2.5- dihydrothiophene-l, 1-dioxides

Production. Sulfolane is produced domestically by the Phillips Chemical Company (Borger, Texas). Industrially, sulfolane is synthesized by hydrogenating 3-sulfolene [77-79-2] (2,5-dihydrothiophene-l,1-dioxide) (2), the reaction product of butadiene and sulfur dioxide ... 

Sulfolene (2,5-dihydrothiophene-l,1-dioxide) EK, MCB Isopropenyl acetate MCB Dimedon EK, MCB... 

The synthesis of N-phenyl-1,3,4,6-tetrahydrothieno(3,4-c)-pyrrole-2,2-dioxide (II) was carried out by reacting aniline with 3,4-bis(bromomethyl)-2,5-dihydrothiophene-l,1-dioxide (I). The latter compound was synthesized by the bromination of the cycloaddition product, prepared from 2,3-dimethyl-l,3-butadiene and sulfur dioxide (17). 

The reaction of o-halomethylene benzyl halides, l,4-dihalobut-2-enes, cyclo-2-hexenols or 2,5-dihydrothiophene-l,1-dioxides with Na2Fe(CO)4 or Fe2(CO)9 results in the formation of (diene)Fe(CO)3 complexes108. In each case, the precursor is transformed in situ into the free diene ligand, followed by complexation. 

Another example of type iii-a is the trifluoromethylation of double bonds by electrolysis of trifluoroacetic acid in the presence of olefins. Methyl vinyl ketone, vinyl acetate, diethyl fumarate, diethyl maleate, Ai-ethylmaleimide, and 2,5-dihydrothiophene-l,1-dioxide were examined as olefins. The products were bis-trifluoromethylated additive dimers (66) (type iii-a) and monomers (67) (type... 

R values were calculated from elemental analysis for carbon, hydrogen, and chlorine. It can be seen again that temperature has a very marked effect on composition. Even at 100°, however, about 16 mol% sulfur dioxide is present. There was also produced a small quantity (1 to 10% of the amount of copolymer) of the cyclic addition product, 3-chloro-2,5-dihydrothiophene-l,1-dioxide, m.p. 99-100°. 

The solvent-dependence of cheletropic reactions has also been investigated [158aj. The thermolysis of 3-methyl-2,5-dihydrothiophene-l,1-dioxide appears to involve a concerted fission of the two (T-bonds. This is in accordance with the very small solvent effect on rate observed in six solvents of different polarity [158a]. 

Reaction of 3,4-dimethylthiophene-1,1-dioxide with benzylthiolate at room temperature gives 3-benzylthiomethyl-4-methyl-2,5-dihydrothiophene-l,1-dioxide (208) in 86% yield. Again an exomethylene tautomer is implicated. A similar reaction takes place with iec-amines. With the 2,5-dimethyl isomer (202a), reaction with benzylthiolate is analogous to that with aqueous piperidine. 

This section consists of two parts (i) reactivity of 2,5-dihydrothiophenes and (ii) reactivity and applications of 2,5-dihydrothiophene-l,1-dioxides. 

Dimethylhutadiene sulfone (1,3-dimethylsulfolene, 2,4-dimethyl-2,5-dihydrothiophen-l,1-dioxide)... 

The cheletropic elimination reactions are widely used for generation of relatively unstable dienes in situ for Diels-Alder reactions. For example, extrusion of nitrogen from diazene 146, and sulfur dioxide from 2,5-dihydrothiophene-l,1-dioxide 147... 

Dihydrothiophenes are oxidized to 1,1-dioxides by m-chloroperoxybenzoic acid. These compounds are also accessible by (4 + 1)-cycloaddition of 1,3-dienes and sulfur dioxide. For instance, butadiene reacts even at room temperature with liquid sulfur dioxide to give an adduct 2,5-dihydrothiophene-l,1-dioxide, commonly known by the trivial name 3-suhnlene ... 

Shaikhrazieva et have reported cyclobutane adduct 41 formation from 2,5-dihydrothiophene-l,1-dioxide 40 and MA under the influence of... 

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