1. Preparation of aniline
2. Preparation of methylamine
Hoffmann Bromamide Degradation Reaction Mechanism
Hoffmann bromamide reaction mechanism can be explained in the following steps –
Step 1: In this step primary amide reacts with sodium hydroxide. Hydroxide ion(anion) of NaOH attacks on a group of primary amides which results in deprotonation of primary amides and forms water and negatively charged primary amide ions.
Step 2: In this step while reacting with primary amide ion, one atom of bromine molecule develops partially positive charge while another atom develops partially negative charge due to negatively charged primary amine. It results in the formation of R-CO-NHBr (bromamide) and elimination of Br– .
Step 3: In this step, another molecule of sodium hydroxide reacts with R-CO-NHBr and another water molecule is eliminated and R-CO-NBr is left behind.
Step 4: In this step, R (alkyl or aryl group) gets detached from bromamide anion as R– which results in OC-NBr. Its rate determines the step.
Step 5:In this step R– attacks on the nitrogen atom of O=C=NBr and isocyanate is formed. Now alkyl or aryl groups are attached directly to nitrogen atoms.
Step 6: In isocyanate, a carbon atom is attached with two highly electronegative elements (oxygen and nitrogen), so it develops a partially positive charge. In this step, isocyanate reacts with water molecules, and the removal of carbon dioxide molecules takes place. Which finally results in the formation of primary amine.
Applications of Hoffmann bromamide degradation reaction
Some of the applications of the mechanism are discussed below-
- It is used to produce primary aromatic and aliphatic amines.
- It is used in the preparation of aniline.
- It is used in the preparation of anthranilic acid and phthalimide.
- 3-Aminopyridine is produced by this reaction from nicotinic acid.
- Hoffmann reaction does not change the symmetrical structure of -phenyl propanamide.
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