Phenol is acidic in nature-phenol to salicylic acid and benzene change .

Why phenol is acidic in nature ?

The acidity of phenols  arises due to its ability to lose proton to form phenoxide ions. In case of  phenol molecule,  the –OH group  is directly attached to the sp2 hybridized carbon atom of aromatic phenyl ring .

Due to – R effect of phenyl ring , the lone pair electron on ‘O’-atom  takes part  in the resonance with the pi electron of benzene ring  .

As a result , the oxygen atom gets partially positive charge . Hence , oxygen atom attract the O – H  bonded electron towards itself .

Consequently, O –H bond becomes  more polar and easily break  to release proton in aqueous solution along with phenoxide anion .

Now this phenoxide ion formed is stabilized by the delocalization of negative charge due to the resonance with the pi electron of benzene ring.

It has been experimentally found that phenoxide ion has greater stability than phenols .

Because  in case of phenol charge separation takes place during resonance. But in case of phenoxide anion no such charge separation take place .

For the above two reason phenol is acidic in nature . The acidic properties of phenol is also supported by its pKa value .

The pKa value of phenol molecule is 9.98 . That is phenol is weak acid  .

Phenol to salicylic acid change

Phenol can be changed into salicylic acid by Reimer-Tiemann reaction . This is a chemical reaction in organic chemistry by which ortho hydroxyl benzaldehyde as well as ortho hydroxyl benzoic  acid (salicylic acid ) is obtained from phenol .

When the reaction is carried out in presence of  chloroform and  NaOH , the product is ortho hydroxyl benzaldehyde .

But if this reaction is  carried out in presence of carbon tetra chloride and NaOH base under 338 K – 348 K temperature , the product is ortho hydroxyl benzoic acid or salicylic acid .

In first step , the inter mediate product is  sodium 2-oxidobenzoate  which  on

hydrolysis by dilute HCl , the expected salicylic acid is produced . The reaction is shown below .

Phenol to benzene change

Phenol can be changed into benzene by reduction .  When phenol is heated  in the presence of strong reducing agent , it changed into benzene . 

Zinc metal ( dust ) is used as reducing agent . In this reaction , phenol reduced by Zn-metal and gets converted into benzene along with ZnO as side product 

The reaction of phenol to benzene changed is shown below .

Summary :

Why phenol is acidic in nature ?
Phenol to salicylic acid change
Phenol to benzene change 

What is Ditte's reaction in halogen chemistry-Click here .