All aliphatic amines are more basic than ammonia but due to delocalisation of lone pair of electrons of the nitrogen atom on the benzene ring, aniline is a weaker base than ammonia. The basic strength of the substituted anilines, however, depends upon the nature of the substituent whereas electron donating group tend to increase, electron-with drawing groups tend to decrease the basic strength. The base trengthening effect of the electron-donating group and the base weaken effect of the electron withdrawing group is, however, more pronouned at p-than at m-position. However due to ortho effect, o-substituted anilines are weaker bases than anilines regardless of the nature of substituent whether electron-donating or electron withdrawing.
Select the weakest base among the following
A. `C_(6)H_(5)CH_(2)NH_(2)`
B. `C_(6)H_(5)CH_(2)NHCH_(3)`
C. `O_(2)N-CH_(2)NH_(2)`
D. `CH_(3)NHCHO`.
