Acid-catalyzed transfer sulfonation of anisole using overcrowded polymethylbenzenesulfonic acids

✍ Scribed by Ankie Koeberg-Telder; Hans Cerfontain

• Book ID: 104589135
• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 374 KB
• Volume: 109
• Category: Article
• ISSN: 0165-0513
• DOI: 10.1002/recl.19901090203

✦ Synopsis

Abstract

Transfer sulfonations of anisole using various polymethylbenzenesulfonic acids (PoMBR's) catalyzed by trifluoromethanesulfonic acid at 25 °C are described. The observed reactivity order for transfer sulfonation increases in the order 2,4‐DiMBS, 2,6‐DiMBS, 2,3,4,5‐TeMBS (all non‐reactive) < 2,3,5,6‐TeMBS ≈︁ 2,4,6‐TrMBS < 2,3,4,6‐TeMBS < PeMBS. This order illustrates that the main factor in determining the transfer sulfonation reactivity is ‐ in addition to the electronic activation by the 4‐methyl ‐ the degree of overcrowding around the sulfonic acid group of the PoMBS. A mechanism is suggested in which the essential step involves the transfer of SO~3~H^+^ from the 1‐arenonium‐1‐sulfonic acid ion to the anisole.