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Illustrative is the acetylation of aniline. First aniline is dissolved in water using one equivalent of hydrochloric acid. This solution is subsequently treated, sequentially, with acetic anhydride and aqueous sodium acetate. Aniline attacks acetic anhydride followed by deprotonation of the ammonium ion: Acetate then acts as a leaving group:
Because acetic anhydride is not stable in water, the conversion is conducted under anhydrous conditions. To a decreasing extent, acetic anhydride is also prepared by the reaction of ketene with acetic acid at 45–55 °C and low pressure (0.05–0.2 bar). [8] H 2 C=C=O + CH 3 COOH → (CH 3 CO) 2 O (ΔH = −63 kJ/mol)
Acetanilide can be produced by reacting acetic anhydride with aniline: [7]. C 6 H 5 NH 2 + (CH 3 CO) 2 O → C 6 H 5 NHCOCH 3 + CH 3 COOH. The preparation used to be a traditional experiment in introductory organic chemistry lab classes, [8] but it has now been widely replaced by the preparation of either paracetamol or aspirin, both of which teach the same practical techniques (especially ...
Aniline can react with bromine even in room temperatures in water. Acetyl chloride is added to prevent tribromination. The reaction to form 4-bromoaniline is to protect the amine with acetyl chloride, then hydrolyse back to reform aniline. The largest scale industrial reaction of aniline involves its alkylation with formaldehyde. An idealized ...
Hippuric acid, the benzamide derivative of glycine, cyclizes in the presence of acetic anhydride, condensing to give 2-phenyl-oxazolone. [3] This intermediate also has two acidic protons and reacts with benzaldehyde, acetic anhydride and sodium acetate to a so-called azlactone. This compound on reduction gives access to phenylalanine. [4]
Acetic anhydride. This reagent is common in the laboratory; its use cogenerates acetic acid. [7] [10] Acetyl chloride. This reagent is also common in the laboratory, but its use cogenerates hydrogen chloride, which can be undesirable. [8] Ketene. At one time acetic anhydride was prepared by the reaction of ketene with acetic acid: [11]
Aniline reacts with acyl chlorides or carboxylic anhydrides to give anilides. For example, reaction of aniline with acetyl chloride provides acetanilide ( CH 3 −CO−NH−C 6 H 5 ). At high temperatures, aniline and carboxylic acids react to give anilides.
The following figure shows the reaction mechanism: [2] Reaktionsmechanismus Albright-Goldman-Oxidation. First, dimethyl sulfoxide (1) reacts with acetic anhydride to form a sulfonium ion. It reacts with the primary alcohol in an addition reaction. Furthermore, acetic acid is cleaved, so that intermediate 2 is formed. The latter reacts upon ...