7,10-Diazafluoranthene (Acenaphtho[1,2-b]pyrazine)

7,10-Diazafluoranthene has been reported to be strongly mutagenic in an Ames-test [1], but no details regarding neither the synthesis nor other properties have been published.

7,10-Diaza-8,9-dihydrofluoranthene (1).(Compare to [2])

Acenaphtene quinone (4.1g; 23 mmol) was dissolved in refluxing MeOH (170 mL), a small portion of the quinone sometimes remained undissolved. Ethane-1,2-diamine (1.7 mL; 25 mmol) was slowly added. This mixture was refluxed for 1h, cooled to room temperature and evaporated to dryness.

The dark brownish powder was dissolved in a small portion of MeOH and cooled in an ice bath. Water was slowly added until a fog of colloid precipitate became visible, which was removed by filtration. The filtrate was extracted twice with CH₂Cl₂ (1 ´ 70, 1 ´ 50 mL). The combined organic solutions were dried over MgSO₄, filtered and concentrated in vacuo to give almost pure 1 in quantitative yield. Yellow powder. Mp 94.4-96.0 °C.

M/z: M⁺ = 206 (70) ); 178 (90); 151 (20); 125 (5); 103 (3).

¹H NMR (400 MHz, CDCl₃, d, ppm): 7.96 (d, J = 8.4 Hz); 7.94 (d, J = 7.0 Hz); 7.69 (dd, J₁ = 7.2 Hz; J₂ = 7.0 Hz); 3.91 (s, 4 H).

¹³C NMR (100 MHz, CDCl₃, d, ppm): 158.6; 141.5; 131.7; 130.7; 128.5; 128.4; 118.7; 45.0.

7,10-Diazafluoranthene (2).

7,10-Diaza-8,9-dihydrofluoranthene (1) (5.35 g ; 26 mmol) was dissolved in dioxane (270 mL). A solution of DDQ (6.0g; 26.5 mmol) in dioxane (150 mL) was added, and the mixture was refluxed for 30 min. After evaporation to dryness, the mixture was dissolved in CH₂Cl₂ (200 mL) and washed with a 0.3 M solution of Na₂SO₃ in water (40 mL). The solid material was removed by filtration, and dried in vacuo. The organic phase was evaporated to dryness, and combined with the material from the filtration. This mixture was subjected to Soxhlet-chromatography [3] on Aluminium oxide (Woelm, basic activity I) with CH₂Cl₂ as eluent to give 7,10-diazafluoranthen as yellow crystals in 74% yield (3.92 g) melting 145.0-147.1°C.

M/z: M⁺ = 204 (100); 178 (74); 151 (24); 102 (9); 75 (16).

An analytical sample obtained by sublimation. (100 °C/ 0.01 mmHg) had:

Calcd. for C₁₄H₈N₂: 82.34% C; 3.95% H; 13.72% N

Found 82.36% C; 4.07% H; 13.47% N

Mp: 145.0-147.1 °C.

¹H NMR (400 MHz, CDCl₃, d, ppm): 8.46 (s, 2 H); 8.28 (d, J = 7.0 Hz); 8.04 (d, J = 8.2 Hz); 7.78 (dd, J₁ = 7.0 Hz; J₂ = 7.0 Hz)

¹³C NMR (100 MHz, CDCl₃, d, ppm): 153.6; 141.1; 132.3; 131.4; 129.6; 129.4; 128.3; 122.7.