The Properties of the Caffeine Molecule

Probably no other chemical has found its way onto so many T-shirts as caffeine. (Water might be a close second.) Even people who have never touched a chemistry book are familiar with this molecule, primarily because they love to drink caffeinated beverages.

Learn also: The Difference between Molecules and Compounds

Caffeine’s best-known effect is that it is a stimulant. Many people rely on it as their morning’s “go-juice”. Commonly found in coffee, tea, and cola, it is readily available for consumption. Have a bit too much of it, and your heart races, your head throbs, and your nerves run on a hair trigger. It is even possible to overdose on caffeine. For an average adult, a lethal dose is around ten grams of caffeine (according to the MSDS). For children (or smaller adults), this value is less. Thankfully, one or two cups of coffee won’t put you anywhere near that limit. On the other hand, eating the raw powder is a very bad idea.

Caffeine is a white powder (like so many other chemicals). It is water soluble (1 gram in 46 mL, or 21.7 grams per liter), which is why we can drink it so readily. It will dissolve in alcohol too, but mixing a stimulant with a depressant (alcohol) is not recommended from a health perspective. Caffeine will melt at a temperature of 238 Celsius (that’s 460 Fahrenheit for those who refuse to convert).

Caffeine is a mild diuretic, which means that it works to dehydrate your body. (In other terms, it makes you urinate.) It is also slightly acidic in water, though the compound itself tastes bitter.

From an environmental standpoint, caffeine isn’t much of a hazard. It is biodegradable in the environment, so it doesn’t stick around. Thanks to its water soluble nature, it doesn’t accumulate in plants / animals either, as it flushes out of their systems with water. (The fancy term is that it doesn’t bioaccumulate.)

Caffeine’s chemical structure is interesting, being a double ring with a high degree of conjugation (alternating single and double bonds). The molecule is mostly flat, but not perfectly so, since the conjugated system does not quite make it all the way around the rings. In structure, it is closely related to guanine and adenine – two of the bases found in DNA. (These compounds are all known as purines.) Caffeine is more highly substituted than either of the bases, however, so don’t worry, it won’t end up in your genetic code, no matter how much of it you drink.

>>MSDS found at: