Hydrochloric Acid → Phenol, 4-[2-(4-nitrophenyl)ethenyl]-

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A portion (25.8 g) of the α-p-nitrophenyl-p-acetoxycinnamic acid from A above, ethanol (250 mL) and concentrated hydrochloric acid (250 mL) are added to a reactor equipped with a reflux condenser and stirred under a nitrogen atmosphere. Heating commences and after 27 minutes, a refluxing solution is obtained. Refluxing is continued over the next 13 minutes at which time the temperature has increased to 91° C. and an orange slurry has formed. After an additional 63 minutes, the temperature has increased to 92° C. and at this time, the contents of the reactor are poured into deionized water (800 mL) and the resultant precipitate recovered by filtration. The wet filter cake is sequentially washed with two portions (400 mL) of deionized water and dissolved in stirred ethanol (525 mL) maintained at 82° C. The resultant solution is maintained at 4° C. for 16 hours followed by filtration. The recovered product is dried at 75° C. under a vacuum of 2 mm Hg to a constant weight of 16.1 grams of light orange colored needles. A second crop of crystalline product which is formed is not recovered. Fourier transform infrared spectrophotometric analysis of a potassium chloride pellet of the product reveals the presence of the expected hydroxy group O--H stretching absorbance centered at 3429 cm-1 (broad), conjugated nitro group absorbances at 1523 and 1337 (1317 shoulder) cm-1 (sharp) and the ethylene C--H out-of-plane deformation at 972 cm-1. Differential scanning calorimetry of portions (6.8 and 6.7 mg) of the 4-nitro-4'-hydroxystilbene product using a heating rate of 10° C. per minute from 30° to 250° C. under a stream of nitrogen flowing at 35 cubic centimeters per minute reveals a single sharp melting point endotherm centered at 209.4° C. with an enthalpy of 127.5 joules per gram. High pressure liquid chromatographic analysis of the 4-nitro-4'-hydroxystilbene product using a UV detector set at 254 nm reveals a single sharp peak.

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