Hydrochloric Acid → 5-Nitro-1-benzothiophene

Temperatur

190 °C

Copper (8.18 g, 0.129 mol) was added to a mechanically stirred slurry of 5-nitrobenzo[b]thiophene-2-carboxylic acid (28.73 g, 0.129 mol) and quinoxaline (160 mL). The thick mixture was heated to 190° C. Upon heating, stirring became easier, and at around 170° C. gas evolution was observed. Gas evolution ceased after 40 min and the reaction mixture was allowed to cool to r.t. overnight. The mixture was then poured over crushed ice and acidified with concentrated hydrochloric acid. The resulting brown suspension was warmed with diethyl ether (4×400 mL). The ether layers were combined, washed with 2 N aqueous hydrochloric acid (300 mL), water (300 mL) and brine (300 mL), and then separated, dried over sodium sulfate, filtered, and the solvent evaporated in vacuo. The crude yellow solid (26 g) was recrystallized from hot acetone (175 mL) to yield 5-nitrobenzo[b]thiophene (15.58 g, 68%) as pale yellow crystals. 1H NMR δ (d6-DMSO, 400 MHz) 7.63 (d, J=5.5 Hz, 1H), 7.95 (d, J=5.5 Hz, 1H), 8.08 (dd, J=9, 2 Hz, 1H), 8.20 (d, J=9 Hz, 1H), 8.75 (d, J=2 Hz, 1H).

1. temperatureUpon heating
2. customat around 170° C.
3. temperatureto cool to r.t. overnight
4. additionThe mixture was then poured
5. customover crushed ice
6. washwashed with 2 N aqueous hydrochloric acid (300 mL), water (300 mL) and brine (300 mL)
7. customseparated
8. dry with materialdried over sodium sulfate
9. filtrationfiltered
10. customthe solvent evaporated in vacuo
11. customThe crude yellow solid (26 g) was recrystallized from hot acetone (175 mL)

ORD-Eintrag

ord-514cd97e588647a7a4b65db435e28c49

Quelldatensatz

uspto-grants-2010_08

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07786132B2