Alumina-Catalyzed Reactions of Hydroxyarenes and Hydroaromatic Ketones. 9. Reaction of Phenol with 1-Propanol

Article abstract of DOI:10.1021/jo01310a012

At 250-350 deg C in the presence of alumina, phenol (1) reacts with excess 1-propanol to give mainly (>90percent) C-alkylation to form mono- to penta-n-propylphenols plus some O-alkylations to form n-propyl aryl ethers. The principal component of the product mixture from 1 is 2,6-di-n-propylphenol (26-50 mol percent yield). With 4-n-propylphenol as substrate (instead of 1), tri-, tetra-, and penta-n-propylphenols are formed in 48-79percent combined yield. On the average, only 3percent of the total C3H7 groups in the product mixture are isopropyl ones. Deoxygenation is not observed. It is proposed that the principal products result from an S_N2-type reaction mechanism which involves nucleophilic attack (variously by C-2, C-4, C-6, or O) of an adsorbed ambident phenoxide ion onto C-1 of an adsorbed n-propoxide group. n-Propylation at C-3 and C-5 of the phenol ring results from surface-catalyzed dienone-phenol rearrangement.Isopropylation may occur via a side reaction of S_N1 type.