Hydroxide, Hofmann rearrangement, bromine

The classical and most standard reaction conditions of the Hofmann rearrangement use sodium or potassium hypobromite (or bromine with sodium or potassium hydroxide) under aqueous conditions. 

In the Hofmann rearrangement, when an unsubstituted amide is treated with sodium hydroxide and bromine, the corresponding amine with one fewer carbon atom is produced. The first intermediate is the jV-bromo amide, which then undergoes the three steps of the rearrangement reaction simultaneously. Suggest the pathway for this reaction, and how the final product is achieved. 

Hofmann rearrangement of amides (Hofmann degradation) Treatment of a primary amide with sodium hydroxide and bromine or chlorine gives a primary amine, (p. 919)... 

Hofmann Rearrangement Amides with no substituent on the nitrogen react with solutions of bromine or chlorine in sodium hydroxide to yield amines through loss of their carbonyl carbon by a reaction known as the Hofmann rearrangement or Hofmann degradation-. 

The Hofmann Rearrangement (HR), which is often called the Hofmann Reaction or Hofmaim Degradation but should not be confused with the Hofmann Elimination, describes the multistep transformation of a primary carboxamide 1 to a primary amine 3 via an intermediate isocyanate 2 under the action of bromine and sodium hydroxide. " As will be shown, many variations of this rearrangement are known and widely used today. 

The same isocyanate derivative is also seen in the Hofmann rearrangement (Scheme 10.36). TTiat is, if the carboxylic acid chloride from the 2-methylbutanoic acid is first converted to the corresponding amide by reaction with ammonia (NH3) and the latter treated with bromine (Br2) and sodium hydroxide (i.e.,NaOBr formed from reaction of the two reagents), the corresponding A -bromo compound forms. 

Primary amides can also be turned into amines by oxidation with bromine or chlorine in the presence of sodium hydroxide—in other words, by the Hofmann rearrangement (Section 20-7). Recall that in this transformation the carbonyl group is extruded as carbon dioxide, so the resulting amine bears one carbon less than the starting material. 

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