Synthesis Classical methods Classical methods for the production of<unk> . The classical methods for the production of<unk>  involve the acetylation of 4-aminophenol with acetic anhydride as the last step. They differ in how 4-aminophenol is prepared. In one method, nitration of phenol with nitric acid affords 4-nitrophenol, which is reduced to 4-aminophenol by hydrogenation over Raney nickel. In another method, nitrobenzene is reduced electrolytically giving 4-aminophenol directly. Celanese synthesis An alternative industrial synthesis developed at Celanese involves direct acylation of phenol with acetic anhydride in the presence of hydrogen fluoride, conversion of the resulting ketone to a ketoxime with hydroxylamine, followed by the acid-catalyzed Beckmann rearrangement. :Celanese method for the preparation of<unk> . Reactions<unk>  crystals (crystallized from an aqueous solution) under a microscope. 4-Aminophenol may be obtained by the amide hydrolysis of<unk> . This reaction is also used to determine<unk>  in urine samples: After hydrolysis with hydrochloric acid, 4-aminophenol reacts in ammonia solution with a phenol derivate, e.g. salicylic acid, to form an indophenol dye under oxidization by air.
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Meloxicam
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