JEE Main201910 Jan 2019Morning ShiftChemistryGeneral Organic ChemistryActual
The increasing order of the p K a values of the following compounds is:
Options
- AB < C < A < D
- BD < A < C < B
- CB < C < D < A
- DC < B < A < D
Correct answer
A. B < C < A < D
Step-by-step solution
pKa = - logKa Ka ↑ pKa ↓ & vice versa Acidic character α   Ka   α 1 pKa Acidic character α stability of anion (Conjugate base) Conjugate base are Stability of conjugate base α - M   or   - I α 1 + M   or 1 + I - M is more dominating than - I ( B ) − NO 2 at para so exerts - M or - I & - M > - I So it is highly stable anion in ( C ) - NO 2 at meta exerts only - I effect ( A ) No e - withdrawing or electron releasing group. ( D ) - OCH 3 has + M