National Carrier Academy

ARYL HALIDE NUCLEOPHILIC SUBSTITUTION REACTION

ARYL HALIDE NUCLEOPHILIC SUBSTITUTION REACTION ARYL HALIDE NUCLEOPHILIC SUBSTITUTION REACTION #

SN1 SN2 E1 E2 & RELATED QUESTION

SN1 SN2 E1 E2 & RELATED QUESTION SN1 SN2 E1 E2 & RELATED QUESTION

QUESTION RELATED TO HOFMANN

QUESTION RELATED TO HOFMANN QUESTION RELATED TO HOFMANN

APPLICATION OF HOFMAN

APPLICATION OF HOFMAN APPLICATION OF HOFMAN ...

E2 REACTION { ELIMINATION REACTION}

E2 indicates an elimination, bimolecular reaction, where rate = k [B][R-LG].
This implies that the rate determining step involves an interaction between these two species, the base B, and the organic substrate, R-LG

Let's look at how the various components of the reaction influence the reaction pathway:

Effects of R-
Reactivity order : (CH3)3C- (CH3)2CH- CH3CH2- CH3-

In an E2 reaction, the reaction transforms 2 sp3 C atoms into sp2 C atoms. This moves the substituents further apart decreasing any steric interactions. So more highly substituted systems undergo E2 eliminations more rapidly. This is the same reactivity trend as seen in E1 reactions.

-LG
The C-LG bond is broken during the rate determining step, so the rate does depend on the nature of the leaving group.
However, if a leaving group is too good, then an E1 reaction may result.

B
Since the base is involved in the rate determining step, the nature of the base is very important in an E2 reaction.
More reactive bases will favour an E2 reaction.

Stereochemistry
E2 reactions occur most rapidly when the H-C bond and C-LG bonds involved are co-planar, most often at 180o or antiperiplanar. This sets up the s bonds that are broken in the correct alignment to become the p bond.

Selectivity
The outcome of E2 reactions is controlled by the stereochemical requirements described above. Where there is a choice, the more stable alkene will be the major product.

The E2 pathway is most common with:

high concentration of a strong base
poorer leaving groups
R-LG that would not lead to stable carbocations (when the E1 mechanism will occur).
A typical example is the dehydrohalogenation of alkyl halides using KOtBu / tBuOH.

E2 REACTION { ELIMINATION REACTION} E2 REACTION { ELIMINATION REACTION} indicates an elimination, bimolecular reaction, where rate = k [B][R-LG]. Thi...

ELIMINATION REACTION { E1 REACTION}

ELIMINATION REACTION { E1 REACTION} ELIMINATION REACTION { E1 REACTION} REACTION { E1 REACTION}

enantiomers diastereomers & meso compound

enantiomers diastereomers & meso compound enantiomers diastereomers & meso compound /neet

optical activity by element of symmetry and chiral molecule

optical activity by element of symmetry and chiral molecule optical activity by element of symmetry and chiral molecule