118795-68-9Relevant academic research and scientific papers
Reactions of sulfur trioxide with benzene derivatives containing a deactivating oxy substituent
Ansink, Harold R. W.,Cerfontain, Hans
, p. 215 - 221 (2007/10/02)
The reactions of phenyl acetate (2), (trifluoromethoxy)benzene (3), (difluoromethoxy)benzene (4), 4-(trifluoromethoxy)phenol (5), 4-(trifluoromethoxy)phenyl methanesulfonate (6), 4-(trifluoromethoxy)anisole (7) and 3-(trifluoromethoxy)anisole (8) with SO3 in nitromethane have been studied.Upon reaction with SO3, 2 yields 2-4-sulfonic acid (2-4-S); subsequently, transfer of the acetyl group takes place to yield the mixed anhydride of phenol-4-pyrosulfonic acid and acetic acid (9) or the corresponding hydrogen sulfate 10, depending on the amount of SO3 used.Reaction of the α-fluorinated anisoles 3 and 4 with SO3 leads to sulfonation at the 4-position only; however, on using both a high substrate concentration and an excess of SO3, some 2,4-S2 is formed with 4 but not with 3.On reaction of 5 with 0.8 mol-equiv of SO3 in C(2)H3NO2, the hydrogen sulfate derivative (5-O-S) is formed; at 100 deg C, some isomerization to 5-2-S occurs.Upon reaction with 4.0 mol-equiv of SO3, the initially formed hydrogen sulfate slowly yields the corresponding 2-sulfophenyl hydrogen sulfate (5-O,2-S2).On using 6.0 mol-equiv of SO3, the 5-O,2-S2 is slowly converted into 6-(trifluoromethoxy)benzo-1,3,2,4-dioxadithiin 2,2,4,4-tetraoxide (11).Reaction of 6 with either 0.9 or 3.0 mol-equiv of SO3, initially leads to insertion of sulfur trioxide in between the SO2CH3 and the adjacent O, yielding the 4-(trifluoromethoxy)phenyl methanepyrosulfonate 12.This species subsequently yields 13 and 14.Reaction of 7 with SO3 leads to sulfonation only at the 2-position; eventually some sulfodemethylation to yield 5-2-S takes place.Reaction of 8 with 1.0 mol-equiv of SO3 yields a 68:32 mixture of 8-4-S and 8-6-S.
Sulfonation of three Symmetrical 2,6-Dialkylphenols, 2,6-Dichlorophenol, Phenol, and 2,6-Dimethylanisole. Sulfation and Sulfonation Product Distribution and Mechanisms
Cerfontain, Hans,Koeberg-Telder, Ankie,Lambrechts, Hans J.A.,de Wit, Peter
, p. 4917 - 4923 (2007/10/02)
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.
