CONTRIBUTION TO METHYLATION OF 9-ALKYLXANTHINES

Chromatographic and spectral methods were the tools for investigation of the methylation products of the reaction of 1,8,9-trimethylxanthine with methyl iodide in dimethylformamide in the presence of potassium carbonate. In addition to the expected 1,3,8,9-tetramethylxanthine als o products of consecutive reactions - 1,3,7,8-tetramethylxanthine, 1,7 ,8,9-tetramethylxanthinium betaine, 1,7,8,9-tetramethylxanthinium iodi de, 1,3,7,8,9-pentamethylxanthinium iodide and little amounts of 2-met hoxy-1,8,9-trimethylhypoxanthine and 8-ethyl-1,3,7-trimethylxanthine - were separated and identified.