Journal of Organic Chemistry p. 4917 - 4923 (1984)
Update date:2022-08-03
Topics:
Cerfontain, Hans
Koeberg-Telder, Ankie
Lambrechts, Hans J.A.
de Wit, Peter
The sulfonation of four symmetrically substituted 2,6-disubstituted phenols, phenol, 2,6-dimethylanisole with SO3 in aprotic solvents was studied.With the phenols the initial product is the phenyl hydrogen sulfate, which is slowly converted into the phenolsulfonic acids via O-desulfonation and subsequent C-sulfonation if the phenol is in excess and via C-sulfonation and subsequent O-desulfonation if the SO3 is in excess.The ratio of partial rate factors for 3- and 4-sulfonation (f3/f4) for 2,6-dimethylphenol (1) in nitromethan strongly decreases on replacing the methyl groups by i-Pr, t-Bu (steric effects), and Cl (electronic effects).The strong increase of f3/f4 on increasing the SO3:1 ratio from 0.9 to 6.0 is ascribed to increasing sulfonation of the phenyl hydrogensulfate for which because of steric inhibition of resonance f3/f4 is higher (3.9) than that of the phenol 1 (<0.01) and of 2,6-dimethylanisole (5) (<0.01).The protic sulfonation of 1 and 5 in concentrated sulfuric acid was also studied.The large variations in f3/f4 with increasing sulfuric acid concentration are discussed in terms of steric inhibition of resonance for the entities undergoing sulfonation, viz., 1, its hydrogen sulfate, and 5 by the various sulfonating entities in the sulfuric acid range 75 - 107 percent H2SO4.
View MoreSuzhou Credit International Trading Co., Ltd
Contact:+86-512-65398039
Address:Qingdeng, Hightech. District, Suzhou
Contact:+91 - 22 - 26355700
Address:17, Lotus Business Park, Andheri West
puyang hongda shengdao new material co.,ltd.
Contact:+86-393- 4896278
Address:No.29 East Zhongyuan Road
website:http://www.orchid-chem.com
Contact:+86-571-85395792
Address:607, North Zhongshan Road, Hangzhou 310000 China
Hangzhou Gangjin Chemical Co.,Ltd.
Contact:+86-571-85109780
Address:707 Zhejiang Minhang Bldg., No.290 Zhongshan North Road, Hangzhou 310003, China
Doi:10.1016/j.cclet.2012.01.042
(2012)Doi:10.1016/j.tet.2012.01.093
(2012)Doi:10.1021/om300051f
(2012)Doi:10.1016/j.tetlet.2012.02.014
(2012)Doi:10.1055/s-1991-26555
(1991)Doi:10.1021/ja01133a514
(1952)