reaction of phenol with acetic anhydride

175 Torr (0.23 bar). 0000002253 00000 n generally aspirin is synthesized using acetic anhydride. The procedure of Example 11 was repeated, but employing 30 molar equivalents of anhydrous hydrogen fluoride, a reaction temperature of 20°C, and reaction time of 110 minutes. Activity of the drug on the hypothalamic heat-regulating centre is th… When the reaction is complete the paracetamol is then isolated and purified. The hydrogen fluoride was then vented through a caustic scrubber while simultaneously using a nitrogen purge. Privacy 0000315013 00000 n The embodiment of this invention using acetic acid as the acetylating agent results in a conversion of phenol of at least about 80%, preferably at least about 90%, with a selectivity to 4-hydroxyacetophenone (4-H. Phenol reacts with acetic anhydride in the presence of sodium acetate to produce the ester phenyl acetate: The CH_3COO- group of phenyl acetate, like the -OH group of phenol (Practice Problem 15.8), is an ortho-para director. What are the optimum condition for a nucleophilic substitution reaction involving 4-aminophenol, so that the phenolic OH is only allowed to react keeping the aromatic amino not involved in the reaction. The procedure of Example 16 was repeated, but employing 1.25 molar equivalents of acetic acid and a reaction temperature of 50 ± 2°C. Because, the product determining step involves the attack of the phenolic -OH to the protonated anhydride and is directed by the greater nucleophilicity of phenolic -OH rather than carboxylic -OH. Reaction: Mechanism: Uses: It is an effective antipyretic and analgesic. 5. 175 Torr (0.23 bar), 80 g (4.0 mol) of anhydrous hydrogen fluoride was added, and the mixture was warmed to 75°C and maintained at that temperature for 60 minutes without cooling it a second time to -30°C as described in Example 1. In all instances, the invention results in phenol conversions of at least about 80% and reaction selectivities to 4-hydroxyacetophenone of at least about 70%. The reaction proceeded with 99.6% conversion of phenol and with the indicated selectivities to phenyl acetate (0.0%), 4-hydroxyacetophenone (90.5%), 2-hydroxyacetophenone (7.8%), and 4-acetoxyacetophenone (1.1%). The procedure of Example 16 was repeated, but employing 50 molar equivalents of anhydrous hydrogen fluoride, and 1.1 molar equivalents of acetic acid. Please check your email for instructions on resetting your password. The procedure of Example 11 was repeated, but employing 30 molar equivalents of anhydrous hydrogen fluoride, a reaction temperature of 120°C, and reaction time of 2 minutes. I proceeded one reaction with DMF used as solvent, after completion of reaction i did workup with water and ethyl acetate system. In addition, 4-AAA may also be hydrolyzed to form APAP. How to remove DMF completely after completion of reaction ( DMF used as solvent in reaction)? 19. 0000003591 00000 n If a somewhat larger amount of anhydride is used than one half mole per mole of phenol reactant, an excess of free acid will be produced, while if somewhat less anhydride is used, not all the phenol reactant will be used up in the reacticn, i.e., sane phenol reactant will remain at the end of the reaction. The reaction proceeded with 99.3% conversion of phenol and with the indicated selectivities to 4-hydroxyacetophenone (80.2%), 2-hydroxyacetophenone (7.1%), and 4-acetoxyacetophenone (0.1%). A typical acid anhydride is ethanoic anhydride, (CH 3 CO) 2 O. Hi, I have to reduce the NO2 group to NH2 group in the following reaction. This reaction may be conventionally characterized as a Friedel-Crafts acetylation of phenol with acetic acid as the acetylating agent. 2. The formation of phenyl acetate as the major reaction product could be rationalized as being due to the reactivity of the cyclic anhydrides with acetic acid to form acetic anhydride as well as the greater reactivity of phenol with formed acetic anhydride than with the cyclic anhydride. can you please give  some suggestions how to remove DMF completely. : ", Hydrogen fluoride as a condensing agent. 18. VII. for each hydroxyl group) in the presence of 0.01 molar equivalent of the catalyst in acetonitrile (2 mL), as solvent, was carried out, and the desired acetates were obtained in excellent yields at 50 °C (). The formation of phenyl acetate as the major reaction product could be rationalized as being due to the reactivity of the cyclic anhydrides with acetic acid to form acetic anhydride as well … The reaction proceeded with 83.5% conversion of phenol and with the indicated selectivities of phenyl acetate (76.0%), 4-hydroxyacetophenone (6.1%), 2-hydroxyacetophenone (0.4%), and 4-acetoxyacetophenone (1.9%). Number of times cited according to CrossRef: Reactions of Acids and their Derivatives. 0000002700 00000 n All rights reserved. In accordance with this invention, 4-hydroxyacetophenone (4-HAP) is produced by the Friedel-Crafts acetylation of phenol with acetic acid or acetic anhydride using hydrogen fluoride as catalyst, under certain specified reaction conditions so as to obtain unexpectedly high conversions of phenol and high selectivity to 4-HAP, concurrently. The process of claim 8 wherein about 1.0 to 1.25 moles of acetic acid per mole of phenol are employed. MOTT, GRAHAM NIGEL, Inventor name: What is the role of the anhydrous sodium sulphate in the partition gravimetric method? 4 Under the conditions adopted by these authors, ir is doubtful whether acetic acid actually exists as such, since, in the presente of dehydrating agents, it is known to be converted into aoetic anhydride s of The aqueous phase was extracted with 50 mL of ethyl acetate (2x). Performance & security by Cloudflare, Please complete the security check to access. 0000001305 00000 n