Which reagent is used for the nitration of an aromatic compound?
The key reagent for nitration is nitric acid, HNO3. By itself, nitric acid is a relatively slow-acting electrophile, especially in the presence of a poor nucleophile such as benzene. [Note – in the case of phenol and other aromatic rings with strongly activating groups, HNO3 by itself is sufficient for nitration].
What is aromatic nitration?
Aromatic nitration is a class of industrially important reactions for the synthesis of chemical intermediates with direct relevance to dyes, plastics, and pharmaceuticals. The nitration reagent is a mixture of concentrated nitric and concentrated sulfuric acid (333). Obviously, a more benign route would be desirable.
How do you prove that aromatic is benzene?
Originally, benzene was considered aromatic because of its smell: it has an “aromatic” odor. It is now considered aromatic because it obeys Hückel’s rule: 4n+2 = number of π electrons in the hydrocarbon, where n must be an integer. In the case of benzene, we have 3 π bonds (6 electrons), so 4n+2=6 .
Which catalyst is used in nitration of benzene?
The concentrated sulfuric acid is acting as a catalyst.
What is mechanism of nitration of benzene?
Benzene reacts with nitric acid and sulphuric acid to form nitrobenzene. It is an example of electrophilic aromatic substitution reaction. One hydrogen atom of benzene ring is replaced with nitro group. Nitric acid reacts with sulphuric acid to form nitronium ions.
What is benzene nitration?
The nitration of benzene Nitration happens when one (or more) of the hydrogen atoms on the benzene ring is replaced by a nitro group, NO2. Benzene is treated with a mixture of concentrated nitric acid and concentrated sulfuric acid at a temperature not exceeding 50°C.
Which is the electrophile in the nitration of benzene?
The electrophile is the “nitronium ion” or the “nitryl cation”, NO+2. This is formed by reaction between the nitric acid and the sulphuric acid.
How is the electrophile generated in the nitration of benzene?
The arenium ion loses a proton and forms nitrobenzene. Hence, the generation of electrophile in nitration of benzene takes place by protonation of nitric acid with the help of sulphuric acid. The arenium ion is the resonance stabilized carbocation which forms during the electrophilic substitution in an aromatic ring.
What is the nitration of benzene?
The nitration of benzene is an electrophilic aromatic substitution reaction, in which a nitro group (-NO 2) is introduced onto a benzene ring. This reaction proceeds via the formation of an electrophilic nitronium ion (NO 2+) from nitric acid (HNO 3 ), resulting from proton transfer from sulfuric acid (H 2 SO 4 ).
How do you re-aromatize a benzene ring?
As such, there is a strong drive to re-aromatize the benzene ring. This is accomplished by removing the hydrogen atom on the benzene carbon bonded to the new nitro group.
How do nitrogen and oxygen react with benzene?
This leads to the cleavage of the bond between the nitrogen and the protonated oxygen, with the electrons going onto the oxygen (neutralizing the charge), and releasing water. This forms the electrophilic nitronium ion required for reaction with benzene: With the nitronium ion electrophile formed, it can react with the benzene ring.
How do you change a benzene to a nitro group?
This is accomplished by removing the hydrogen atom on the benzene carbon bonded to the new nitro group. The water molecule released earlier can act as a base, donating a lone pair to this hydrogen, breaking the C-H bond, and re-forming the double bond in the benzene ring (or more accurately, re-establishing the aromaticity of the benzene ring).