These compounds are very similar and differ only by the presence of methyl groups in two positions of the chemical structure. They are easily oxidized to uric acid and other methyluric acids which are also similar in chemical structure. Diuretic, smooth muscle relaxant, cardiac stimulant, vasodilator. The presence of the other alkaloids in colas and tea may explain why these sometimes have a stronger kick than coffee. Colas, which have lower caffeine contents than coffee are, reportedly, sometimes more active.
Tea seems the strongest for some.
Coffee seems more lasting for mental alertness and offers fewer jitters than the others. Sublimes 178 C. Fast sublimation is obtained at 160-165 C under 1mm press.