Boron tribromide → 2,3,6,7,10,11-Hexahydroxytriphenylene

Participants

Reaction Conditions

Reaction Steps

A portion (1.702 grams, 0.025 methoxy equivalent) of 2,3,6,7,10,11-hexamethoxytriphenylene from A above and benzene (250 milliliters) were added to a glass three necked round bottom reactor and stirred under a nitrogen atmosphere as a slurry. Boron tribromide (10.792 grams, 0.0431 mole) was added to the slurry, then heating commences until a reflux temperature of 82° C. was achieved. After 160 minutes at the 82° C. reflux, the nitrogen blanket was removed from the reactor and a distillation head was added. A vacuum was introduced to effect distillation of the benzene solvent plus any unreacted boron tribromide from the reactor. The resultant dry powder remaining in the reactor was combined with deionized water (400 milliliters), then stirred under a nitrogen atmosphere with heating to 100° C. The resultant slurry was cooled to 80° C., then filtered. The precipitate was recovered and was washed with deionized water (50 milliliters) followed by filtration. The recovered precipitate was dried in a vacuum oven at 25° C. and 1 mm Hg to a constant weight of 1.35 grams of pale gray colored product. High pressure liquid chromatographic analysis reveals a single peak for the 2,3,6,7,10,11-hexahydroxytriphenylene product at 95 area percent (detector at 254 nm), with a single minor coproduct peak present. Differential scanning calorimetry of a portion (9.1 or 12.8 milligrams) of the product using a heating rate of 10° C. per minute, and a range from 30° to 500° C. under a stream of nitrogen flowing at a rate of 35 cubic centimeters per minute reveals a sharp melting point endotherm with a minimum at 398.1° C. and an enthalpy of 27.0 joules per gram. A sharp exothermic rise above the baseline comprises the endpoint of this endotherm and was immediately followed by a sharp endothermic descent below the baseline, then a sharp exotherm with a maximum at 423.4° C. and an enthalpy of 99.0 joules per gram (data averaged from two analysis). Infrared spectrophotometric analysis of a potassium bromide pellet of the product reveals the disappearance of the C--H stretch vibration for the methoxy group at 2831 cm-1, the aromatic ring C--O vibration for the ether linkage at 1264 cm-1 and the aliphatic portion of the C--O vibration for the ether linkage at 1045 cm-1, concurrent with the presence of the O--H stretch vibration for the phenolic hydroxyl group at 3422 (3296 slight shoulder) cm-1, the C--H stretch vibrations for the aromatic ring C=C groups at 1629 (1603 shoulder), 1536 and 1443 cm-1, aromatic ring C--O stretch vibrations at 1277, 1224 and 1178 cm-1, O--H deformation at 1370 cm-1 and the C--H out-of-plane vibration for the aromatic rings at 859 and 793 cm-1.

Provenance & Evidence