Nitration

Nitration occurs with aromatic organic compounds via an electrophilic substitution mechanism involving the attack of the electron-rich benzene ring by the (nitryl) nitronium ion.

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Benzene is nitrated by refluxing with concentrated sulfuric acid and concentrated nitric acid at 50°C.

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(1) 2H2SO4 + HNO3 → 2HSO42- + NO2+ + H3O+

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(2) C6H6 + NO2+ → C6H5NO2 + H+

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(3) H+ + H3O+ + 2HSO42- → H2O + 2H2SO4

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The sulfuric acid is regenerated and hence acts as a catalyst.

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The formation of a nitronium ion (the electrophile) from nitric acid and sulfuric acid is shown below:

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Selectivity is always a challenge in nitrations, Fluorenone nitration is selective and yields a tri-nitro compound or tetra-nitro compound by tweaking reaction conditions just slightly. Another example of trinitration can be found in the synthesis of phloroglucinol.

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Other nitration reagents include nitronium tetrafluoroborate which is a true nitronium salt. This compound can be prepared from hydrogen fluoride, nitric acid and boron trifluoride . Aromatic nitro compounds are important intermediates to anilines by action of a reducing agent.

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Electrophilic substitution: Electrophilic substitution reactions are chemical reactions in which an electrophile displaces another group, typically but not always hydrogen. Electrophilic substitution is characteristic of aromatic compounds. Electrophilic aromatic substitution is an important way of introducing functional grou...

Nitronium ion: The nitronium ion, 2+, is not stable enough to exist in normal conditions, but it is used extensively in the nitration of other substances. The ion is created in situ by mixing sulfuric acid and nitric acid according to the equilibrium:...

C: :This page is about the letter C itself. For other uses of C, see C (disambiguation)....