Question

The decreasing basic character of the following is:
(I) $Ph{O}^{\ominus }$ (II) $C{H}_3{S}^{\ominus }$ (III) $\stackrel{\ominus }{O}H$ (IV) $Me{O}^{\ominus }$

• A. $I>II>III>IV$
• B. $III>IV>II>I$
• C. $IV>III>II>I$
• D. $I>II>IV>III$

Answer 1

Answer: (B)

The increasing acidic character is $PhOH>C{H}_{3}SH>MeOH>H_{2}O$.
Phenols are most acidic (due to resonance stabilization in phenoxide ion) and water is least acidic.
The decreasing basic character is $Ph{O}^{\ominus }<C{H}_3{S}^{\ominus }<Me{O}^{\ominus }<\stackrel{\ominus }{O}H$. As the acidic character increases, the basic character of conjugate base decreases. Since phenols are most acidic, phenoxide ions are least basic.