Question

Draw the structure of caffeine. Overall, caffeine is somewhat basic. It contains 4 nitrogen atoms, each of which bears a lone pair of electrons. Indicate which of the 4 nitrogen atoms provide caffeine with its basic properties and explain why. Include an explanation of why the other 3 nitrogen atoms are not basic

Answer 1

Explanation:

In the structure drawn of caffeine we can see that there are 4 nitrogen atoms marked 1 to 4.

• The nitrogen atom marked 1 has $sp^2$ hybridization as its lone pair are involved in resonance with the ring by which doesn't act as a proton acceptor.
• The nitrogen atom marked 2 has $sp^2$ hybridization as its lone pair are pointing outwards and away from the ring due to which its lone pair are not involve in conjugation which makes this nitrogen atom basic and it acts as a proton acceptor in a molecule.
• The nitrogen atom marked 3 and 4 in bigger ring has $sp^2$ hybridization as their lone pairs are involved in conjugation with ring and in resonance stabilization of amide by which they doesn't act as a proton acceptor.