Nitrobenzene Acetaminophen

Acetaminophen (Paracetamol) N- (4 -Flydroxypheny 1) acetamide Partial hydrogenation of nitrobenzene, A-acetylation... 

The majority of the nitrobenzene is used for the production of aniline with a minor amount being used for the production of acetaminophen. 

In 2000, the aniline production in the United States was about 1.9 billion lb. Almost 98 percent of nitrobenzene is used for the production of aniline. Consequently many nitrobenzene plants are integrated with facilities for aniline production. The hydrogenation of nitrobenzene can be done in either the vapor over a copper-silica catalyst or in liquid phase over platinum-palladium catalyst. One of the smaller uses for nitrobenzene is the production of the pain reliever, acetaminophen. 

It must also be pointed out that the medium employed in the reduction process can play a major role in the outcome of the reaction. A good example is the reduction of nitrobenzene in the presence of acid or alkali. One should expect the reduction to follow the course shown in Fig. 13.48 under normal conditions, however, in acidic media the product obtained is mainly para-aminophenol. In fact, this has long been the key step in the commercial route to acetaminophen,52 which is obtained by /-acetylation of the reduction product. When the reduction is conducted in the presence of alkali and Zn, the nitro compound is converted to a hydrazo compound via azoxy and azo intermediates. The hydrazo compound is important because it can be... 

The most widely used analgesic is Paracetamol, or A-acetyl-p-aminophenol (155), also known as acetaminophen (US), and Tylenol (with codeine), and synthesized from nitrobenzene. Care has to be taken with use hepatoxicity can develop with overdoses. 

Figure 33-1 5 Typical separation by MECC. (a) Some test compounds 1 = methanol, 2 = resorcinol, 3 = phenol, 4 = p-nitroaniline, 5 = nitrobenzene, 6 = toluene, 7 = 2-naphthol, 8 = Sudan III capillary, 50-p.m inside diameter, 500 mm to the detector applied voltage, ca. 15 kV detection UV absorption at 210 nm. (b) Analysis of a cold medicine 1 = acetaminophen, 2 = caffeine, 3 = sulpyrine, 4 = naproxen, 5 = guaiphenesin, 10 = noscapine, 11 = chloropheniramine and tipepidine applied voltage, 20 kV capillary, as in (a) detection UV absorption at 220 nm. (From S. Terabe, Trends Anal. Client., 1989,8, 129.)...

The primary use of nitrobenzene is in the captive production of aniline, with about 97.5% of nitrobenzene production consumed in this process. The major use of aniline is in the manufacture of polyurethanes. Nitrobenzene is also used as a solvent in petroleum refining, in the manufacture of cellulose ethers and acetate, and in Friedel-Crafts reactions to hold the catalyst in solution. It is also used in the synthesis of other organic compounds including acetaminophen, which is an over-the-counter analgesic commonly known as Tylenol . 

Nitrobenzene on being subjected to electrol3dic reduction in the presence of sulphuric acid yields para-aminophenol which on treatment with acetic anhydride and sodium acetate gives rise to the production of acetaminophen (or paracetamol). 

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