MCQ
Considering the basic strength of amines in aqueous solution, which one has the smallest $pK_b$ value ?
- ✓$(CH_3)_2NH$
- B$CH_3NH_2$
- C$(CH_3)_3N$
- D$C_6H_5NH_2$
$\left(\mathrm{CH}_{3}\right)_{2} \bar {N}H>\mathrm{CH}_{3} \bar {N}H_{2}>$$\left(CH_{3}\right)_{3} \bar {N}>\mathrm{C}_{6}\ mathrm{H}_{5} \bar {N} \mathrm{H}_{2}$
As we know $\mathrm{pk}_{\mathrm{b}}=-\log \mathrm{K}_{\mathrm{b}}$
So $ (CH_3) _{2}$ $NH$ will have smallest $pK_{b}$ value. In the case of phenylamine, $N$ is attached to $s p^{2}$ hybridised carbon, hence it has highest $p K_{b}$ and least basic strength.
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Asn - Ser $+\,\underset{(excess)}{\mathop{{{(C{{H}_{3}}CO)}_{2}}O}}\,\xrightarrow{NE{{t}_{3}}}P$