Dichloromethane → 1,4-Naphthoquinone

Participants

Reaction Steps

N-4-Nitrophenyl-N-(3-hexadecyl-1,4-naphthoquinonylmethyl)carbamoyl chloride (6.72 g, 11.3 mmol) was dissolved in 10 ml dry pyridine, using a minimum quantity of dichloromethane to aid in dissolution. The dye (as the methylsulfamoyl form) ##STR8## (4.2 g, 4.72 mmol) was then added and the resulting solution was stirred at room temperature overnight. The mixture was then diluted with ethyl acetate, extracted with 2N hydrochloric acid, dried with anhydrous magnesium sulfate, and filtered. The ethyl acetate was removed in vacuo and the residue was dissolved in 20 percent ethyl acetate in toluene. This solution was passed through a short column of silica gel, eluting first with 20 percent ethyl acetate in toluene to remove some impurities, then with 30 percent ethyl acetate in toluene. This second elutant was concentrated under reduced pressure to yield the crude product (60 percent).

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