How to Compare the Basicities of Nitrogenous Organic Molecules - Part 1

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.

Caffeine is a CNS (central nervous system) stimulant of the methylxanthine class, and is the most consumed psychoactive substance globally used for its eugeroic (promoting wakefulness), ergogenic (enhancing physical performance), or nootropic (enhancing cognition) properties, and for recreational purpose or in social settings in the form of coffee, tea, soft drink, energy drink and so on.

Question:

Arrange the N-atoms of Caffeine in the decreasing order of basicity:



Click to enlarge the image

Solution infographic:



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lp = Lone pair

Is Caffeine eugeroic, ergogenic, nootropic, recreational and/or social substance for you❓ Let Chemaficionado know 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).

(3)    Wikipedia Contributors. Caffeine. Wikipedia. https://en.wikipedia.org/wiki/Caffeine.

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