371-69-7Relevant academic research and scientific papers
SOLVOLYSIS OF SOME ALKYL ESTERS OF FLUOROSULPHURIC ACID IN WATER AND AQUEOUS SOLVENTS
Cafferata, Lazaro F. R.,Desvard, Osvaldo E.,Sicre, Juan E.
, p. 940 - 943 (1981)
The solvolysis of methyl, ethyl, and, isopropyl fluorosulphates in pure water and aqueous organic solvents has been studied.The extrapolated reactivity at 25 deg C of these compounds is 1E4 to 1E6 times higher than that of halides, alkanesulphonates, and benzenesulphonates but is similar to that shown by chlorosulphates and perfluoroalkanesulphonates.The kinetics and medium and nucleophile effects have been investigated to establish the mechanism of the reactions.The effect of a variation in the dielectric constant of the medium has also been discused.The activation parameters of these solvolytic reactions were correlated through a ΔH vs. ΔS plot.It is concluded that even when methyl and ethyl fluorosulphates show behaviour typical of compounds reacting by a SN2-type mechanism, some evidence of a slight difference between both processes was found.The solvolysis of isopropyl fluorosulphate has a high contribution from a unimolecular ionization mechanism.
Pseudomolecular Rearrangement of O-Ethyl N-Methyl Toluene-4-sulphonimidate to N-Ethyl-N-methyltoluene-4-sulphonamide and its Relevance to the Nucleophilic Properties of Neutral Sulphonamides
Challis, Brian C.,Iley, James N.
, p. 699 - 704 (2007/10/02)
Kinetic studies are reported for the pseudo-molecular rearrangement of O-ethyl N-methyl toluene-4-sulphonimidate to N-ethyl-N-methyltoluene-4-sulphonamide in organic solvents at 34-100 deg C.Without catalysts, the rearrangement follows the equation rate = krearr 2, which is indicative of an intermolecular SN2 transalkylation via an ion-pair intermediate: it is accompained by concurrent E2 elimination to N-methyltoluene-4-sulphonamide.The rearrangement is catalysed by electrophilic reagents such as alkyl halides, ZnI2, and HBr where rate = k2 .For alkyl halides, a two-step mechanism via an ionic intermediate applies in which formation of the intermediate by an SN2 reaction between the substrate and alkyl halide is rate limiting.Other catalysts effect rearrangement by forming alkyl halides in an initial rapid reaction with the substrate.The results are discussed in relation to the ambident nucleophilic properties of sulphonamides.It is suggested that, like carboxylic acid amides and phosphinylamides, alkylation occurs most readily at the O-atom of neutral sulphonamides to give a sulphonimidate (kinetic product), which then rearranges in the presence of electrophilic catalysts to give an N-substituted sulphonamide (thermodynamic product).Rearrangement is normally too fast for the isolation of O-alkyl sulphonimidates, but O-aryl analogues can be obtained.
Formation and transformations of cations obtained from 1,1-dialkoxyalkanes in fluorosulfonic acid
Akhmatdinov, R. T.,Kantor, E. A.,Imashev, U. B.,Yasman, Ya. B.,Rakhmankulov, D. L.
, p. 626 - 630 (2007/10/02)
The reaction of 1,1-dialkoxyalkanes with fluorosulfonic acid at -75 deg C leads to the formation of alkoxycarbenium ions and protonated alcohols.The methoxy- and ethoxymethylcarbenium ions are stable at room temperature.Methoxycarbenium undergoes further reactions at -5 deg C.At -15 deg C ethoxycarbenium is converted by a 1,3-hydride shift into methoxymethylcarbenium.At this temperature the latter reacts with ethanol, forming ethoxymethylcarbenium and methanol.At -45 deg C isopropoxycarbenium is converted also by a 1,3-hydride shift into methoxydimethylcarbenium.Methyl, ethyl, and isopropyl alcohols are converted into the corresponding fluorosulfonic esters.
Betylates. 2. The formation and high reactivity of alkylbetylates
King, James Frederick,Lee, Teresa Mee-Ling
, p. 362 - 372 (2007/10/02)
Unhindered primary alkyl N,N-dimethylsulfamates (1) react with methyl fluorosulfate to give the corresponding alkyl fluorosulfates (3) and the betaine, Me3N(1+)SO3(1-) (4), evidently by way of the intermediate alkylbetylate fluorosulfate (2); with certain other alkyl esters (1) products of substitution, elimination, and rearrangement are formed.The reaction not only provides a potentially useful route to simple alkyl fluorosulfates, but serves to demonstrate the powerful nucleofugality of the betylate group.To obtain a method for predicting the reactivity of betylates, we have compared substituent parameters with rate constants in four series of nucleophilic displacement involving esters of the general structure ROSO2Z; correlation (of log k) with ?* is mediocre but a new parameter, ?15* with a "15percent resonance" contribution as defined by Swain and Lupton, gives good to excellent agreement in the four reaction series.Evidence is presented for formation of the 7-norbornyl cation via the betylate from 7-norbornyl N,N-dimethylsulfamate and methyl fluorosulfate.Comparison with what is known of the reactivities of 7-norbornyl p-toluenesulfonate and trifluoromethanesulfonate esters serves to confirm that betylates are among the most nucleofugal functions of which a derivative has been fully characterized.
