Question

For any value of alkyl group (R), the correct order of basic character of the $1^o,2^o,3^o$ amines and $N{H}_3$ in gaseous phase of non polar solvent is:

• A. $3^o>2^o>N{H}_3>1^o$
• B. $3^o>2^o>1^o>N{H}_3$
• C. $2^o>3^o>N{H}_3>1^o$
• D. $1^o>2^o>3^o>N{H}_3$

Answer 1

The correct option is B $3^o>2^o>1^o>N{H}_3$

In gaseous phase, the basic strength of the amines is based on the number of +I groups present in the compound. Higher the number of +I group, greater will be the basic strength of the compound. We know alkyl groups are +I groups. Hence, tertiary amines are more basic than secondary and they are more basic than primary amines.
So the decreasing order of basic strength of amines in gaseous phase follows the order,
$3^o>2^o>1^o>N{H}_3$
for example: for $R=-C{H}_3$ basicity order is given by $(C{H}_3{)}_{3}N>(C{H}_3{)}_{2}NH>C{H}_{3}N{H}_2>N{H}_3$