Name the different reagents needed to perform the following reaction:

(i) Phenol to benzene

(ii) Dehydration of propan-2-ol to propene.

(iii) Friedel Craft’s acetylation of anisole.

(iv) Dehydrogenation of ethanol to ethanal

(i) Zinc dust is used to reduce phenol to benzene while gets oxidised to ZnO. Zinc is strong reducing agent.

(ii) Strong heating in presence of concentrated sulphuric acid or phosphoric acid.

Acids supply H⁺ ions which get protonated on the oxygen of –OH to form –O⁺H₂. Since positive charge on oxygen( as it is electronegative in nature) is not stable the C-O⁺H₂ breaks to give alkene and water molecules.

(iii) Anhydrous AlCl₃ and acyloxy chloride(RCOCl)

AlCl₃ is a Lewis acid which accepts Cl^- from RCOCl to give AlCl₄^- and RCO⁺ which easily undergoes electrophilic substitution reaction with anisole.

(iv) Sodium or potassium dichromate in presence of dilute sulphuric acid.

This gives chromic acid reacts with alcohol to give chromic ester. This further breaks down to give aldehyde.