Reactions

[letaps]

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Hey,

How do determine whether a reaction will go E1, E2, SN1 or SN2?

and

What are the differences between the reactions?

Thanks

 

[amm]

Hey,

How do determine whether a reaction will go E1, E2, SN1 or SN2?

and

What are the differences between the reactions?

Thanks

E1 & E2 are elimination reactions. Such reactions "generally" (not always) require higher temperature and basic conditions where the base is not a strong nucleophile; like for example t-BuO-.

Sn1 and Sn2 are substitution reactions. They can take place in all conditions, except when the base is not a strong nucleophile (then elim takes place.)

Reactions in organic chemistry are not definitive. There are very few reactions that only react in one fashion and produce a 100% yield. When you have a molecule with a leaving group mixed with a nucleophile, most likely both elimination and substitution take place. The main question is which results in the major product--and that depends on the conditions (temp and the nucleophilicity of the nucleophile)

Now can you tell whether elimination reactions go E1 or E2, or whether substitution reactions go Sn1 or Sn2? That depends on how substituted the reacting carbon is. More substituted reaction carbon undergo unimolecular reactions (E1 and Sn1).

 

[requeim]

check out the EK orgo book; they have a clear explanation of what type of reaction will most likely occur.

 

[161927]

I try to make this as succinct as possible:


If Carbocation Intermediate: then SN1 or E1. If High Temperature (>75C), then E1.

If bulky nucleophile, then SN1.
If bulky base and carbocation intermediate, then E1.


Else, SN2. If High Temperature (>75C) then E2.