How to Compare the Basicities of Nitrogenous Organic Molecules – Part 2

There exist three definitions in common use of the word ‘base’: Arrhenius bases, Brønsted bases, and Lewis bases.


In the current scenario, we will be using a Lewis base, which is any species that has a filled orbital containing an electron pair which is not involved in bonding but may form a coordinate/dative bond with a Lewis acid to form a Lewis adduct or may accept a proton.

Resonance or delocalization of electrons typically reduces the basicity of the N-atom in an organic compound since basicity means an ability to donate an electron pair according to Lewis.

Question:

Arrange the following compounds in the decreasing order of basicity:



Click/tap to enlarge the image

Solution infographic:



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lp = Lone pair, cA = Conjugate acid, EWG = Electron withdrawing group, EDG = Electron donating group, M effect = Mesomeric effect, I effect = Inductive effect

Bedazzled by basicity❓ Let Chemaficionado know in the comments below or at mychemistryhomework@gmail.com❗

References:

(1)    Wikipedia Contributors. Lewis acids and bases. Wikipedia.‌

(2)    Wikipedia Contributors. Resonance (chemistry). Wikipedia. https://en.wikipedia.org/wiki/Resonance_(chemistry).

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