Q.
What is the correct increasing order of extent of deprotonation of the following acids in its aqueous solution?
(I) (CH3)2CHCOOH
(II) CH3CH2COOH
(III) Cl2CHCH2COOH
(IV) CH3CCl2COOH
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Organic Chemistry – Some Basic Principles and Techniques
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Solution:
Electron withdrawing group (Cl) increases acidic strength while electron donating group (−CH3) decreases acidic strength. Also magnitude of inductive effect decreases drastically on increasing distance, IV is stronger acid than III.
Two methyl groups (in I) gives greater +I effect than one methyl group (in II), hence I is a weaker acid than II.
Two −Cl from closer position in IV exert greater-I effect than the same from larger distance in III, hence IV is stronger acid than III.