Caffeine
Molar mass: 194.19 g/mol · Class: Alkaloid (xanthine)
Elements: carbon, hydrogen, nitrogen, oxygen
Structure
Caffeine is a xanthine alkaloid: fused six- and five-membered rings containing four nitrogens, with three methyl groups attached. Its shape lets it block adenosine receptors in the brain.
Properties
White bitter powder, moderately soluble in hot water
Central nervous system stimulant
Half-life of about 5 hours in adults
Naturally occurs in coffee beans, tea leaves, and cacao
Applications
Coffee, tea, energy drinks, and chocolate
Headache and cold medicines (combined with painkillers)
Sports and alertness products
Excess causes jitters, rapid heartbeat, anxiety, and insomnia; very high doses are dangerous. Children, pregnant people, and those with heart conditions should limit intake: ask a health professional. Energy-drink powders can deliver dangerous doses.
Data source: IUPAC standard atomic weights 2021; molar mass computed from C8H10N4O2