Dinitrobenzene

Dinitrobenzenes are chemical compounds composed of a benzene ring and two nitro group (-NO2) substituents. The three possible arrangements of the nitro groups afford three isomers, 1,2-dinitrobenzene, 1,3-dinitrobenzene, and 1,4-dinitrobenzene. Each isomer has the chemical formula C6H4N2O4 and a molar mass of about 168.11 g/mol. 1,3-Dinitrobenzene is the most common isomer and it is used in the manufacture of explosives.

Properties

The dinitrobenzenes are all crystalline solids. The boiling points of the three isomers are relatively close; however, the melting points significantly differ. 1,4-Dinitrobenzene, which has the highest symmetry, has the highest melting point.

Dinitrobenzenes
IUPAC name 1,2-Dinitrobenzene 1,3-Dinitrobenzene 1,4-Dinitrobenzene
Other names o-Dinitrobenzene m-Dinitrobenzene p-Dinitrobenzene
Chemical structure
CAS number 528-29-0 99-65-0 100-25-4
25154-54-5 (Unspecified isomers)[1]
PubChem CID 10707 from PubChem CID 7452 from PubChem CID 7492 from PubChem
Chemical formula C6H4N2O4
Molar mass 168.11 g/mol
Physical state solid
Appearance Colorless crystals Yellowish crystals Colorless crystals
Melting point 118 °C[2] 89.6 °C[3] 174 °C[4]
Boiling point 318 °C[2] 297 °C[3] 299 °C[5]
Density 1.565 g/cm3 (17 °C)[5] 1.575 g/cm3 (18 °C)[5] 1.625 g/cm3 (18 °C)[5]
Vapor pressure 0.08 Pa (30 °C)[6] 0.07 Pa (30 °C)[6]
0.34 Pa (50 °C)[6] 0.23 Pa (50 °C)[6]
Solubility Insoluble in water
GHS hazards[7]
R phrases R26/27/28-R33-R50/53
S phrases (S1/2)-S28-S36/37-S45-S60-S61

Preparation

1,3-Dinitrobenzene is accessible by nitration of nitrobenzene. The reaction proceeds under acid catalysis using sulfuric acid. The directing effect of the nitro group of nitrobenzene leads to 93% of the product resulting from nitration at the meta-position. The ortho- and para-products occur in only 6% and 1%, respectively.[8]

Reactions

Reduction of 1,3-dinitrobenzene with sodium sulfide in aqueous solution leads to 3-nitroaniline. Further reduction with iron and hydrochloric acid (HCl) gives m-phenylenediamine.[9]

References

  1. ↑ Record of CAS RN 25154-54-5 in the GESTIS Substance Database of the IFA
  2. 1 2 Record of CAS RN 528-29-0 in the GESTIS Substance Database of the IFA, accessed on 11 March 2008.
  3. 1 2 Record of CAS RN 99-65-0 in the GESTIS Substance Database of the IFA, accessed on 11 March 2008.
  4. ↑ Record of CAS RN 100-25-4 in the GESTIS Substance Database of the IFA, accessed on 11 March 2008.
  5. 1 2 3 4 Brockhaus ABC Chemie, VEB F.A. Brockhaus Verlag, Leipzig 1971.
  6. 1 2 3 4 Félix-Rivera, Hilsamar (2011). "Triacetone triperoxide thermogravimetric study of vapor pressure and enthalpy of sublimation in 303–338K temperature range". Thermochimica Acta. 514 (1-2): 37–43. doi:10.1016/j.tca.2010.11.034.)
  7. ↑ Globally Harmonized System of Classification and Labelling of Chemicals (Second revised ed.), New York and Geneva: United Nations, 2007, ISBN 978-92-1-116957-7, ST/SG/AC.10/30/Rev.2
  8. ↑ Joachim Buddrus (2003). Grundlagen der organischen Chemie (3 ed.). Berlin: de Gruyter. p. 360. ISBN 3-11-014683-5.
  9. ↑ Hans Beyer and Wolfgang Walter (1981). Lehrbuch der Organischen Chemie (19 ed.). Stuttgart: S. Hirzel Verlag. pp. 536, 542. ISBN 3-7776-0356-2.
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