Advices For Studying Organic Chemistry

Nu − Nu

Nu − Nu

+ CH 3 CH 2 H CH 3 CH 2 + H −

+ H 3 C CH 3 H 3 C + CH 3 −

These are not

leaving groups

6. Protonation of an alcohol with a strong acid turns its poor OH– leaving group
   (strongly basic) into a good leaving group (neutral water molecule).

X− R OH X

H

+ R H

+ 2 O

This reaction take place cause

the leaving group is a weak base.

6.14F SUMMARY: SN 1 VERSUS SN 2

1. Reactions of alkyl halides by an SN1 mechanism are favored by the use of:
   
   
   1. substrates that can form relatively stable carbocations.
   
   
   2. weak nucleophiles.
   
   
   3. highly ionizing solvent.
   
   
   
   


2. Reactions of alkyl halides by an SN2 mechanism are favored by the use of:
   
   
   1. relatively unhindered alkyl halides.
   
   
   2. strong nucleophiles.
   
   
   3. polar aprotic solvents.
   
   
   4. high concentration of nucleophiles.
   
   
   
   


3. The effect of the leaving group is the same in both SN1 and SN2:

R–I > R–Br > R–Cl SN 1 or SN 2