Tin tetrachloride → Stannous chloride dihydrate

Temperature

42.5 °C

A solution of 7.131 g of tin (II) chloride dihydrate in 4.7 L of concentrated hydrochloric acid was prepared. Separately, 1.631 g of 2,3-dichloro-6-nitrobenzylamine hydrochloride was dissolved in 9.5 L of concentrated hydrochloric acid. The solution of the amine was added to the tin chloride solution over 1-2 hours to maintain the reaction temperature below 45° C. The mixture was stirred for 2 hours at 40-45° C. in a warm water bath, and cooled in an ice/methanol bath to −5° C. The mixture was filtered, and the isolated solids slurried with 13 L water, 6.5 kg ice, and 6 L methylene chloride. Sodium hydroxide (50% aqueous solution) was added until pH >12, and the organic layer was removed. The aqueous phase was extracted with methylene chloride (2×6 L), and the combined organic layers washed with water (6 L portions) until pH=7-8. The organic layers were dried over magnesium sulfate (500 g) and charcoal (200 g) for 16 hours, and filtered. The filtrate was concentrated to an oil, and crystallized from isopropanol at −20° C. to give 2-amino-5,6-dichlorobenzylamine in 58 to 96% yield.

1. temperatureto maintain the reaction temperature below 45° C
2. temperaturecooled in an ice/methanol bath to −5° C
3. filtrationThe mixture was filtered
4. additionSodium hydroxide (50% aqueous solution) was added until pH >12
5. customthe organic layer was removed
6. extractionThe aqueous phase was extracted with methylene chloride (2×6 L)
7. washthe combined organic layers washed with water (6 L portions) until pH=7-8
8. dry with materialThe organic layers were dried over magnesium sulfate (500 g) and charcoal (200 g) for 16 hours
9. filtrationfiltered
10. concentrationThe filtrate was concentrated to an oil
11. customcrystallized from isopropanol at −20° C.

ORD record

ord-71fb8237d79f47c49bcdf0a4ccb2b509

Source dataset

uspto-grants-2001_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06194420B1