Dinitrobenzene

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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[edit]

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 O-Dinitrobenzol.svg M-Dinitrobenzol.svg P-Dinitrobenzol.svg
CAS number 528-29-0 99-65-0 100-25-4
25154-54-5 (Unspecified isomers)[1]
PubChem PubChem 10707 PubChem 7452 PubChem 7492
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] GHS-pictogram-skull.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
R phrases R26/27/28-R33-R50/53
S phrases (S1/2)-S28-S36/37-S45-S60-S61

Preparation[edit]

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]

Nitration of nitrobenzene to produce dinitrobenzenes

Reactions[edit]

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[edit]

  1. ^ Record of CAS RN 25154-54-5 in the GESTIS Substance Database of the IFA
  2. ^ a b Record of CAS RN 528-29-0 in the GESTIS Substance Database of the IFAError in template * unknown parameter name (Template:GESTIS): 'Datum'.
  3. ^ a b Record of CAS RN 99-65-0 in the GESTIS Substance Database of the IFAError in template * unknown parameter name (Template:GESTIS): 'Datum'.
  4. ^ Record of CAS RN 100-25-4 in the GESTIS Substance Database of the IFAError in template * unknown parameter name (Template:GESTIS): 'Datum'.
  5. ^ a b c d Brockhaus ABC Chemie, VEB F.A. Brockhaus Verlag, Leipzig 1971.
  6. ^ a b c d 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.