01 What is Caffeine?
A natural stimulant found in coffee, tea, and cacao. Works by blocking adenosine receptors in the brain. Adenosine normally causes drowsiness when it accumulates; caffeine competes for the same receptors without activating them, preventing tiredness.
02 Why It Matters
Caffeine is a methylxanthine - it shares its core structure with the DNA base adenine. Its precise mechanism (competitive antagonist of adenosine A1 and A2A receptors) is why it sharpens alertness without causing direct stimulation.
03 Structure and Bonding
Shape: Planar (xanthine ring system)
Bonds: Multiple C=O, C-N bonds; conjugated ring
Polarity: Weakly polar - The bonding creates a complex charge distribution across the structure.
Decaffeinated coffee still contains 5-30 mg of caffeine - a full cup has 80-100 mg. The caffeine removed is sold to pharmaceutical and soft drink companies.