Question

The correct order of basic strength in aqueous solution is

• A. $(CH_{3})_{2}NH > \,CH_{3}NH_{2} >\,(CH_{3})_{3}N$
• B. $(CH_{3})_{3}N > \, (CH_{3})_{2}NH >\, CH_{3}NH_{2}$
• C. $CH_{3}NH_{2} >\,(CH_{3})_{3}N > \,(CH_{3})_{2}NH$
• D. $(CH_{3})_{3}N > \, CH_{3}NH_{2} > \, (CH_{3})_{2}NH$

Answer 1

Answer: (A)

In general, the basic strength of amines increases as the number of electron releasing groups ($+I$ showing group like $—CH_{3})$ increases due to more availability of nitrogen to donate its lone pair of electrons. But in aqueous solution, two other factors, i.e., steric effect and solvation effect, also involves due to which tendency of tertiary $(3^{\circ})$ amines to loose their lone pair of electrons i.e., basicity reduces. Thus, the order of basicity, if the electron releasing group in methyl, in aqueous solution is
$(CH_{3})_{2}NH >\, CH_{3}NH_{2}>\, (CH_{3})_{3}N$