JEE Main201912 Jan 2019Morning ShiftChemistryGeneral Organic ChemistryActual
The correct order for acid strength of compounds CH ≡ CH ,   CH 3 - C ≡ CH and CH 2 = CH 2 is as follows:
Options
- ACH 3 - C ≡ CH > CH ≡ CH > CH 2 = CH 2
- BHC ≡ CH > CH 3 - C ≡ CH > CH 2 = CH 2
- CCH ≡ CH > CH 2 = CH 2 > CH 3 - C ≡ CH
- DCH 2 - C ≡ CH > CH 2 = CH 2 > HC ≡ CH
Correct answer
B. HC ≡ CH > CH 3 - C ≡ CH > CH 2 = CH 2
Step-by-step solution
Because acidic character ∝ stability of conjugate base (Anion) (a) CH = C − anion ( − ve  on  C sp ) (b) CH 3 − C ≡ C − ( − ve  on  C sp  and  + I  of  − CH 3 ) (c) CH 2 = C − H ( − ve on  C sp 2 ) Acidic character order CH ≡ C − C sp > CH 3 − C ≡ C − C sp with + I   of  CH 3 > CH 2 = C − C sp 2