Crystals are obtained by heating an aqueous suspension of 2-(3,4-dichlorobenzyl)-5-methyl-4-oxo-3,4-dihydrothieno[2,3-d]p yrimidine-6-carboxylic acid. Novel crystals are obtained by adjusting the heating temperature and/or duration.Se obtienen cristales al calentar una suspensión acuosa del ácido 2-(3, 4-diçlorobencil)-5-metil-4-oxo-3, 4-dihidrotieno[2,3-d]pirim idina-6-carboxílico se obtienen cristales novedosos al ajustar la temperatura de calentamiento y/o su duración.
