By Hofmann degradation (Hofmann rearrangement / Hofmann bromamide degradation / Hofmann hypobromite degradation)

Hofmann degradation -- also called Hofmann rearrangement, Hofmann bromamide degradation, or Hofmann hypobromite degradation, all names for the same reaction -- is described as a genuinely GOOD laboratory method for converting an amide into a primary amine containing ONE CARBON FEWER than the starting amide. The reaction is carried out simply by warming the amide together with bromine and concentrated aqueous potassium hydroxide solution: R-CO-NH2 + Br2 + 4 KOH (aqueous), heat, gives R-NH2 + 2 KBr + K2CO3 + 2 H2O. Worked with acetamide as the specific example: CH3-CO-NH2 + Br2 + 4 KOH (aqueous), heat, gives CH3-NH2 (methylamine) + 2 KBr + K2CO3 + 2 H2O. Looking at the overall transformation, the net effect of this reaction is the complete removal of the -C(=O)- carbonyl-carbon unit from the amide -- the product primary amine ends up with exactly one carbon atom FEWER than the amide it started from, which is why this whole conversion is explicitly de …