Advices For Studying Organic Chemistry

3. SN1 reaction is favored over E1 reaction in most unimolecular reactions.
   
   
   1. In general, substitution reactions of tertiary halides do not find wide use as
      synthetic methods.
   
   
   2. Increasing the temperature of the reaction favors reaction by the E1 mechanism
      at the expense of the SN1 mechanism.
   
   
   3. If elimination product is desired, it is more convenient to add a strong base
      and force an E2 reaction to take place.
   
   
   
   

6.20 OVERALL SUMMARY

Table 6.7 Overall Summary of SN1, SN2, E1 and E2 Reactions

CH 3 X

Methyl

RCH 2 X

1°

RR’CHX

2°

RR’R”CX

3°

Bimolecular reactions only SN1/E1 or E2

Gives SN 2

reactions

Gives mainly SN 2

except with a

hindered strong

base [e.g.,

(CH 3 ) 3 CO–] and

then gives mainly

E2

Gives mainly SN 2

with weak bases

(e.g., I–, CN–,

RCO 2 – ) and mainly

E2 with strong

bases (e.g., RO–)

No SN2 reaction.

In solvolysis gives

SN1/E1, and at

lower temperatures

SN1 is favored.

When a strong base

(e.g., RO–) is used

E2 predominates