Question #ed86a

1 Answer
Nov 4, 2017

Here's what I think.

Explanation:

1. #-"CH"_2"CH"_2"CH"_2"C≡CH"#

(a) Inductive effect

#"C"# is more electronegative than #"H"#, so the group would be slightly electron withdrawing.

The effect is slightly enhanced by the #"sp"# hybridized alkyne carbon at #"C4"#. The greater #"s"# character in #"C4"# makes it more electronegative than the #"sp"^3# carbon at #"C3"#.

(b) Resonance effect

Alkyl groups are electron donating via hyperconjugation, which is a form of resonance in which a #"C-H"# σ bond overlaps with a #"p"# orbital on an adjacent carbon atom.

i.stack.imgur.com

2. #-"N"("CH"_3)"COCH"_3#

(a) Inductive effect

The #"N"# atom of the acetamido group is much more electronegative than #"H"#, so the group would be electron withdrawing.

b) Resonance effect

The acetamido group is electron donating because the lone pair on the #"N"# can interact with a #"p"# orbital on an adjacent carbon atom.

#-stackrelcolor(blue)(+)("C")"H-"stackrel(bb(. .))("N")("CH"_3)"COCH"_3 ⟷ -"C""H="stackrelcolor(blue)(+)("N")("CH"_3)"COCH"_3#

3. #-"NHCH"_2"CH"_3#

(a) Inductive effect

The #"N"# atom of the ethylamino group is much more electronegative than #"H"#, so the group would be electron withdrawing.

b) Resonance effect

The ethylamino group is electron donating because the lone pair on the #"N"# can interact with a #"p"# orbital on an adjacent carbon atom.

#-stackrelcolor(blue)(+)("C")"H-"stackrel(bb(. .))("N")"CH"_2"CH"_3 ⟷ -"C""H="stackrelcolor(blue)(+)("N")("CH"_2"CH"_3#

In all cases, the resonance effect outweighs the inductive effect,