Question

Which of the following does not have an active methylene group?

• A. $C{H}_{3}C{H}_{2}N{O}_2$
• B. $C{H}_{3}COC{H}_{2}COC{H}_3$
• C. $PhCOC{H}_{2}CN$
• D. $C{H}_{3}C{H}_{2}N{H}_2$

Answer 1

The correct option is D $C{H}_{3}C{H}_{2}N{H}_2$

Active methylene group is a one which is surrounded by the electron withdrawing group.

Here $-N{O}_2,-COC{H}_3,and-CN$ groups are electron withdrawing group thus they activate the methylene group.

Here $-N{H}_2$ group and $-C{H}_3$ groups are electron donating group.

Thus they deactivate the methylene group.