Nowadays picric acid is prepared by treating phenol with concentrated Sulphuric acid which converts it into phenol - 2,4 - disulphonic acid, and then with concentrated nitric acid to get 2,4,6 - trinitrophenol. Can you write the equations of reaction involved?

Certainly! The synthesis of picric acid (2,4,6-trinitrophenol) involves two steps. First, phenol is treated with concentrated sulfuric acid to form phenol-2,4-disulfonic acid. Then, this intermediate is treated with concentrated nitric acid to produce picric acid. Here are the balanced chemical equations for the reactions:

Formation of Phenol-2,4-disulfonic acid:
C
6
H
5
OH
+
2
H
2
SO
4
→
C
6
H
3
(OH-SO
3
H)
2
+
2
H
2
O
C
6
​
H
5
​
OH+2H
2
​
SO
4
​

​
C
6
​
H
3
​
(OH-SO
3
​
H)
2
​
+2H
2
​
O

This reaction involves the sulfonation of phenol.

Formation of Picric Acid (2,4,6-Trinitrophenol):
C
6
H
3
(OH-SO
3
H)
2
+
3
HNO
3
→
C
6
H
2
(NO
2
)
3
OH
+
3
H
2
SO
4
+
3
H
2
O
C
6
​
H
3
​
(OH-SO
3
​
H)
2
​
+3HNO
3
​

​
C
6
​
H
2
​
(NO
2
​
)
3
​
OH+3H
2
​
SO
4
​
+3H
2
​
O

This reaction involves the nitration of the intermediate phenol-2,4-disulfonic acid to produce picric acid.