Reaction #2358489

Reaction equation

methyl 5-(trifluoromethyl)benzo[b]thiophene-2-carboxylate

lithium hydroxide monohydrate

water

→

5-(trifluoromethyl)benzo[b]thiophene-2-carboxylic acid

Yield 96.2%

Solvents

methanol

Conditions

Workup

1. 1
   TemperatureThe reaction mixture was cooled to room temperature
2. 2
   Concentrationconcentrated under reduced pressure
3. 3
   workup.ADDITIONTo the obtained residue was added water
4. 4
   Washwashed with tert-butyl methyl ether 3 times
5. 5
   workup.ADDITIONTo the aqueous layer was added concentrated hydrochloric acid
6. 6
   Extractionextracted with tert-butyl methyl ether 3 times
7. 7
   WashThe combined organic layer was washed with saturated aqueous sodium chloride solution
8. 8
   Dryingdried over magnesium sulfate
9. 9
   Concentrationconcentrated under reduced pressure

Procedure

A mixture of 10.0 g of methyl 5-(trifluoromethyl)benzo[b]thiophene-2-carboxylate, 1.80 g of lithium hydroxide monohydrate, 30 ml of water and 90 ml of methanol was stirred at 75° C. for 1 hour. The reaction mixture was cooled to room temperature and then concentrated under reduced pressure. To the obtained residue was added water, and washed with tert-butyl methyl ether 3 times. To the aqueous layer was added concentrated hydrochloric acid, and then extracted with tert-butyl methyl ether 3 times. The combined organic layer was washed with saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then concentrated under reduced pressure to obtain 9.10 g of 5-(trifluoromethyl)benzo[b]thiophene-2-carboxylic acid.

Source