Para-aminophenol

Nitro benzene C6H5NO, Production of aniline, para-aminophenol, and dyes... 

N-substituted phenylhydroxylamine derivatives, e.g. N-acetyl and N-sulphonic acid, also form the para-aminophenol", but more bulky groups prevent reaction, it is thought by steric hindrance to the approach of the hydronium ion. -substituted phenylhydroxylamines, on the other hand form only the ortho product, it is thought via an intramolecular rearrangement, e.g. 

Tylenol paracetamol N-acetyl-para-aminophenol para-acetyl-amino-phenol... 

In addition to their beneficial effects, some medications may actually cause cellular injury and disease. An example of this phenomenon involves nonsteroidal anti-inflammatory drugs (NSAIDS). These drugs include aspirin (a derivative of salicylic acid), ibuprofen (arylpropionic acid, Advil ), and acetaminophen (para-aminophenol derivative, Tylenol ). Because of their beneficial pharmacological effects, consumption of these agents has increased significantly in recent years. NSAIDS have the ability to treat fever, pain, acute inflammation, and chronic inflammatory diseases such as arthritis. They are also used prophylactically to prevent heart disease, stroke, and colon cancer. 

The decomposition of aryl azides in aqueous acid was known to produce para-aminophenols even before Bamberger began his work on the rearrangement of N-arylhydroxylamines. Bamberger recognized that N-arylhydroxyl-amines and aryl azides produced identical product mixtures when decomposed under the same conditions in aqueous acid, and he proposed a... 

When pentafluororutrobenzene reacts with ortho- or para-aminophenol in dimethylformamide solution containing sodium hydroxide, the 4-fluonne is replaced. Either the amino or the hydroxyl function of the aminophenol can act as the nucleophile depending on the reaction conditions [67] (equation 35)... 

Another major group of epoxy monomers derived from epichlorohydrin is that comprising monomers synthesized with an aromatic amine, such as aniline (DGA), para-aminophenol (TGpAP) and methylene dianiline (TGMDA) - (Table 2.1 e, f, and g). The reaction of epichlorohydrin with an alcohol is more difficult. Liquid monomers based on butanediol, neo-pentylglycol, and polypropylene oxide (molar mass in the range of 500 g mol-1), are the most common. 

Formulas Monomethyl para-aminophenol sulfate para-Methylaminophenyl sulfate. 

Formulas 1,2-Benzenediamine, ortho-Diaminobenzene, para-aminophenol hydrochloride. Appearance White to brownish-yellow crystals. 

Which reagent is best can often only be determined by experimentation—commercially, paracetamol is made from para-aminophenol and acetic anhydride largely because the by-product, acetic acid, is easier to handle than HC1. In a retrosynthetic analysis, we don t really want to be bothered by this sort of decision, which is best made later, so it s useful to have a single way of representing the key attributes of alternative reagents. We can depict both anhydride and acyl chloride in this scheme as an idealized reagent —an electrophilic acetyl group MeCO+. 

The chemistry associated with the oxidation of primary intermediates is now reasonably well known. For para-phenylenediamine and para-aminophenol, this involves the process outlined in Fig. 13.40. It can be seen that dye formation is a two-step process involving oxidation and self-coupling. 

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... 

Figure 29.7. Urinary excretion of proximal tubular enzymes following para-aminophenol (PAP) administration to female Sprague-Dawley rats. Rats received PAP (300mg/kgip) and urine was collected for 24 hr following treatment. Urine was assayed for activities of y-glutamyl transpeptidase (GGTP, O), trehalase (TRE, ), and A-acetyl-P-glucosaminidase (NAG, ). Data are expressed as a percentage of enzyme excretion in rats treated with saline. Each data point represents the mean standard error of at least four determinations. GGTP and TRE are enzymes located primarily on the brush border of proximal tubule cells, and NAG is an intracellular enzyme.

Figure 29.8. Kidney tissue from a rat treated with para-aminophenol (300mg/kgip). Tissue was stained with hematoxylin and eosin and was subjected to terminal deoxynucleotidyl transferase-diaminobenzidine (TUNEL) staining to reveal DNA strand breaks. Darker gray areas represent tubules that stain positive for DNA strand breaks. Final magnification was lOOx (left panel) and 360x (right panel).

Cloquinate [ban, inn] is a chloroquine derivative with AMOEBiciDAL properties. Clinically, it can be used as an ANTlMALARiAL prophyaxis and treatment, cloracetadol [inn] is one of the para-aminophenol series, a weak cyclooxygenase inhibitor with NSAID ANALGESIC, ANTIINFLAMMATORY and ANTIPYRETIC activity. 

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