Journal of the American Chemical Society p. 1137 - 1145 (1981)
Update date:2022-09-26
Topics: Yield NMR spectroscopy Catalyst Reactants Reaction Conditions Substitution Reactions Gas Chromatography Experimental terms Direct substitution Alkanesulfonyl Derivatives Elimination-Addition Mechanisms Alkyl α-Disulfones
Fang, Lieh-pao O.
Kice, John L.
The reactions of a series of alkyl and aralkyl α-sulfones, RSO2SO2R ( R = Me, n-Bu, i-Pr, ArCH2) with a variety of nucleophiles in aqueous dioxane have been examined.Both rates of reaction and whether a given reaction takes place by an elimination-addition (sulfene intermediate) or a direct substitution (attack of nucleophile on SO2 group of α-sulphone) mechanism have been determined.The great majority of substitution reactions of alkyl α-disulfones take place via an elimination-addition mechanism (eq 3a), with formation of a sulphene from the α-disulphone being rate determining.Only when nucleophile is one, like azide ion, that is weakly basic while still being a good nucleophile is a direct substitution the preferred pathway.Even with azide the reaction pathway changes to elimination-addition when the acidity of the hydrogens on the carbon adjacent to the sulfonyl group is increased sufficiently, as in (PhCH2SO2)2.Comparison of rates of elimination of α-disulphones (R'CH2SO2)2 with rates of base-catalyzed hydrogen exchange of the corresponding trifluoromethyl sulfones R'CH2SO2CF3 indicates that formation of sulfenes from α-disulfones involves either an irreversible E1cB or a very E1cB-like E2 mechanism, a conclusion that is also supported by the observed variation of the rate of elimination of RR'CHSO2SO2R'' with changes in R and R'.Comparison of the behavior of an alkyl α-disulfone with that of the corresponding alkanesulfonyl chloride reveals that changing Y in RCH2SO2Y from RSO2 to Cl causes direct substitution to be able to compete much more effectively with elimination-addition.Kinetic studies show that this arises because, for a given nucleophile, (a) elimination-addition is 5-10 times slower for the alkanesulfonyl chloride than for the α-disulfone while (b) the rate of direct substitution is 5-10 times faster for the sulfonyl chloride.The origin of these rate differences is discussed and explained.
View MoreContact:0086-22-2822 1962 / 2822 1963
Address:B-808, No. 1, North-South Street, Hexi District,
puyang hongda shengdao new material co.,ltd.
Contact:+86-393- 4896278
Address:No.29 East Zhongyuan Road
Jinan Baozhao Pharmaceutical Co., Ltd
Contact:0086-531-86397156 82371858 82371868
Address:Huaneng Road, Jinan, Shandong ,China
Fuxin Jintelai Fluorin Chemical Co., Ltd.
Contact:+86-0418-8229599
Address:, 7th Huagong Road, Fluorine industry development zone (Yimatu Town,Fumeng County),Fuxin City, Liaoning Province, China
SHANDONG QINGYUNCHANGXIN CHEMICAL SCIENCE-TECH CO.,LTD
Contact:86-21-60560171
Address:1689Donghuan Rade,Qingyun County, Dezhou City, Shandong,China
Doi:10.1039/b209087m
(2003)Doi:10.1080/15421406.2017.1358013
(2017)Doi:10.1055/a-1146-2996
(2020)Doi:10.1016/S0031-9422(01)00293-X
(2001)Doi:10.1016/j.electacta.2017.06.151
(2017)Doi:10.1039/c5cc03429a
(2015)