Hydrochloric Acid → Benzenethiol, 2-amino-3,4,6-trifluoro-, hydrochloride

Temperature

125 °C

A solution of 4,5,7-trifluoro-2-methylbenzothiazole (25.0 g, 123 mmol) in ethylene glycol (310 mL, 0.4 M) and 30% aq NaOH (310 mL, 0.4 M) was degassed using a nitrogen stream and subsequently heated to a gentle reflux (125° C.) for 3 h. The solution was cooled to 0° C. and acidified to pH 3-4 using conc. HCl (appox. 200 mL). The solution was extracted with ether (750 mL) and washed with water (200 mL). The organic layer was dried over Na2SO4, filtered and treated with 2,2-di-tert-butyl-4-methylphenol (0.135 g, 0.5 mol %). After concentrating to dryness, the crude product was dissolved in anhyd methanol (200 mL) and treated with an HCl solution in 1,4-dioxane (37 mL, 4 N, 148 mmol). The resulting mixture was concentrated to dryness, triturated with isopropylether (100 mL) and filtered to give 2-amino-3,4,6-trifluorothiophenol hydrochloride (19.3 g, 73%) as a light brown solid that was used without further purification. mp. 121-124° C.; Rf 0.43 (30% ethyl acetate in heptane); Anal. calcd for C6H5ClF3NS: C, 33.42; H, 2.34; N, 6.50; S, 14.87. Found C, 33.45; H, 2.27; N, 6.48; S, 14.96.

1. temperaturesubsequently heated to
2. temperatureThe solution was cooled to 0° C.
3. extractionThe solution was extracted with ether (750 mL)
4. washwashed with water (200 mL)
5. dry with materialThe organic layer was dried over Na2SO4
6. filtrationfiltered
7. additiontreated with 2,2-di-tert-butyl-4-methylphenol (0.135 g, 0.5 mol %)
8. concentrationAfter concentrating to dryness
9. dissolutionthe crude product was dissolved in anhyd methanol (200 mL)
10. concentrationThe resulting mixture was concentrated to dryness
11. customtriturated with isopropylether (100 mL)
12. filtrationfiltered

ORD record

ord-7827d8eea0e7445db43d5e8545675e07

Source dataset

uspto-grants-2002_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06420426B1