Question

Arrange the following in the order of decreasing basic character :
(a) (1) `CH_3NH_2`
(2) `(CH_3)_2NH`
(3) `C_6H_5NH_2`
`NH_3`
(b) (1) `CH_3NH_2`
(2) `(CH_3)_2NH`
(3) `CH_3)_3N`
(4) `C_6H_5NH_2`
( c) (1) `NH_3`
(2) `CH_3NH_2`
(3) `C_6H_5NH_2`
(4) `(C_6H_5)_2NH`
(5) `(C_6H_5)_3 N`
(d) (1) `C_6H_5NH_2`
(2) `p-NO_2C_6H_4NH_2`
(3) `m-NO_2C_6H_4NH_2`
(4) `p-CH_3OC_6H_4NH_2`
( e) (1) `p-`Toluidine
(2) `N,N-`Dimethy1-p-toluidine
(3) `p-`Nitroaniline
(4) Aniline
(f) (1) Methulamine
(2) Dimethylamine
(3) Aniline
(4) `N-`Methylaniline
(g) (1) `RCN`
(2) `RNH_2`
(3) `RN=CHR`
(h) (1) `C_2H_5NH_2`
(2) `(iso-C_3H_7)_3N`
(3) `CH_3CONH_2`
(4) `CH_3 overset (Ө) N HN a^(oplus)`
(i) (1) `overset (Ө) N H_2`
(2) `HC -= C^(Ө)`
(3) `.^(Ө)OH`
(4) `.^(Ө)OR`
(5) `R^(Ө)`
(6) `RCOO^(Ө)`
(j) (1) `H^(Ө)`
(2) `C1^(Ө)`
(3) `NH_2^(Ө)`
(4) `RCOO^(Ө)`
(5) `RO^(Ө)`
.

Answer 1

(a) `2 gt 1 gt 4 gt 3 ((2) 2^@ amine gt (1) 1^@ amine gt (4)` standard `NH_3 gt (3)` aromatic amine)
(b) `2 gt 1 gt 3 gt 4 gt ((2) 2^@ amine gt (1) 1^@ amine gt (3) 3^@ amine gt (4)` aromatic amine)
( c) `2 gt 1 gt 3 gt 4 gt 5 ((2) 1^@ ` amine `gt(1)` Standard `NH_3 gt (3)` Aromatic (amine) `gt (4)` Dipheny1 amine, due to resonance of `L P overline e^, s` on `N` with two benzene rings, basicity decreases `gt (5)` Tripheny1 amine, due resonance of `L P overline e^, s` of `N` with three benzene rings, basicity further decreases, due to nonavailability of `L P overline e^, s` on `N` atom)
(d) `4 gt 1 gt 3 gt 2 [(4) (-OMe)` at `p` (`-I` and `+R`, net `overline e` donating) `gt (1)` Standard, aniline ` gt (3) (-I)` effect of `(-NO_2)` at `m-position gt (1) - I and - R` effects of `(-NO_2)` at `p-position`]
( e)
(f) `2 gt 1 gt 4 gt 3 gt [(2) 2^@` amine ` gt (1) 1^@` amine ` gt (4)` Aromatic amine (with `Me` group on `N, + I` effect of `Me` group) `gt (3)` Standard aniline]
(g) `2 gt 3 gt 1 [(2) 1^@ R - NH_2(sp^3) gt (3) R-N = CH - R(sp^2) gt (1) R - C -= N(sp)` character]
Basicity : `sp^3 gt sp^2` character.
(h) `4 gt 1 gt 2 gt 3 (4)` Anion of `1^@` amine `CH_3 - overset Ӫ underset (ddot) N H, L P overline e^, s` density increases `gt (1) 1^@` amine `gt (2) 3^@` amine `gt (3)` amide.

(i) `5 gt 1 gt 2 gt` Convert conjugate base into acid by adding `H^(oplus)`, find the acidic character and then reverse the order after removing `H^(oplus)` ions that would be the order for basic character.
Acidity : `underset((6))(RCOOH) gt underset ((3))(H_2)O gt underset (4) ROH gt CH -= underset ((2)) CH gt underset ((1)) NH_3 gt underset ((5)) RH`
Basicity : `RCOO^(Ө) lt overset (Ө) OH lt RO^(Ө) lt CH -= C^(Ө) lt overset (Ө) N H_2 lt R^(Ө) (6 lt 3lt 4 lt 2 lt 1 lt 5)`.
(j) `(3 gt 1 gt 5 gt 4 gt 2)` Acidity : `underset ((2))HC1 gt underset ((4)) ROOCH gt underset ((5)) ROH gt underset ((1)) (H_2) gt underset ((3)) NH_3`
Basicity : `C1^(Ө) lt RCOO^(Ө) lt RO^(Ө) lt H^(Ө) lt NH^(Ө) 2 lt 4 lt 5 lt 1 lt 3`
(k)
.