Role of HNO3 in nitration of benzene

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In summary, the conversation discusses the dissociation of HNO3 into NO2+ and OH- ions, and the question of why it is considered a proton donor (acid) instead of an alkaline. The answer is that HNO3 is a strong acid that can easily donate a proton, but the dissociation process also requires the presence of a stronger acid, such as sulfuric acid, to help create a good leaving group.
  • #1
desmond iking
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Homework Statement


in this case, the HNO3 can be dissociated into NO2+ and OH- ion. what makes it a proton donor. p/s : the ans is HNO3 is a proton donor for this question.


Homework Equations





The Attempt at a Solution



since the HNO3 can be dissociated into NO2+ and OH- ion, why it 's called as proton donor (acid), i would called it as alkaline... can someone explain on this plaese?
 

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  • #2
desmond iking said:

Homework Statement


in this case, the HNO3 can be dissociated into NO2+ and OH- ion. what makes it a proton donor. p/s : the ans is HNO3 is a proton donor for this question.

Homework Equations


The Attempt at a Solution



since the HNO3 can be dissociated into NO2+ and OH- ion, why it 's called as proton donor (acid), i would called it as alkaline... can someone explain on this plaese?

I do not see how ##HNO_3## could act as a proton donor when clearly a stronger acid is present.
 
  • #3
You got the nitric acid dissociation into NO2+ wrong - OH- is not between products.

Hint: actually it is not HNO3 that dissociates into NO2+.
 
  • #4
Psst... hydroxide does not function well as a leaving group. So, why do you need the sulfuric acid for? Could it help create a good leaving group?
 
  • #5



HNO3, or nitric acid, is considered a proton donor because it can easily donate a proton (H+) to another molecule or compound. In the nitration of benzene, the HNO3 acts as an acid catalyst, meaning it donates a proton to the benzene ring, making it more reactive towards the electrophilic substitution reaction. The dissociation of HNO3 into NO2+ and OH- ions allows for the formation of a strong electrophile (NO2+) which can easily attack the benzene ring and initiate the nitration reaction. Therefore, in this context, HNO3 is considered a proton donor and an acid.
 

Related to Role of HNO3 in nitration of benzene

1. What is the role of HNO3 in the nitration of benzene?

HNO3, or nitric acid, is used as a reactant in the nitration of benzene. It helps to introduce a nitro group (-NO2) onto the benzene ring, resulting in the formation of nitrobenzene.

2. How does HNO3 facilitate the nitration of benzene?

HNO3 acts as a strong electrophile, meaning it is attracted to regions of high electron density. In the presence of a Lewis acid catalyst, such as H2SO4, HNO3 is protonated and its nitronium ion (NO2+) is formed. This nitronium ion is highly reactive and can attack the benzene ring, leading to the substitution of a hydrogen atom with a nitro group.

3. Can any other reagents be used in place of HNO3 for the nitration of benzene?

While HNO3 is the most commonly used reagent for the nitration of benzene, other nitrating agents such as nitrous acid (HNO2) or dinitrogen pentoxide (N2O5) can also be used. However, HNO3 is preferred due to its availability and efficiency in producing high yields of nitrobenzene.

4. What precautions should be taken when handling HNO3 in the nitration of benzene?

HNO3 is a corrosive and toxic chemical, and therefore appropriate safety measures should be taken when handling it. This includes wearing protective gear such as gloves, goggles, and a lab coat, and working in a well-ventilated area. It is also important to carefully follow proper storage and disposal procedures for HNO3.

5. What factors can affect the rate of nitration of benzene using HNO3?

The rate of nitration can be affected by several factors, including the concentration of HNO3, the temperature of the reaction, the presence of a catalyst, and the nature of the substituents on the benzene ring. For example, electron-donating substituents can increase the rate of nitration, while electron-withdrawing substituents can decrease it.

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