quinoxaline

structural formula

• numbering system
• physical property data
• toxicological data
• ecological data
• molecular structure data
• computing chemical data
• more
  • properties and stability
  • storage method
  • synthesis method
  • purpose

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.