ChemicalBook CAS DataBase List 4-BROMO-5-METHYL-2-THIOPHENECARBOXYLIC ACID

4-BROMO-5-METHYL-2-THIOPHENECARBOXYLIC ACID synthesis

6synthesis methods

Product Name:4-BROMO-5-METHYL-2-THIOPHENECARBOXYLIC ACID
CAS Number:29421-99-6
Molecular formula:C6H5BrO2S
Molecular Weight:221.07

29421-73-6

4-BROMO-5-METHYL-2-THIOPHENECARBOXYLIC ACID

29421-99-6

a) 27.65 g (108 mmol) of 2-methyl-3,5-dibromothiophene (prepared according to the method of Kano, S. et al, Heterocycles 20(10):2035, 1983) was dissolved in 280 mL of anhydrous tetrahydrofuran and cooled to -78°C. To this solution was added, over a 10-minute period, 54 mL (108 mmol) of a 2 M n-butyllithium in cyclohexane solution. After stirring at -78°C for 20 min, dry carbon dioxide gas was passed into the reaction system for 1.5 hr while the mixture was allowed to warm slowly to room temperature. Upon completion of the reaction, 100 mL of 6N hydrochloric acid was carefully added. The organic and aqueous layers were separated and the aqueous layer was extracted with ether (4 x 50 mL). All organic layers were combined, washed with brine and dried with anhydrous sodium sulfate. The solvent was removed by distillation under reduced pressure to give 22.4 g (94% yield) of 4-bromo-5-methylthiophene-2-carboxylic acid as an off-white solid.1H-NMR (DMSO-d6; 300 MHz) δ 13.34 (br s, 1H), 7.61 (s, 1H), 2.41 (s, 3H).

1918-79-2
244 suppliers
$8.00/5g

29421-99-6
61 suppliers
$60.00/10mg

Yield:29421-99-6 100%

Reaction Conditions:

with iron(III) chloride;bromine in acetic acid at 25; for 5 h;

Steps:

9

A solution of bromine (725 uL, 14.1 mmol) in AcOH (2.8 ml.) was added dropwise to δ-methyl^-thiophenecarboxylic acid (2 g, 14.1 mmol) and FeCI₃ (456 mg, 2.81 mmol) in AcOH (28 ml.) at 25 ⁰C. After 5h, the solution was poured onto ice and the precipitate was filtered and washed with water affording the title compound (3 g, quant.) as a yellow powder: LCMS (ES) m/z 222 (M+H)⁺.

References:

WO2008/98104,2008,A1 Location in patent:Page/Page column 81

29421-73-6 Synthesis

29421-73-6
97 suppliers
$19.00/1g

29421-99-6
61 suppliers
$60.00/10mg

References