Sodium Bicarbonate → 4-Chlorothiophene-2-carboxylic acid

A 300 mg (1.278 mmol) sample of 4-chloro-3-trimethylsilyl-2-thiophene carboxylic acid was dissolved in 10 mL of tetrahydrofuran with 0.3 mL of water and cooled to -5° C. (ice/brine bath). A 2.6 mL aliquot of the 1M tetrahydrofuran solution of tetra-n-butyl ammonium fluoride was slowly added to the reaction solution. After 4 hours the reaction was poured into 50 mL of 5% aqueous sodium bicarbonate. The entire reaction solution was transferred to a separatory funnel and washed with ethyl acetate (2×25 mL). The basic aqueous solution was acidified with concentrated hydrochloric acid to pH2 and then extracted with ethyl acetate (3×30 mL). The organic extract was then dried (sodium sulfate), filtered, and evaporated to 216 mg of product as a white solid. Recrystallization using hot heptane gave 85 mg of pure crystalline product, mp 138° C.

1. customThe entire reaction solution was transferred to a separatory funnel
2. washwashed with ethyl acetate (2×25 mL)
3. extractionextracted with ethyl acetate (3×30 mL)
4. extractionThe organic extract
5. dry with materialwas then dried (sodium sulfate)
6. filtrationfiltered
7. customevaporated to 216 mg of product as a white solid
8. customRecrystallization

ORD record

ord-8005101ab67c4d15aec07a456f04fb02

Source dataset

uspto-grants-1997_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05648502