Advices For Studying Organic Chemistry

Sol O

H

Sol O

H

H CH 2 C+ +

CH 3

CH 3

fast H + C CH^3

CH 3

H 2 C

2-Methylpropene

E1 reaction

iii) The E1 reaction almost always accompany SN1 reactions.

A Mechanism for the E1 Reaction

Reaction:

(CH 3 ) 3 CBr + H 2 O CH 2 =C(CH 3 ) 3 + H 2 O+ + Cl–

Mechanism:
Step 1

H 3 C C

CH 3

CH 3

Cl H 3 C C+

CH 3

CH 3

+ Cl −

slow

H 2 O

This slow step produces the relatively

stable 3o carbocatoin and a chloride ion.

The ions are solvated(and stabilized) by

surrounding water molecules.

Aided by the polar solvent

a chlorine departs with

the electron pair that

bonded it to the carbon.

Step 2

HO

H

HO

H

+ H C +

H

H

C

CH 3

CH 3

β α + H + CC

CH 3

CH 3

H

H

This step produces the

alkene and a hydronium ion

A molecule of water removes one

of the hydrogens from the β carbon

of the carbocation. An electron

pair moves in to form a double bond

between the α and β carbon atoms.

(^)