Hydrochloric Acid → 4-Isocyanato-1,2-dimethoxybenzene

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Reaction Conditions

Reaction Steps

A 3 L, three-necked, round-bottomed flask was equipped with a heating/cooling bath, magnetic stirrer and stir bar, condenser, 500 mL addition funnel, thermocouple, nitrogen inlet, heating bath, vacuum distillation apparatus. To a stirred solution of 3,4-dimethoxyaniline (81.9 g, 535 mmol) in xylenes (1400 mL) was added via the addition funnel, a 4 N solution of hydrogen chloride in 1,4-dioxane (295 mL, 1180 mmol) at ambient temperature. This mixture was stirred at ˜25° C. for 30 minutes, before it was heated to reflux under a slow N2 stream. Neat triphosgene (200.0 g, 674 mmol) was added to the refluxing stirred mixture in portions via the addition funnel over 45 minutes. Upon completion of the addition, the batch was refluxed for another hour. After cooling to ˜60° C., the batch was concentrated under reduced pressure to remove most of the solvent. The oily residue was distilled under high vacuum (b.p. 84-88° C. @ 0.92 mmHg) to afford the title compound as an oil (93.0 g, 97%).

Provenance & Evidence