# ELIMINATION REACTIONS-E1 AND E2

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HI ALL..
HAPPY MORNING...

Today I wanna share with you some useful notes for the chemistry students regarding  Elimination Reactions in organic chemistry(Part-1)

#Elimination reactions in organic chemistry involves removal of two groups/substituents from adjacent carbon atoms to form new Pi bond(π). Practical point of view these reactions are useful for generation of double/Triple bonds in compounds from a saturated starting Material.

Eg: Dehydro halogenation of Alkyl halides to alkenes can be the best example here to explain well.


Elimination Reaction goes  through following events.

  1. removal of a proton
  2. formation of the C-C π bond
  3. leaving group(Halide group) bond breaking
Different mechanisms are possible due to time interval between different events
  1. E2 Reaction:Simultaneous removal of  H+ ,formation of new C=C bond and loss of the halide group(Leaving Group)-Involves One step
  2. E1 reaction:Formation of carbocation by removal of leaving group followed  by removal of  H+  with new C=C bond formation-Involves Two steps
  3. E1cb reaction:Initially carbanion formation by removal of  proton followed by C=C new bond formation with removal of leaving group-Involves Two steps
Factors:   
  1. Nature of  Base :Strong base favours E2 reaction and weak base/acidic medium favours E1     
  2. Nature of leaving group: I > Br > Cl > F  
  3. Nature of solvent : Aprotic solvent like DMF,DMSO favours E2, Protic solvents like Alcohols and acetic acid and water favours E1 reaction
  4.  Alkyl halide order of reactivity for both E1 AND E2 reactions is 30 > 20 >10         


   Thank you all....Soon I will post  PART-2 of Elimination reactions with detailed mechanisams.
   You can post your comments in comment section...All your Suggestions are welcomed..

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