DIR Return Create A Forum - Home
       ---------------------------------------------------------
       Chemistry:The Central Science
  HTML https://kolathechemist.createaforum.com
       ---------------------------------------------------------
       *****************************************************
   DIR Return to: General Organic Chemistry
       *****************************************************
       #Post#: 44--------------------------------------------------
       Rearrangement of Amides
   DIR By: Michel
       Date: March 18, 2012, 7:59 pm
       ---------------------------------------------------------
       Treating an unsubstituted amide with an aqueous alkaline
       solution of bromine. This reaction is called the Hofmann
       rearrangement. The carbonyl group is lost as CO3(-2)
       eg
       CH3(CH2)4CONH2 + 4OH- +Br2--> CH3(CH2)4NH2+CO3(-2)+2H2O+3Br-
       Give the mechanism of this reaction.
       #Post#: 985--------------------------------------------------
       Re: Rearrangement of Amides
   DIR By: Michel
       Date: October 25, 2012, 10:00 am
       ---------------------------------------------------------
       Any takers?
       #Post#: 988--------------------------------------------------
       Re: Rearrangement of Amides
   DIR By: Potla
       Date: October 25, 2012, 12:41 pm
       ---------------------------------------------------------
       The mechanism is somewhat well-known I guess... it goes through
       an isocyanate intermediate.
       R-CO-NH2 + Br2+ OH-  --> R-CO-NHBr (bromamide) + Br-
       R-CO-NHBr + OH- --> R-CO-N--Br (bromamide anion) + H2O
       R-CO-N--Br --> Br-+ R-CO-N: (nitrene)
       Now this nitrene goes through a C to N R- shift to give the
       isocyanate:
       R-CO-N: --> R-N--C+=O  <--> R-N=C=O (isocyanate)
       R-N=C=O +H2O --> R-NH2 + CO2
       CO2+2OH- --> CO3-2+H2O.
       The reaction is intramolecular, no cross-over products, and the
       configuration of R(the migrating alkyl/aromatic group) is
       retained.
       Hope I wrote it down correctly. :)
       *****************************************************
       Page 1 of 1