Trifluoroacetic acid → 5,6,7,8-Tetrahydro-2-anilinoacridone

Participants

Reaction Conditions

Reaction Steps

A mixture of 139 ml of absolute ethanol, 25 g of sodium methoxide and 67.5 g of diethyloxalate was prepared in a mechanically stirred 1 liter flask under nitrogen atmosphere. The mixture was cooled to 22° C. Cyclohexanone (41.7 g) was added dropwise, keeping the temperature below 35°. The mixture was stirred for 1/2 hour at room temperature, then 236 ml of Dowtherm® A were added. The alcohol was removed by distillation at 35 mm Hg until the reaction mixture temperature reached 29°. The mixture was hydrolyzed by adding a solution of 24 g of concentrated sulfuric acid, 216 ml of water and 9 g of sodium chloride. An additional 3 g of sodium chloride were added to speed separation of the layers. The layers were separated and the organic layer was washed three times with saturated aqueous sodium chloride. The organic layer was then dehydrated by distillation at 25 mm Hg and 65° for 3/4 hour. A 50 % aqueous solution of sodium hydroxide (0.6 g) was added and the mixture heated at 145° for 2.5 hours to effect decarbonylation. An infrared spectrophotometric analysis of the reaction mixture showed 0.311 mole of 2-cyclohexanonecarboxylate ester. One equivalent (57.20 g) of N-phenyl-p-phenylenediamine and 0.8 ml of trifluoroacetic acid were added. The solution was heated at 85° and 25 mm Hg pressure for 1 hour, then 125° and 25 mm Hg for 1/2 hour to bring about condensation. This solution was then added dropwise to 176 ml of refluxing Dowtherm® A in a mechanically stirred flask with a nitrogen sweep through the flask and a steam heated condenser. The addition was adjusted such that the reaction temperature did not drop below 250° C. Reflux was continued for 1 hour after the addition was complete. The mixture was cooled to 90°-100° and filtered to isolate the product. The filter cake was washed well with methanol and was dried in a vacuum oven to give 66.75 g (54%, corrected for loss of product due to above IR sample) of 1,2,3,4-tetrahydro-7(phenyl)amino-9(10H)acridinone.

Provenance & Evidence