P-acetylaminophenol

Suspend 11 g. of p-aminophenol in 30 ml. of water contained in a 250 ml. beaker or conical flask and add 12 ml. of acetic anhydride. Stir (or shake) the mixture vigorously and warm on a water bath. The solid dissolves. After 10 minutes, cool, filter the solid acetyl derivative at the pump and wash with a little cold water. Recrystallise from hot water (about 75 ml.) and dry upon filter paper in the air. The yield of p-acetylaminophenol, m.p. 169° (1), is 14 g. 

Place 1 55 g. of clean sodium in a 250 ml. round-bottomed flask equipped with a reflux condenser. Add 40 ml. of absolute alcohol (or rectified spirit). If all the sodium has not disappeared after the vigorous reaction has subsided, warm the flask on a water bath until solution is complete. Cool the mixture and add 10 g. of p-acetylaminophenol. Introduce 15 g. (8 ml.) of ethyl iodide slowly through the condenser and reflux the mixture for 45-60 minutes. Pour 100 ml. of water through the condenser at such a rate that the crystalline product does not separate if crystals do separate, reflux the mixture until they dissolve. Then cool the flask in an ice bath collect the crude phenacetin with suction and wash with a little cold water. Dissolve the crude product in 80 ml. of rectified spirit if the solution is coloured, add 2 g. of decolourising carbon and filter. Treat the clear solution with 125 ml. of hot water and allow to cool. Collect the pure phenacetin at the pump and dry in the air. The yield is 9-5 g., m.p. 137°. 

Synonyms. Paracetamol N-(4-Hydroxyphenyl) acetamide p-Acetamidophenol p-Acetylaminophenol N-Acetyl-p-aminophenol Calpol Tylenol APAP. 4.8.2.S Theory... 

Figure 16.6 Microphotograph of the cross section of a drug and the infrared microscopic spectra recorded from different areas (indicated by the arrows) of the cross section, (a) Starch, (b) acetaminophen (p-acetylaminophenol), (c) gum, and (d) gelatin (spectra have been offset to aid clarity). (Source Reproduced with permission from Smiths Detection 2013.)...

---