Additions of sulfur trioxide

The only stable 1,3,2-dioxathietanes known are fluorinated sulfate derivatives formed by addition of sulfur trioxide to bis(trifluoromethyl)ketene. These structures are fairly well characterized from spectral data and from reactions with nucleophiles. Hexafluoroisopropy-lidene-l,3,2-dioxathietane 2,2-dioxide acts as a sulfur trioxide transfer agent to alkenes and is in equilibrium with a dimeric form as indicated by 19F NMR (Scheme 138) (71KGS1645, 72KGS306, 73KGS178, 132l). 

The /J-sultones 3 are readily formed by the addition of sulfur trioxide to polyfluorinated al-kenes.45,46 They are the building blocks of DuPont s Nation membranes.52 Possible mechanisms for the rearrangement have been proposed,45,46,53,54 which all involve initial attack of the nucleophile at the sulfur atom with ring opening at the S-O bond. 

An alternative mechanism, which operates either in 100%, or in fuming sulfuric acid (which contains dissolved S03), is addition of sulfur trioxide to the OH group ... 

Oxathiin 2,2-dioxides (sultones) (e.g., 150) are obtained by the addition of sulfur trioxide to dienes or by ringclosing metathesis (RCM) of sulfonates using the second-generation Grubbs ruthenium catalyst (Scheme 75) . The same catalyst was also successfully employed in the RCM of diallyl disulfide 151 which led quantitatively to 3,6-dihydro-l,2-dithiin 152 (Scheme 76) <20020L1767>. 

A reaction closely related to the [2 + 2] cycloaddition of thiocarbonyl S.S-dioxides is the addition of sulfur trioxide-dioxane complex to alkenes. This occurs stereoselectively and from (Z)- and (E)-2-butene the corresponding cis- and /ra .s -3,4-dimethyl-1,2-oxathietane 1,1-dioxides 11 are obtained121. 

Oxathietane 2,2-dioxides (e.g., 448) are isolated in good yields from the reaction of sulfur trioxide with fluorinated alkenes, fluorinated dienes, ° and from the reaction of the sulfur trioxide donor 499 with fluorinated alkenes. Zwitterionic intermediates ( C-C-S020 ) are suggested. An explosion has been reported in the addition of sulfur trioxide to tetrafluoro-ethylene. Tetrafluoroethane /3-sultone (498) also is obtained by treatment of fluorosulfonyldifluoroacetic anhydride with antimony trichloride. ... 

Boron trifluoride-triethylamine effects a ring-opening elimination of 4,4-difluoro-3-trifluoromethyl-l,2-oxathietane 2,2-dioxide to give fluorosulfonyl-trifluoromethylketene. Eliminations occur from intermediate 3-sultones, obtained by addition of sulfur trioxide to alkenes, to give alkenesulfonic acids. ... 

Trichloromethyl-l,2-oxathietane 2,2-dioxide is a catalyst for the acylation of alcohols and amines under mild conditions.It also catalyzes the polymerization of (NPCl2)3. It is suggested that six-membered cyclic sultones are derived from /3-sultones transiently formed in the addition of sulfur trioxide to alkenes. Ring-expansion of 3,4,4-trifluoro-3-trifluorovinyl-l, 2-oxathietane 1-oxide occurs at 100°C to give 4,4,5,6,7,7-hexafluoro-l,3-dioxa-2-thiacyclohept-5-Halogenation of 3,3,4,4-tetrafluoro-l,2-oxathietane 2,2-dioxide in... 

The intermediate 3-sultone 508, obtained by addition of sulfur trioxide to l-ethoxy-l-trifluoromethyl-2,2-difluoroethylene, decomposes to a 3-ketosulfonate ester. A similar reaction is observed with 4-(l,2-dibromo-l,2,2-trifluoroethyl)-... 

Derivatives of S2N2 in which hexavalent sulfur is involved have been obtained by addition of sulfur trioxide to A sulfinylsulfonamides (e-g-, to give 613) and by the reaction of sulfur triamides with perfluoroalkylisocyanates (e.g., to give 608) or 7V-sulfmyl amines. ... 

For this reason an excess of 30-40 per cent or more than the calculated amount of sulfuric acid is used. Increase in the rate of sulfonation is obtained by the addition of sulfur trioxide to sulfuric acid. Ordinary concentrated sulfuric acid contains about 96-98 per cent H2SO4, the rest of the liquid being water. Sufficient sulfur trioxide can be added to convert this water to sulfuric acid and thus obtain 100 per cent acid. Addition of still more sulfur trioxide... 

A large number of sulfamate esters can be prepared by addition of an activated electrophile across an alkene carbon-carbon double bond. The activated electrophiles are formed by addition of sulfur trioxide to dialkylchloramines like... 

The formation of the sultone (160) probably involves addition of the complex across the alkene double bond, a 1,2-hydride shift and an intramolecular nucleophilic substitution reaction. The sultone (161) is formed by addition of sulfur trioxide to give the unstable p-sultone which rearranges to the more stable y-isomer (161). Another useful route to sultones is by metallation of alkanesulfonate esters for example, butane-1,3-dimethylsulfonate (162), prepared from butanel,3-diol, yields the 8-sultone, namely 6-methyl-l,2-oxathiin-2,2-dioxide (163) (Scheme 67). 

Regeneration of high concentrations of sulfuric acid may also be achieved by addition of oleum or sulfur trioxide to diluted acid. The inventory of acid in circulation is increased by a corresponding amount (Eq. 9.26). A third method of reconcentration, useful when the acid consumption occurs as a part of, or adjacent to a contact sulfuric acid plant, is to pass the diluted acid itself through the acid plant absorption tower. This amounts to on-site addition of sulfur trioxide, and the increased acid inventory obtained can be sold to markets through the normal producer channels. 

ADDITION OF SULFUR TRIOXIDE TO PENTAFLUOROTHIO (SFj) (PENTAFLUORO- i -SULFANYL) CONTAINING FLUOROOLEFINS... 

Dmitriev, M.A. Sokol skii, G.A. Knunyants, I.L. Addition of sulfur trioxide to fluoro olefins. Khim. Nauka i Prom. 1958, 3, 826-828. 

During the addition of sulfur trioxide to the carbon tetrachloride no appreciable rise in temperature is observed and very little, if any, evolution of phosgene occurs. When... 

SMEs are prepared by the addition of sulfur trioxide to the alpha carbon of a methyl ester and subsequent neutralization with a base. Two surfactant moieties are formed (see Fig. 1). The primary surfactant formed is SME. The secondary surfactant formed is a sulfonated fatty acid. This molecule contains two different acid groups, a sulfonic acid and a carboxylic acid group. At a pH of roughly 4.5 to 9 the sulfonated fatty acid is present as a mixture of monoanion and dianion [1]. Below pH 4, the diacid is present as a monoanion. At pH < 9, the sulfonated fatty acid is present in a disodium salt form. 

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