Question

What is the order of basicity of the following compounds in aprotic solvent?

${CH}_3{NH}_2,{\left({CH}_3\right)}_{2}NH,{\left({CH}_3\right)}_{3}N$

• A. ${\left({CH}_3\right)}_{3}N>{\left({CH}_3\right)}_{2}NH>{CH}_3{NH}_2$
• B. ${\left({CH}_3\right)}_{3}N<{\left({CH}_3\right)}_{2}NH<{CH}_3{NH}_2$
• C. ${\left({CH}_3\right)}_{3}N>{CH}_3{NH}_2>{\left({CH}_3\right)}_{2}NH$
• D. None of these

Answer 1

Answer: (A)

${\left({CH}_3\right)}_{3}N>{\left({CH}_3\right)}_{2}NH>{CH}_3{NH}_2$

In aprotic solvents, the decreasing order of basicity of amines is

${\left({CH}_3\right)}_{3}N>{\left({CH}_3\right)}_{2}NH>{CH}_3{NH}_2$

Methyl groups are electron releasing groups and show + I effect. They increase the electron density on nitrogen. As the number of methyl groups increases, the basicity increases.