反应详情

FIG. 13 shows the reaction pathway. This reaction should be carried out in a fume hood. In a 500 mL round-bottomed flask with a 24/40 ground-glass joint attached to an efficient reflux condenser and under a nitrogen atmosphere, a magnetically stirred slurry consisting of 8.10 g (0.050 mol) of 1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarbonitrile, 4.0 mL of dimethylformamide 306 and 160 mL of thionyl chloride 1301 was heated. Gas evolution began at ca. 62° [SO2 & HCl gasses evolved]. After about 3.5 hours, the solid had dissolved and the temperature had risen to 70°. After cooling to room temperature, a Dry Ice/acetone bath was applied until the temperature of the reaction medium was −65°. The crystals which formed were collected by rapid filtration of the cold slurry through a sintered-glass filter under a nitrogen blanket. The solid was washed twice with 150-ml portions of cold diethyl ether and air-dried to give 7 g (70%) of 2,3-dichloro-5,6-dicyanopyrazine 301, mp 180-182°. Crystallization of the product may be accomplished if dark, from ˜50 mL of chloroform with carbon treatment to give 5.5 g of purified product.

1. customThis reaction
2. customIn a 500 mL round-bottomed flask with a 24/40 ground-glass joint attached to an efficient reflux condenser and under a nitrogen atmosphere
3. temperaturewas heated
4. custombegan at ca. 62°
5. dissolutionthe solid had dissolved
6. customhad risen to 70°
7. customa Dry Ice/acetone bath was applied until the temperature of the reaction medium
8. customwas −65°
9. customThe crystals which formed
10. filtrationwere collected by rapid filtration of the cold slurry through a sintered-glass
11. filtrationfilter under a nitrogen blanket
12. washThe solid was washed twice with 150-ml portions of cold diethyl ether
13. customair-dried