Sulfuric Acid → 3-Fluoro-4-nitrobenzoic acid

To a solution of 3-fluoro-4-nitrotoluene (22.45 g, 144.7 mmol) and sodium dichromate dihydrate (60.38 g, 202.6 mmol) in water at 0° C. was added concentrated sulfuric acid (140 mL) dropwise over 3 h. When the addition was complete, the solution was allowed to warm to room temperature over 1 h, and then brought to 90° C. for 1 h. The mixture was allowed to cool to room temperature, diluted with 300 mL water and extracted with ethyl acetate (3×250 mL). The combined organic extracts were concentrated down to 300 mL and extracted with 1 N NaOH (3×250 mL). The aqueous extracts were acidified with 6 N HCl and extracted with ethyl acetate (3×300 mL). The combined organic extracts were dried over MgSO4 and concentrated to give a gummy solid. Trituration with hexane gave the 3-fluoro-4-nitrobenzoic acid as a solid that was collected by filtration (6.51 g, 24%).

1. additionWhen the addition
2. temperatureto cool to room temperature
3. extractionextracted with ethyl acetate (3×250 mL)
4. concentrationThe combined organic extracts were concentrated down to 300 mL
5. extractionextracted with 1 N NaOH (3×250 mL)
6. extractionextracted with ethyl acetate (3×300 mL)
7. dry with materialThe combined organic extracts were dried over MgSO4
8. concentrationconcentrated
9. customto give a gummy solid

ORD record

ord-0e50e05572de482fa09d3f1adac77091

Source dataset

uspto-grants-2006_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07138420B2