Quinoxaline
Structural formula
| Business number | 0239 |
|---|---|
| Molecular formula | C8H6N2 |
| Molecular weight | 130.15 |
| label |
benzopyrazine, Quinocillin, 1,4-diazonaphthalene, p-naphthyridine, 1,4-Benzodiazine, benzopyrazine |
Numbering system
CAS number:91-19-0
MDL number:MFCD00006719
EINECS number:202-047-4
RTECS number:VD1225000
BRN number:109351
PubChem number:24853610
Physical property data
1. Properties: white crystal.
2. Density (g/mL, 40/4℃): 1.1334
3. Relative vapor density (g/mL, air=1): Undetermined
4. Melting point (ºC): 30
5. Boiling point (ºC, normal pressure): Undetermined
6. Boiling point (ºC, 2.26kpa): 112～115
7. Refractive index: 1.6231
8. Flash point (ºC): Undetermined
9. Specific rotation (º): Undetermined
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10. Autoignition point or ignition temperature (ºC): Undetermined
11. Vapor pressure (kPa, 25ºC): Undetermined
12. Saturated vapor pressure (kPa, 60ºC): Undetermined
13. Heat of combustion (KJ/mol): Undetermined
14. Critical temperature (ºC): Undetermined
15. Critical pressure (KPa): Undetermined
16. Log value of oil-water (octanol/water) partition coefficient: Undetermined
17. Explosion upper limit (%, V /V): Undetermined
18. Lower explosion limit (%, V/V): Undetermined
19. Solubility: Soluble in water, ethanol, ether, acetone and benzene .
Toxicological data
None
Ecological data
None
Molecular structure data
1. Molar refractive index: 40.27
2. Molar volume (cm3/mol): 109.9
3. Isotonic specific volume (90.2K ): 299.4
4. Surface tension (dyne/cm): 54.8
5. Polarizability (10-24cm3): 15.96
Compute chemical data
1. Reference value for hydrophobic parameter calculation (XlogP): None
2. Number of hydrogen bond donors: 0
3. Number of hydrogen bond acceptors: 2
4. Number of rotatable chemical bonds: 0
5. Number of tautomers: none
6. Topological molecule polar surface area 25.8
7. Number of heavy atoms: 10
8. Surface charge: 0
9. Complexity: 99.8
10. Number of isotope atoms: 0
11. Determine the atomsNumber of stereocenters: 0
12. Number of uncertain atom stereocenters: 0
13. Determined number of stereocenters of chemical bonds: 0
14 .The number of uncertain chemical bond stereocenters: 0
15. The number of covalent bond units: 1
Properties and stability
Weakly alkaline, pKa≈0.8 (water, 20℃). The melting point of hydrogen chloride salt is 184℃, and the melting point of sulfate is 186~187℃. Forms quaternary ammonium salt with methyl iodide (melting point 175°C). It is difficult to carry out substitution reaction with electrophilic reagents, and its reaction with nucleophiles is similar to that of pyrazine.
Storage method
Should be sealed and stored in a cool place.
Synthesis method
It is produced by the reaction of catechol and ethylenediamine, and the product is then dehydrogenated. Or it is obtained by cyclization of o-phenylenediamine and glyoxal: add water to the reaction pot, add sodium bisulfite, stir, slowly add glyoxal, the temperature rises to 75-80°C, and white crystals precipitate. Continue stirring for 10 minutes, add water and o-phenylenediamine, and keep it at 75-80°C for 1 hour. Cool to 50°C, neutralize with sodium carbonate to pH=8, heat to 60°C, let stand and separate the water layer to obtain benzopyrazine with a content of 80%, and a yield of 90%.
Purpose
Used as a reagent for organic synthesis. Used as an intermediate for the anti-tuberculosis drug pyrazinamide.
