Preparation of acetaminophen involves treating an amine with an acid anhydride to form an amide. In this case, p—aminophenol, the amine, is treated with acetic anhydride to nbsp; Synthesis of Acetaminophen. Swirl the flask in an attempt to dissolve the amine nbsp; Synthesis of paracetamol by acetylation — Royal Society of Chemistryacetic anhydride etanoic anhydride and paracetamol.
This application is a continuation of Ser. What is claimed is 1. The method according to claim 1, wherein said aqueous acetic acid solution of p-aminophenol contains from about 7. The method according to claim 1, wherein said aqueous acetic acid solution contains from about 2 to about 25 percent, by weight of acetic acid.
The method according to claim 1, wherein N-acetyl-p-aminophenol is filtered from the acetylation reaction medium and the filtrate is recycled to provide at least a portion of said aqueous acetic acid. The method according to claim 1, whereby the absorbent carbon is granular carbon and the said p-aminophenol solution is contacted by passage through and over said carbon.
The present invention relates to the preparation of N-acetyl-p-aminophenol in pure form from p-aminophenol in a simple and efficient manner.
N-acetyl-p-aminophenol, commonly known as Acetaminophen, is a well known and highly useful pharmaceutical compound. For example, N-acetyl-p-aminophenol is commonly employed as a long term analgesic.
In addition to its many uses in the pharmaceutical field, it is also employed as a stabilizer for various materials, e. In order to qualify for use in the pharmaceutical field and indeed in many non-pharmaceutical applications, it is necessary that the N-acetyl-p-aminophenol meet the National Formulary N.
For pharmaceutical use, it must be white in its crystal form and impart no appreciable color to tablet or elixirs in which it is present as an active ingredient.
Generally, N-acetyl-p-aminophenol has been produced from p-nitrophenol which is reduced with hydrogen to p-aminophenol. The aminophenol is then acetylated to acetyl aminophenol. The acetylation can be accomplished by carrying out the reduction in the presence of acetic anhydride as described in U.
In order to make N-acetyl-p-aminophenol of suitable quality in this manner, the p-nitrophenol must first be extensively purified to free it of p-nitrochlorbenzene from which it is made.
In the involved process p-chloroacetanilide is obtained by reduction of the p-nitrochlorbenzene and acetylation of the resulting p-chloro aniline. This chloro compound cannot be tolerated in pharmaceutical grade acetyl aminophenol because of its suspected harmful effects to various organs of the body.
Because of this possibility that p-nitrophenol may contain harmful impurities, inherent to its method of manufacture, it is desirable to employ a safer starting material and preferably one that is less costly. It is well known that a solution or slurry of p-aminophenol in water can be converted to acetyl aminophenol by addition of acetic anhydride.
The resulting N-acetyl-p-aminophenol is then filtered and washed with water. Although this procedure for making the acetyl aminophenol is easily carried out, it has not been competitive with the nitrophenol procedure because of the high cost of p-aminophenol. Another disadvantage of this procedure is that commercially available p-aminophenol is not sufficiently pure and the resulting N-acetyl-p-aminophenol requires extensive treatment in order to obtain a suitable color.
Most of the material made this way still has too much color when treated in accordance with the teachings of U. A recently developed improved procedure for making p-aminophenol which involves reduction of nitrobenzene with hydrogen is described in U. Also several procedures for purification of the p-aminophenol obtained in accordance with this patent have recently been developed.
Among these recently developed methods are the following:So, the selective acetylation of –NH 2 group of ortho- or para-aminophenol was observed even with two equivalents of Ac 2 O to give the corresponding o- or p-hydroxyacetanilide. This might be due to the more nucleophilicity of –NH 2 group rather than –OH group.
Deactivated . The acetylation of p-aminophenol by various heteropolyacids in acetic anhydride at room tem- on the current findings was 50%(w/w).
In all cases, the perature supported heteropolyacid is less active than that of the non-supported. Research papers on neural network, cover letter for hotel front desk help, acetylation of para-aminophenol coursework. Carbon-based solid acid was prepared by hydrothermal carbonization. • p-Aminophenol (PAP) synthesis was studied over Pt/C and carbon-based solid acid..
PAP selectivity was favored at high acid density of the carbon-based solid acid.
Nov 04, · The aqueous acetic acid solution of p-aminophenol which has been treated with adsorbent carbon is contacted with a sufficient amount of acetic anhydride to effect acetylation of the p-aminophenol contained therein.
Preferably, an amount of acetic anhydride from about to about moles per mole of p-aminophenol is used. Acetaminophen is an over‐the‐counter analgesic that is commonly ingested by dogs and cats.
Adverse effects of acetaminophen intoxication include hepatotoxicity and methemoglobinemia.