Reactivity of Alkyl helides (Application of I Effect)
Application
of I-Effect
II.
Reactivity of Alkyl halides (based on the stability of carbocation)
Alkyl halides are more reactive than
corresponding alkanes.
Methyl chloride is more reactive
than methane.
Reason:-
CH3δ+—Clδ-
CH3—H
-I effect of Cl
I effect of H is ZERO
Polar bond (Polar compound) Non-polar bond
(Non-polar compound)
More reactive Less
reactive
So,
Methyl chloride is more reactive than methane due to –I effect of –Cl
Special
point:-
More
stable intermediate or product, more will be formed.
A <=================> B
x%
y%
If B is more stable than A ==> y > x
If A is more stable than B ==> x > y
CH3—CH2—Cl
<=========> CH3—C+H2 + Cl-
Reactant-I
Intermediate-I
(CH3)3C—Cl
<=========> (CH3)3C+ + Cl-
Reactant-II
Intermediate-II
(CH3)3C+ is more stable than
CH3—C+H2 So, Intermediate-II is more formed than Intermediate-I
and (CH3)3C—Cl is
more reactive than CH3—CH2—Cl
Special
point:-
Reactivity of reactant is directly proportional to
the stability of intermediate.
Reactivity ∝ Stability of intermediate
*More
stable intermediate, more reactive corresponding reactant.
Reactivity
order of Alkyl halide [SN1 reaction]
a.
CH3—Cl
b. CH3—CH2—Cl
c.
(CH3)2C—Cl d. (CH3)3C—Cl
Their Carbocation and stability order:-
a.
CH3+ < b. CH3—C+H2 <
c. (CH3)2C+ < d. (CH3)3C+
a.
Methyl
carbocation < b. 1’C
< c. 2’ C <
d. 3’C
So reactivity order:-
a.
CH3—Cl
<
b. CH3—CH2—Cl
<
c. (CH3)2C—Cl
<
d. (CH3)3C—Cl
Question:-
Which
of the following easily gives white ppt of AgCl with
silver nitrate?
a.
CH3—Cl
b. CH3—CH2—Cl
c.
(CH3)2C—Cl d. (CH3)3C—Cl
Answer:- (d)
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