Question

CAffine is one of the most commonly consumed substances found in a number of plants and used as a stimulant. Caffine is an alkaloid. The pKa of caffine is 14.0. For reference, the pKa of water is 15.7 and the pKa for isopropyl alcohol is 17.0.

1. Why does the pKa of caffine make sense based on functional groups in teh molecule. Compare the expected pKa values of the functional groups and discuss the electron withdrawing and induction effects.

2. Based on the pKa values listed above, which is teh strongest acid?

3. What are the most likely atoms in this molecule to act as a nucleophile?

Answer 1

Solution :-

Following image shows the structure of the caffine

solutins for the questions are as follows

1) The pka of the caffine makes sense because in the caffine molecule it contains two carbonyl groups which are electron withdrawing groups therefore they increases the acidity of the protons.

The nitrogens are showing positve inductive effect but the carbonyl groups shows negative inductive effect that is they are electron withdrawing groups.

2) Based on the pka values caffine is the stronger acid because when the pka is smaller then acid is stronger. therefore the stronger acid is the caffine.

3) The N atoms with lone pair of electrons can act as nucleophiles.