Hydrochloric Acid → 2-(3,4-Dichlorobenzyl)-5-methyl-4-oxo-3,4-dihydrothieno(2,3-d)pyrimidine-6-carboxylic acid

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Reaction Steps

A mixture of 2-(3,4-dichlorobenzyl)-5-methyl-4-oxo-3,4-dihydrothieno[2,3-d]pyrimidine-6-carboxylic acid mono sodium salt (2.502 g), 1 mol/L aqueous sodium hydroxide solution (6.4 mL) and water (22.5 mL) was dissolved by stirring with heating. The reaction mixture was allowed to cool under room temperature, neutralized with 1 mol/L hydrochloric acid (12.8 mL), and water (8.3 mL) was added. The mixture was stirred at about 75° C. for 1.5 hr, water (50 mL) was added (solvent amount was set to 100 mL), and the mixture was cooled to about 21° C. The suspension was poured into a G2 glass filter (diameter 3 cm), and the pressure reduction was started at 50 hpa. The time necessary to the increase of pressure by the completion of filtration was 4 minutes 14 seconds. The height of the solid at that time was 2.3 cm (bulk 16.2 cm3). Then, an operation of washing the obtained solid with water (25 mL), followed by reduced pressure filtration at 50 hpa was repeated 3 times to confirm that the filtrate had pH 7. At this point, the total filtration time necessary for increasing the pressure was 10 minutes 2 seconds and the height of the final solid was 1.5 cm (bulk 10.6 cm3).

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