Dimerization of o-nitro tolueneDimerization of o-nitro toluene
SyntheticPage 729
Published Mar 25, 2014
o-Nitro toluene (550 g, 4.01 mol), cylohexane (2000 mL) and isoamylformate (464 g, 4 mol) are charged to a dry 5 Lt -3 necked flask carrying nitrogen inlet, thermometer pocket and mechanical stirrer at room temperature (whole setup should be in cooling tub to give sufficient cooling for 16-18h). With a slow stream of nitrogen, the reaction mass is cooled to about –2 degree centigrade. At this point, slowly add sodium ethoxide (272 g, 4 mol) in lots (about 10-20 g each lot) slowly over a period of 4 hours keeping the temperature below 3 oC. After complete addition, stir the reaction mixture at the same temperature for additional 8-9 h. T this point, one can observe lots of solid formation in the reaction mixture. Add water ( 2 Lt) and adjust the pH to about 6 and filter the solid. Wash the solid with cyclohexane ( 200-250 mL) to get almost 425-450 g o,o-dinitro bibenzyl. This can be dried at 60-70 oC for 6 h to get about 350-360 g product (64% ). This is almost pure by NMR. If required this can be crystallized by acetone to get light yellow product.