Frank George Pope, 1911 Encyclopædia Britannica (1911)
“ Uric acid takes up six hydrogen atoms per molecule and gives purone, C5H8N4O2, and it is apparently the oxygen atom attached to the carbon atom number 6 which is replaced by hydrogen, since when purone is heated with baryta, two molecules of carbon dioxide are liberated for one of purone. Consequently purone must contain two urea residues, which necessitates the presence of the >CO groups in positions 2 and 8. ”
Frank George Pope, 1911 Encyclopædia Britannica (1911)
“ Hypocaffeine on hydrolysis loses carbon dioxide and gives caffolin, C5H9N3O2, which on oxidation with alkaline potassium ferricyanide yields mono methyl urea and methyl oxamic acid, whilst if oxidized by alkaline potassium permanganate it yields dimethyl oxamide. ”
Frank George Pope, 1911 Encyclopædia Britannica (1911)
“ This substance with phosphorus oxychloride yields 3-7-dimethyl-6-amino-2-oxy-8-chlorpurin, which on reduction with hydriodic acid leads to 3-7-dimethyl-6-amino-2-oxypurin, from which theobromine is obtained by the action of nitrous acid. It is also obtained by W. Traube's method (Ber., 1900, 33, p. 3047) from cyanacetyl methyl urea, which gives 3-methyl-4-5-diamino-2~6-dioxypyrimidine, whose formyl derivative yields 3-methylxanthine, from which theobromine is obtained by methylation. ”
