Ex.1 Compare the acidic strength
Sol. Acidic strength ∝ stability of the anion formed (conjugate base)
As we know I-> Br->Cl-> F
⇒H I >HBr>HCl> HF
Ex.2 Compare the Acidic strength of the following
Sol. Anion formed from there acids are
Ex.3 Compare the acidic strength of the following compounds
CH4, NH3, H2O, HF
Sol. The conjugate base of the given acid is as follows
We have already proved that
⇒ HF > H2O > NH3>CH4 (acidic strength)
Ex.4. Compare the stability of the following carbanion.
Sol. b > c > b > a
* +M or –M is not distance dependent
Ex.5 Compare the stability of the following carbocation
Sol. a > b > c > d
Ex.6 Compare the stability of the following carbocation.
Sol. + M (OH) > + M (OCH3)
b > c > d > a
Ex.7 Compare the stability of the following carbocation
Sol. c > a > b
Ex.8 Compare order of dehydration of the following alcohols:
- C – C – C – OH
Sol. After formation of carbocation
Since 3o Carbocation is most stable therefore it will show greatest tendency to lose water as after lose of water it comes in stable form so the order of dehydration is a > b > c.
Acids and Bases
Ex.9 Compare the acidic strength of the following acids.
- C – C – C – COOH
- C = C – C – COOH
- C ≡ C – C – COOH
Sol. The acid whose conjugate base is most stable will be more acidic.
After forming conjugate base from the above acids.
It is clear that sp hybridized carbon being most electronegative will decrease e- density from O most effectively making the conjugate base most stable.
c > b > a (acidic strength)
Sol. CHF3> CHCl3
If we consider the –I effect of F and Cl But this effect will not be considered here
After the removal of proton
Vacant d-orbital available where C will coordinate its electron) (Pπ – dπbonding)
⇒ a <b (acidic strength)
- CHBr3 (pπ – dπ bonding in Br is not as much as affective as in Cl due to large size of Br)
Sol. CHCl3> CHBr3> CHF3
Ex.12 Compare the acidic strength of the following
More effective Resonance
b > a > c
* Negative charge on O is more
Stable than Negative charge on N as O is more electronegative than N.
* Pπ – Dπ Resonance < Actual Resonance
Ex.13 Compare the acidic strength of the following
- CH ≡CH
- CH2 = CH2
- CH3 – CH3
(Stability of the conjugate base)
a > b > c(acidic strength)
Ex.14 Compare the acidic strength of the following:
- CH3 – CH2 – CH2 – COOH
Sol. d > c > b > a
Ex.15 Compare the acidic strength of the following:
Sol. Conjugate base is in a stability order
Ex.1 6 Compare the acidic strength of the following compound
Sol After forming conjugate base of the above
c > d > b > a
Ex.17 Compare the reactivity of the following compounds with 1 mole of AgNO3
Sol. After removing Cl-
(Positive charge is not on resonance Least stable)
(Most stable as L.P. of Cl will be coordinated to positive charge completing the octet of each atom and making the corbocation most stable)
Extent of positive charge decreases stability increases
Ex.18 Compare the acidic strength
Sol. After making conjugate base
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