Ammonia → 1,8-Dichloroanthracene

Participants

Reaction Conditions

Reaction Steps

A suspension of 1,8-dichloroanthraquinone 1 (10.0 g, 36.1 mmol) and Zinc dust (50.0 g, 765 mmol) in 200 ml of aqueous 28% NH3 was stirred for 3 h at 100° C. After cooling to room temperature, the resulting solid was separated by suction filtration. A CH2Cl2 solution of the resulting crude solid was combined with the CH2Cl2 extract of the supernatant liquid, and the mixture was dried over MgSO4 and concentrated under vacuo. The residual crude solid was dissolved in a mixture of 500 ml of isopropanol and 50 ml of 12 M HCl. After the resulting solution had been refluxed for 3 h, it was concentrated and partitioned between CH2Cl2 and 5% NaHCO3. The organic layer was collected and dried over MgSO4. The solvent was evaporated, and the crude solid product was recrystallized from a CH2Cl2-hexane mixture. The collected product was allowed to dry in the air for 24 h to provide 5.5 g (62%) of 1,8-dichloroanthracene 2 as yellow needles: mp 153° C. IR (KBr): ν=1617, 1547, 1438, 1300, 1210, 953, 872, 775, 720, 678; 1H NMR (CDCl3, 400 MHz) δ=7.25-7.88 (m; 6H, ArH), 8.36 (s; 1H, ArH-10), 9.16 (s; 1H, ArH-9); 13C NMR (CDCl3, 400 MHz) δ=120.99, 125.68, 126.04, 127.33, 127.61, 132.63; MS (EI) m/z (%)=246 (100) [M+], 248 (65); HRMS (EI) Calcd. For C14H8Cl2 [M+] 246.0003, Found 246.0001.

Provenance & Evidence