mechanism of prepartion of phenol from benzenesulphonic acid..?

(I) Preparation of benzene sulphonic acid:

(II) 

In this process, benzene sulfonic acid is reacted with aqueous sodium hydroxide. The resulting salt is mixed with solid sodium hydroxide and fused at a high temperature. The product of this reaction is sodium phenoxide, which is acidified with aqueous acid to yield phenol. This reaction is Nucleophilic Aromatic Substitution.