Reaction #2028886

Reaction equation

4-(2-Thienyl)butyric acid

acetic anhydride

phosphoric acid

→

oil

Yield 88.9%

4-keto-4,5,6,7-tetrahydrothianaphthene

Yield 88.9%

Solvents

water

Conditions

Workup

1. 1
   Temperatureheated
2. 2
   Temperatureto reflux for 3.2 hours
3. 3
   Extractionextracted with ethyl acetate
4. 4
   Washwashed with brine
5. 5
   Dryingdried over MgSO4
6. 6
   Concentrationconcentrated in vacuo

Procedure

4-(2-Thienyl)butyric acid (28.42 g, 167 mmol) was placed in a round bottom flask with acetic anhydride (30 mL) and phosphoric acid (0.6 mL), and heated to reflux for 3.2 hours. The reaction mixture was poured into 100 mL of water, extracted with ethyl acetate, washed with brine, dried over MgSO4, and concentrated in vacuo to give a brown oil (22.60 g) which was vacuum distilled (1 mm Hg, 107°-115° C.) to give a white solid (13.08 g, 51%): mp 34°-40° C.); 1H NMR (CDCl3) 300 MHz 7.29 (d, J=5.2 Hz, 1H), 6.99 (d, J=5.2 Hz, 1H, 2.95 (t, J=6.0 Hz, 2H), 2.47(m, 2H), 2.13(m, 2H). M+H=153.

Source