5.10- Methenyl-5,6,7,8-tetrahydrofolic acid chloride hydrochloride dihydrate

Methenyl-5,6,7,8-tetrahydrofolic acid, chloride hydrochloride dihydrate... 

Methenyl-5,6,7,8-tetrahydrofolic acid, chloride hydrochloride dihydrate (20 g) was added in one portion to 100 ml water at 60°C followed by N,N-diethylethanolamine (14.9 g) which adjusted the pH to 6. The mixture was maintained at reflux for 5 hours and the pH kept between 5.7 and 6.2 by addition of N,N-diethylethanolamine. The mixture was cooled, synthetic magnesium silicate (15 g) added and slurried, and filtered through celite and diluted with 40 ml SD3A (95% ethanol with 5% methanol). The filtrate was kept at -5°C for 16 hours, aqueous calcium chloride (4.0 g) was added dropwise to the cold filtrate, and the precipitate filtered, washed with SD3A (100 ml) and with ethyl acetate (100 ml) and dried under reduced pressure. 

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