Hydrochloric Acid → 3-Methyl-1,2-thiazole-4-carboxylic acid

To a solution of 3-methyl-isothiazole-4-carboxylic acid ethyl ester (method 53) (23.3 g, 136 mmol) in THF (200 mL) aqueous NaOH (6.5 g, 162 mmol, in 100 ml of water) was added and the mixture was stirred at room temperature for 16 h. The TLC of the reaction mixture showed the complete disappearance of the starting material. The reaction mixture was cooled in an ice bath and acidified to pH 5 using 6M HCl and the resultant mixture was extracted with ether (3×100 mL). The ether layers were combined, washed with water (100 mL), brine (100 mL), dried (Na2SO4) and concentrated to about 10 mL. Addition of hexanes to the above mixture resulted in the precipitation of the product which was filtered off, washed with hexanes and dried to provide the pure product as a tan powder. Yield 15.3 g (79%). 1H NMR (300 MHz) δ 2.39 (s, 3H), 8.98 (s, 1H).

1. temperatureThe reaction mixture was cooled in an ice bath
2. extractionthe resultant mixture was extracted with ether (3×100 mL)
3. washwashed with water (100 mL), brine (100 mL)
4. dry with materialdried (Na2SO4)
5. concentrationconcentrated to about 10 mL
6. additionAddition of hexanes to the above mixture
7. customresulted in the precipitation of the product which
8. filtrationwas filtered off
9. washwashed with hexanes
10. customdried

ORD record

ord-c63aa08483ae457c896a51b59577395c

Source dataset

uspto-grants-2009_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07498333B2