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2,4,6-Tribromoaniline can be prepared by treating bromine water with aniline in a solution of acetic acid or dilute hydrochloric acid: [1] By reacting bromine with aniline in water, a white precipitate immediately forms and that is 2,4,6-tribromoaniline
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 ...
The reaction of anthracene with N-methylformanilide, also using phosphorus oxychloride, gives 9-anthracenecarboxaldehyde: N -Methylformanilide and anthracene and phosphorus oxychloride In general, the electron-rich arene ( 3 ) must be much more active than benzene for the reaction to proceed; phenols or anilines are good substrates.
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:
The reaction of enolates, enol ethers, or enol acetates with NBS is the preferred method of α-bromination as it is high-yielding with few side-products. [ 11 ] [ 12 ] Bromination of aromatic derivatives
The reaction mechanism for this reaction has been demonstrated to proceed through steps similar to those known for palladium catalyzed CC coupling reactions. Steps include oxidative addition of the aryl halide to a Pd(0) species, addition of the amine to the oxidative addition complex, deprotonation followed by reductive elimination .
The most commonly employed Sandmeyer reactions are the chlorination, bromination, cyanation, and hydroxylation reactions using CuCl, CuBr, CuCN, and Cu 2 O, respectively. More recently, trifluoromethylation of diazonium salts has been developed and is referred to as a 'Sandmeyer-type' reaction.
An example of the Hell–Volhard–Zelinsky reaction can be seen in the preparation of alanine from propionic acid.In the first step, a combination of bromine and phosphorus tribromide is used in the Hell–Volhard–Zelinsky reaction to prepare 2-bromopropionic acid, [3] which in the second step is converted to a racemic mixture of the amino acid product by ammonolysis.