A 100-mL Erlenmeyer flask was equipped with a stir bar, a thermometer and a dropping funnel, sitting on a magnetic stirrer, surrounded by an ice-salt
bath. Toluene (23.04 g, 27 mL, 0.25 mol) was placed in the flask and a previously chilled mixture of sulfuric acid (35.76 g, 20 mL, 96%, 0.35 mol) and
nitric acid (25 g, 18 mL, 75%, 0.30 mol) was placed in the dropping funnel. With vigorous stirring, the mixed acid solution was dropped in very slowly
(about one drop every 3 seconds), keeping the internal temperature below 20 °C during addition (around 0 °C most of the times). The color faded from
an initial dark red color to an orange yellow color during addition. After complete addition (about 60 minutes), the ice bath was removed and an
air-cooled reflux column was attached to contain splashes. The reaction mixture was stirred vigorously for further 3 hours (2 hours is enough, it
stirred longer because I wasn’t around) without heating or cooling (the reaction is still exothermic on its own). After 3 hours, the reaction
mixture was at room temperature and the color was still brightly yellow. The yellow-colored turbid upper layer, containing the product, was separated
and washed with water (50 mL). |
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) .so what should we do.
