Q.Give the equations of the reactions for the preparation of phenol from isopropyl benzene.

Step 1. Identify the starting material. Isopropylbenzene is cumene, C6H5-CH(CH3)2 -- a benzene ring bearing an isopropyl group, the commercial starting material for the industrial phenol process (section 11.4.2).

Step 2. First equation -- air oxidation. Cumene is oxidised by atmospheric oxygen (O2) at 423 K, in the presence of a cobalt-naphthenate catalyst, at the isopropyl group's tertiary C-H bond, to give cumene hydroperoxide: C6H5-CH(CH3)2 + O2 --Co-naphthenate, 423K--> C6H5-C(CH3)2-O-O-H.

Step 3. Second equation -- acid decomposition. Cumene hydroperoxide is then decomposed by treatment with dilute HCl (with heating): the O-O bond breaks, and the molecule rearranges and fragments to give phenol as the aromatic product, with acetone released simultaneously as a valuable co-product: C6H5-C(CH3)2-O-O-H --dil. HCl, heat--> C6H5-OH + (CH3)2C=O. …

Writing out the two-step cumene process exactly as given in section 11.4.2: air oxidation to the hydroperoxide …

• Omitting acetone as a co-product, which the chapter specifically flags as commercially valuable and part of the reaction's economic significance. …