Which of the following compounds possesses two configurationally stable enantiomers ?

Options

A. `CH_(3)CH_(2)NHCH_(3)`
B. `CH_(3)CH_(2)CH_(2)overset(CH_(3))overset(|)(NC_(2))H_(5)`
C.
D.

Answer

D

Explanation

Because of its Pyramidal shape and tetraheral geometry an amine of the type `R^(1)R^(2)R^(3)N` is chiral, the unshared pair being considered a fourth different group However it is not possibel to separate the enantiomers because the enantiomers rapidly interconvert having enough kinetic energy at room temperatures by a process called nitrogen inversion
Since the inversion does `no^(+)` involve bond-breaking and subsequent formation the energy of activation is just `6kcalmol^(-1)(25kJmol^(1-))` The `TS` for the inversion is planar the `N` atom being `sp^(2)` hybridized with the lone pair in the `2p` atomic orbital Quaternary ammonium salts (compound4) having four different groups bonded to `N` show optical activity becausse nitrogen inversion is not possible as the unshared pair of electrons on `N` in amines gets bonded in quaternary ammonium salts Consequently the two enantiomers are resolvable .