Theine
in chemistry, formula C8H10N4O2, an organic base, occurring in tea leaves, in Paraguay tea, guarana, and in small quantities in cocoa seeds. It is also formed synthetically from theobromine by union with methyl, yielding methyl-theobromine, or theine. To prepare it from tea the leaves are extracted with hot water, the solution precipitated with lead acetate, and the filtrate freed from lead by sulphydric acid. On evaporation of the solution and allowing it to stand for some time, the theine crystallizes out. Purified by animal charcoal it forms tufts of white silky needles, slightly soluble in cold water and alcohol, melting at 225°, and subliming unchanged at a higher temperature. Tea leaves contain from 2 to 4 per cent. of theine, to which the stimulating effect of tea is partly ascribed. At the present day caffeine is the preferred term.