Boron trifluoride etherate → 4-(3,4-Dinitrobenzyl)morpholine

Participants

Reaction Conditions

Reaction Steps

(3,4-Dinitrophenyl)-morpholin-4-yl-methanone (0.750 Kg, 2.67 mol, 1.0 wt) and tetrahydrofuran (7.50 L, 10.0 vol) were charged to a flask under nitrogen and cooled to 0 to 5° C. Borontrifluoride etherate (0.713 L, 5.63 mol, 0.95 vol) was added at 0 to 5° C. and the suspension was stirred at this temperature for 15 to 30 minutes. Sodium borohydride (0.212 Kg, 5.60 mol, 0.282 wt) was added in 6 equal portions over 90 to 120 minutes. (A delayed exotherm was noted 10 to 15 minutes after addition of the first portion. Once this had started and the reaction mixture had been re-cooled, further portions were added at 10 to 15 minute intervals, allowing the reaction to cool between additions). The reaction mixture was stirred at 0 to 5° C. for 30 minutes. Reaction completion was determined by 1H NMR analysis (d6-DMSO). Methanol (6.30 L, 8.4 vol) was added dropwise at 0 to 10° C. to quench the reaction mixture (rapid gas evolution, some foaming). The quenched reaction mixture was stirred at 0 to 10° C. for 25 to 35 minutes then warmed to and stirred at 20 to 30° C. (exotherm, gas/ether evolution on dissolution of solid) until gas evolution had slowed. The mixture was heated to and stirred at 65 to 70° C. for 1 hour. The mixture was cooled to 30 to 40° C. and concentrated under vacuum at 40 to 45° C. to give crude 4-(3,4-dinitro-benzyl)-morpholine (0.702 Kg, 98.4%) as a yellow/orange solid.

Provenance & Evidence