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Nitrobenzene



Nitrobenzene
Other names Nitrobenzol
Oil of mirbane
Identifiers
CAS number 98-95-3
RTECS number QJ0525000
SMILES C1=CC=C(C=C1)[N+](=O)[O-]
Properties
Molecular formula C6H5NO2
Molar mass 123.06 g/mol
Appearance colorless liquid
Density 1.199 g/cm3
Melting point

5.85 °C

Boiling point

210.9 °C

Solubility in water 0.19 g/100 ml at 20 °C
Hazards
EU classification Toxic (T)
Carc. Cat. 3
Repr. Cat. 3
Dangerous for the environment (N)
R-phrases R23/24/25, R40,
R48/23/24, R51/53, R62
S-phrases (S1/2), S28, S36/37,
S45, S61
Flash point 88 °C
Autoignition
temperature
525 °C
Related Compounds
Related compounds Aniline
Benzenediazonium
Nitrosobenzene
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Nitrobenzene, also known as nitrobenzol or oil of mirbane, is a poisonous organic compound with an almond odor and chemical formula C6H5NO2. This oily water-insoluble liquid is mainly produced as a precursor to aniline but in the laboratory It is used as a solvent and as a mild oxidizing agent.

Additional recommended knowledge

Contents

Uses

Approximately 98% of nitrobenzene is consumed in the production of aniline.[1] More specialized applications include rubber chemicals, pesticides, dyes, and pharmaceuticals. Nitrobenzene is also used in shoe and floor polishes, leather dressings, paint solvents, and other materials to mask unpleasant odors. Substitution reactions with nitrobenzene are used to form m-derivatives (Mannsville 1991; Sittig 1991)[citation needed]. Redistilled, as oil of mirbane, nitrobenzene has been used as an inexpensive perfume for soaps. A significant merchant market for nitrobenzene is its use in the production of the analgesic paracetamol (also known as acetaminophen) (Mannsville 1991)[citation needed]. Nitrobenzene is also used in Kerr cells, as it has an unusually large Kerr constant.

Nitrobenzene is readily converted to related derivatives such as azobenzene,[2] nitrosobenzene.[3], phenylhydroxylamine.[4]

Production

Nitrobenzene is prepared by nitration of benzene. The classic method involves treatment of benzene with a mixture of concentrated sulfuric acid, water, and nitric acid, called "mixed acid." Its production is one of the most dangerous processes conducted in the chemical industry due to the exothermicity of the reaction (ΔH = −117 kJ/mol).[1]

There were four producers of nitrobenzene in the United States in 1991: First Chemicals Corporation, Mobay, DuPont Chemicals, and Rubicon Inc. World capacity for nitrobenzene in 1985 was ca. 1.7×106 tonnes.[1]

Mechanism

The reaction pathway entails formation of an adduct between the Lewis acidic nitronium ion, NO2+, and the arene. The nitronium ion is generated in situ via the reaction of nitric acid and an acidic dehydration agent, typically sulfuric acid:

HNO3 + H+ NO2+ + H2O

References

  1. ^ a b c Gerald Booth "Nitro Compounds, Aromatic" in "Ullmann's Encyclopedia of Industrial Chemistry" 2007; John Wiley & Sons: New York.
  2. ^ Bigelow, H. E.; Robinson, D. B. (1955). "Azobenzene". Org. Synth.; Coll. Vol. 3: 103. 
  3. ^ G. H. Coleman, C. M. McCloskey, F. A. Stuart. "Nitrosobenzene". Org. Synth.; Coll. Vol. 3: 668. 
  4. ^ O. Kamm. "Β-Phenylhydroxylamine". Org. Synth.; Coll. Vol. 1: 445. 
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Nitrobenzene". A list of authors is available in Wikipedia.
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