Reaction of phenol with sulphuric acid and nitric acid [closed]








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I'm confused a little bit about the products **A** and **B** .


[![link for the image](https://i.stack.imgur.com/kf8vl.jpg)](https://i.stack.imgur.com/kf8vl.jpg)


Please identify **A** and **B**




Actually, the reaction provided above is a better way to synthesize Picric acid(2,4,6-trinitrophenol).


First, when the phenol is reacted with concentrated $\ce{H2SO4}$ , it behaves like a normal sulphonation reaction at high temperatures. The major product at high temperature is **p-hydroxybenzenesulphonic acid**, although there is a small amount of o-hydroxy benzenesulphonic acid. So, you should write the **major product** in **A** which is **4-hydroxybenzenesulphonic acid**.


But, when **A** is treated with conc $\ce{HNO3}$, due to high activating property of $\ce{-OH}$ group, the $\ce{-NO2}$ groups are substituted at both the ortho positions.If both the ortho positions are substituted by $\ce{-NO2}$ group, there will be extensive intramolecular Hydrogen bonding , which makes this product thermodynamically very very stable ($\ce{$\Delta$H << 0)}$and at the higher temperatures the thermodynamically controlled product is formed in more amount.


More over, the $\ce{-NO2}$ groups also substitute the $\ce{-SO3H}$ groups at para position easily, because $\ce{H2SO4}$ being a stronger acid than $\ce{HNO3}$ ,the leaving $\ce{-SO3H}$ is more stable than $\ce{-NO2}$. So, the ultimate product gets all ortho-para positions of phenol substituted by $\ce{-NO2}$ groups.   
 So, **B** will be **PICRIC ACID(2,4,6 -trinitrophenol**)


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