with 96.3% purity (HPLC) in 29% yield.

Provenance & Evidence