2,4-Dinitrotoluene

2,4-Dinitrotoluene (DNT) or dinitro is an organic compound with the formula C7H6N2O4. This pale yellow crystalline solid is well known as a precursor to trinitrotoluene (TNT) but is mainly produced as a precursor to toluene diisocyanate.

2,4-Dinitrotoluene
Names
IUPAC name
1-methyl-2,4-dinitro benzene
Other names
Dinitrotoluol, Methyldinitrobenzene
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.004.046
KEGG
UNII
UN number Molten: 1600
Solid or liquid: 2038
Properties
C7H6N2O4
Molar mass 182.134 g/mol
Appearance Pale yellow to orange crystalline solid
Density 1.52 g/cm3[1]
Melting point 70 °C (158 °F; 343 K)[1]
Boiling point Decomposes at 250–300 °C[1]
Vapor pressure 1.47X10-4 mm Hg @ 22 C

[2]

Hazards
Main hazards carcinogen, combustible (though difficult to ignite)[3]
Flash point 207 °C; 404 °F; 480 K
Lethal dose or concentration (LD, LC):
216 mg/kg (oral, rat, 3,5-isomer)
1,954 mg/kg (oral, mouse, 2,4-isomer)[4]
27 mg/kg (2,4 isomer, cat, oral)[4]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 1.5 mg/m3 [skin][3]
REL (Recommended)
 Ca TWA 1.5 mg/m3 [skin][3]
IDLH (Immediate danger)
 Ca [50 mg/m3][3]
Explosive data
Shock sensitivity Insensitive
Friction sensitivity Very low
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Isomers of dinitrotoluene

Six positional isomers are possible for dinitrotoluene. The most common one is 2,4-dinitrotoluene. The nitration of toluene gives sequentially mononitrotoluene, DNT, and finally TNT. 2,4-DNT is the principal product from dinitration, the other main product being about 30% 1,3-DN2-T. The nitration of 4-nitrotoluene gives 2,4-DNT.[5]

Applications

Most DNT is used in the production of toluene diisocyanate, which is used to produce flexible polyurethane foams. DNT is hydrogenated to produce 2,4-toluenediamine, which in turn is phosgenated to give toluene diisocyanate. In this way, about 1.4 billion kilograms are produced annually, as of the years 1999–2000.[6] Other uses include the explosives industry. It is not used by itself as an explosive, but some of the production is converted to TNT.

Dinitrotoluene is frequently used as a plasticizer, deterrent coating, and burn rate modifier in propellants (e.g., smokeless gunpowders). As it is carcinogenic[3] and toxic, modern formulations tend to avoid its use. In this application it is often used together with dibutyl phthalate.

Toxicity

Dinitrotoluenes are highly toxic with a threshold limit value (TLV) of 1.5 mg/m3.[7] It converts hemoglobin into methemoglobin.

2,4-Dinitrotoluene is also a listed hazardous waste under 40 CFR 261.30. Its United States Environmental Protection Agency (EPA) Hazardous Waste Number is D030. The maximum concentration that may be contained to not have toxic characteristics is 0.13 mg/L.

References
  1. Record of 2,4-Dinitrotoluene in the GESTIS Substance Database of the Institute for Occupational Safety and Health, accessed on 9. October 2007.
  2. Pella, PA. J. Chem. Thermodyn. 9: 301-305, 1977
  3. NIOSH Pocket Guide to Chemical Hazards. "#0235". National Institute for Occupational Safety and Health (NIOSH).
  4. "Dinitrotoluene (mixed isomers)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH). 4 December 2014. Retrieved 17 March 2015.
  5. Gerald Booth (2007). "Nitro Compounds, Aromatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a17_411.
  6. Six, C.; Richter, F. "Isocyanates, Organic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a14_611.
  7. NIOSH Pocket Guide to Chemical Hazards - Dinitroluene
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