Sulfamic Acid → 3-Chloro-4-hydroxy-5-methylbenzoic acid

Temperature

12 °C

A solution of sulfamic acid (11.8 g, 121.5 mmol) in water (25 mL) was added with vigorous stirring to 3-chloro-4-hydroxy-5-methylbenzaldehyde (16.00 g, 93.8 mmol) in tert-butanol (100 mL). The mixture was cooled (˜12° C.) and a solution of sodium chlorite (12.00 g, 106.1 mmol) in water (25 mL) was added in5 mL portions with vigorous stirring. The reaction was exothermic and the temperature at the end of the addition was approximately 50° C. The two layers were separated and the aqueous layer was extracted with ether (2×50 mL). The organic layers were washed with brine and evaporated to dryness. Water was added, and the mixture was stirred and filtered. The solid was dissolved in warm ether (250 mL), and the solution was dried, filtered, concentrated to 100 mL, and cooled in the freezer (approx. −20 ° C.). Filtration and washing with cold ether gave 3-chloro-4-hydroxy-5-methylbenzoic acid (9.10 g, 52%), as a yellow solid, mp 242-244° C.

1. additionthe temperature at the end of the addition
2. customwas approximately 50° C
3. customThe two layers were separated
4. extractionthe aqueous layer was extracted with ether (2×50 mL)
5. washThe organic layers were washed with brine
6. customevaporated to dryness
7. additionWater was added
8. filtrationfiltered
9. dissolutionThe solid was dissolved in warm ether (250 mL)
10. customthe solution was dried
11. filtrationfiltered
12. concentrationconcentrated to 100 mL
13. temperaturecooled in the freezer (approx. −20 ° C.)
14. filtrationFiltration
15. washwashing with cold ether

ORD record

ord-e7528e2f0e3744d6ae3486e38c8a421c

Source dataset

uspto-grants-2001_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06331640B1