Which of the following order is correct regarding acidic character of hydrocarbons given below? I. CH ≡ CH CH 2= CH 2 CH 3- CH 3 II. HC ≡ CH CH 3 C ≡ CH CH 3 C ≡ CCH 3

Question

Which of the following order is correct regarding acidic character of hydrocarbons given below? I. CH ≡ CH > CH 2= CH 2> CH 3- CH 3 II. HC ≡ CH > CH 3 C ≡ CH > CH 3 C ≡ CCH 3 (A) Only I (B) Only II (C) Both I and II (D) None of these

Tardigrade Admin · Accepted Answer

Both the orders regarding acidity of hydrocarbon are correct.
I. Acidic strength

\propto

per cent

s

-character and

s

-character is

50%

in alkynes,

33%

in alkanes and

25%

in alkanes.
II. Inductive effect defines acidic strength and polarity of

C - H

bond of alkyne. Groups having

+ I

-effect increases electron density around

C - H

bond, hence polarity decreases and acidic strength of alkyne decreases.

Q. Which of the following order is correct regarding acidic character of hydrocarbons given below? I. CH≡CH>CH2​=CH2​>CH3​−CH3​ II. HC≡CH>CH3​C≡CH>CH3​C≡CCH3​

Only I

Only II

Both I and II

None of these

Q. Which of the following order is correct regarding acidic character of hydrocarbons given below?
I. $C H \equiv C H > C H_{2} = C H_{2} > C H_{3} - C H_{3}$
II. $H C \equiv C H > C H_{3} C \equiv C H > C H_{3} C \equiv CC H_{3}$