Dimethylformamide → Trans-beta-dimethylamino-4-methyl-2-nitrostyrene

Beteiligte Stoffe

Reaktionsschritte

A 12-l. three-necked flask, equipped with a thermometer, a mechanical stirrer and a 60 cm. vacuum-jacketed silvered column with glass helice packing connected to a total-condensation, variable take-off still head with receiver was charged under nitrogen with 675 g (4.46 moles) of 2-nitro-1,4-dimethylbenzene, 736 g (6.17 moles) of N,N-dimethyl formamide dimethyl acetal and 3.0 l of N,N-dimethylformamide. The mixture was stirred and heated with a heating mantle for 37 hours. The pot temperature was gradually raised from 130° to 144° while the formed methanol was removed by distillation. The fractionating column was replaced by a distilling head with condenser and receiver (cooled in a dry ice-acetone bath). The dimethylformamide was removed by distillation, first at aspirator vacuum and then at high vacuum (water bath 70°), giving a residue of 924 g (100%) of crude product as a dark red viscous oil. This material was poured into a beaker and mixed thoroughly with 640 ml of methyl alcohol. The mixture was stirred in an ice bath until the product crystallized in mass and was then refrigerated overnight. The precipitate was collected by suction filtration, washed with 320 ml of methyl alcohol and dried in vacuo at room temperature (constant weight) to afford 760 g (83%) of product as a free-flowing, dark-red crystalline solid, m.p. 41.5°-43.5° C.

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