Caffeine
IUPAC name	1,3,7-trimethyl-1H-purine-2,6(3H,7H)-dione
Other names	1,3,7-trimethylxanthine, trimethylxanthine, theine, methyltheobromine
Identifiers
CAS number	[58-08-2]
RTECS number	EV6475000
SMILES	C[n]1cnc2N(C)C(=O)N(C)C(=O)c12
Properties
Molecular formula	C8H10N4O2
Molar mass	194.19 g·mol−1
Appearance	Odorless, white needles or powder
Density	1.2 g·cm−3, solid
Melting point	237 °C (non-equilibrium, superheated)
Boiling point	178 °C (sublimes)
Solubility in water	22 mg·mL−1 (25 °C) 180 mg·mL−1 (80 °C) 670 mg·mL−1 (100 °C)
Hazards
MSDS	External MSDS
Main hazards	May be fatal if inhaled, swallowed or absorbed through the skin.
NFPA 704	1 2 0
Flash point	N/A
LD50	192 mg/kg (rat, oral)[1]
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Caffeine is a bitter white crystalline xanthine alkaloid that acts as a psychoactive stimulant drug and a mild diuretic (speeds up urine production)^[2] in humans and other animals. Caffeine was discovered by a German chemist, Friedrich Ferdinand Runge, in 1819. He coined the term "kaffein", a chemical compound in coffee, which in English became caffeine. ^[3] Caffeine is also called guaranine when found in guarana, mateine when found in mate, and theine when found in tea; all of these names are synonyms for the same chemical compound.

Caffeine is found in varying quantities in the beans, leaves, and fruit of over 60 plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants. It is most commonly consumed by humans in infusions extracted from the beans of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut or from cacao. Other sources include yerba mate, guarana berries, and the Yaupon Holly.

In humans, caffeine is a central nervous system (CNS) stimulant, having the effect of temporarily warding off drowsiness and restoring alertness. Beverages containing caffeine, such as coffee, tea, soft drinks and energy drinks enjoy great popularity. Caffeine is the world's most widely consumed psychoactive substance, but unlike most other psychoactive substances, it is legal and unregulated in nearly all jurisdictions. In North America, 90% of adults consume caffeine daily.^[4] The U.S. Food and Drug Administration lists caffeine as a "Multiple Purpose Generally Recognized as Safe Food Substance".^[5] Recent research, however, suggests that regular caffeine use during pregnancy may increase the risk of miscarriage.^[6]