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 in 5 mL portions with vigorous stirring. The reaction was exothermic and the temperature at the end of the addition was approximately 50° C. The layers were separated and the aqueous layer was extracted with diethyl 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 diethyl ether (250 mL) and the solution was dried, filtered, concentrated to 100 mL and cooled in the freezer (approx. −20° C.). The resulting yellow crystalline solid was filtered off and washed with cold diethyl ether to furnish 3-chloro-4-hydroxy-5-methylbenzoic acid (9.10 g, 52% yield), mp 242-244° C.

1. additionthe temperature at the end of the addition
2. customwas approximately 50° C
3. customThe layers were separated
4. extractionthe aqueous layer was extracted with diethyl 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 diethyl ether (250 mL)
10. customthe solution was dried
11. filtrationfiltered
12. concentrationconcentrated to 100 mL
13. temperaturecooled in the freezer (approx. −20° C.)
14. filtrationThe resulting yellow crystalline solid was filtered off
15. washwashed with cold diethyl ether

ORD record

ord-3055ae862a8049d4a5589cc9c846fe50

Source dataset

uspto-grants-2003_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06515124B2