Wagner, Dr. Frank Technical Center, Celanese Chemical Company, Corpus Christi, Texas.
An alkaloid, formerly synthesized by methylation of theobromine isolated from cacao, but now recovered from the solvents used in the manufacture of decaffeinated coffee. Chemically, caffeine is 1,3,7-trimethylxanthine, and has the structural formula.
It is widely used in medicine as a stimulant for the central nervous system and as a diuretic. It occurs naturally in tea, coffee, and yerba maté, and small amounts are found in cola nuts and cacao. Caffeine crystallizes into long, white needlelike crystals that slowly lose their water of hydration to give a white solid that melts at 235–237.2°C (455–459.0°F). It sublimes without decomposition at lower temperatures. Caffeine has an intensely bitter taste, though it is neutral to litmus.