Nitrogen Containing Compounds Question 138
Question: The correct order of basicity of amines in water is : [Pb. CET 2003]
Options:
A) $ {{(CH_3)}_2}NH>{{(CH_3)}_3}N>CH_3NH_2 $
B) $ CH_3NH_2>{{(CH_3)}_2}NH>{{(CH_3)}_3}N $
C) $ {{(CH_3)}_3}N>{{(CH_3)}_2}NH>CH_3NH_2 $
D) $ {{(CH_3)}_3}N>CH_3NH_2>{{(CH_3)}_2}NH $
Show Answer
Answer:
Correct Answer: A
Solution:
Basicity of amines increase with increase in number of $ -CH_3 $ groups (or any group which cause +I effect), due to increase in electron density on N atom. As a rule, the basicity of t-amine should be more than that of s-amine, but actually it is found to be lesser than s-amines. This is due to stearic hinderence of bulkier alkyl groups, which decreases the availability of lone pair of electron on the N atom of the amino group. Hence the correct order of basicity is : $ {{(CH_3)}_2}NH>{{(CH_3)}_3}N>CH_3NH_2 $
BETA
