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Sulfones, alkylation sulfur dioxide

A polysulfone is characterized by the presence of the sulfone group as part of its repeating unit. Polysulfones may be aUphatic or aromatic. AUphatic polysulfones (R and are alkyl groups) were synthesized by radical-induced copolymerization of olefins and sulfur dioxide and characterized many years ago. However, they never demonstrated significant practical utiUty due to their relatively unattractive physical properties, not withstanding the low cost of their raw materials (1,2). The polysulfones discussed in this article are those based on an aromatic backbone stmcture. The term polysulfones is used almost exclusively to denote aromatic polysulfones. [Pg.460]

Alkyl sulfonic acids are prepared by the oxidation of thiols (36,37). This reaction is not quite as simple as would initially appear, because the reaction does not readily go to completion. The use of strong oxidants can result in the complete oxidation of the thiol to carbon dioxide, water, and sulfur dioxide. [Pg.12]

Between sulfur dioxide radical anions, dithionite, and sulfoxylate/sulfite there exists a pH-dependent equilibrium465 (equation 86). Therefore, dithionite has been used as a source of sulfoxylate in order to prepare sulfinate and hence sulfones. Alkylation with triethyl oxonium fluoroborate leads to ethyl ethanesulfinate, alkyl iodides lead to symmetrical sulfones466 (equation 87). [Pg.216]

Sulfur dioxide (see above) as well as S02, SO , and SOj have been used as building blocks in three-component sulfone syntheses. It has long been known that aromatic sulfinic acids are easily available from diazonium salts and sulfur dioxide under copper catalysis . Mechanistically, aryl radicals as reactive intermediates add to sulfur dioxide generating arenesulfonyl radicals, which either take up an electron (or hydrogen) yielding a sulfinic acid or add to an olefinic double bond yielding final y -halogenated alkyl aryl sulfones (equation 78). [Pg.215]

The electrophilic character of sulfur dioxide does not only enable addition to reactive nucleophiles, but also to electrons forming sulfur dioxide radical anions which possess the requirements of a captodative" stabilization (equation 83). This electron transfer occurs electrochemically or chemically under Leuckart-Wallach conditions (formic acid/tertiary amine - , by reduction of sulfur dioxide with l-benzyl-1,4-dihydronicotinamide or with Rongalite The radical anion behaves as an efficient nucleophile and affords the generation of sulfones with alkyl halides " and Michael-acceptor olefins (equations 84 and 85). [Pg.216]

One of the major advantages of oxonium salts is that alkylations can be effected under reaction conditions that are generally much milder than those necessary with the more conventional alkyl halides or sulfonates. Triethyloxonium tetrafluoroborate, for example, has usually been employed at room temperature in dichloromethane or dichloroethane solution. Occasionally chloroform16-22 or no solvent at all4-20 is used. Difficult alkylations can be effected in refluxing dichloroethane.29 30 The less soluble trimethyloxonium tetrafluoroborate has been used as a suspension in dichloromethane or dichloroethane, or as a solution in nitromethane or liquid sulfur dioxide. Reports of alkylations in water23 and trifluoroacetic acid21 have also appeared. Direct fusion with trimethyloxonium tetrafluoroborate has succeeded in cases where other conditions have failed.25-30... [Pg.156]

The direct reaction of paraffinic petroleum fractions to alkyl sulfonates by the Reed process has been extensively investigated in this country. In this process paraffin-rich stocks are reacted with sulfur dioxide and chlorine (16) and processed to sulfonates as indicated by the equations ... [Pg.332]

Insertions of carbon dioxide, sulfur dioxide, and sulfur trioxide yield aluminum carboxylates, sulfinates, and sulfonates, respectively. Treatment of the resulting complexes with aqueous acid yields the corresponding aUcylcarboxylic, alkylsulphinic, and aUcylsulphonic acids. High pressure and temperatures of 220-240 °C are required for multiple insertions of CO2 to yield more than one equivalent of carboxyhc acid per aluminum. Excess aluminum trialkyl must be avoided or the initially formed carboxylate is completely alkylated to a trialkylcarbinol. Reaction of Ets A1 with CO2, for example, gives a 90% yield of triethylcarbinol. [Pg.154]

The importance of sulfones (R SO ) lies in the stabilization that they provide to adjacent carbanions. The carbanions are produced by treatment of the sulfone with a strong base such as butyl-lithium or lithium diethylamide. The sulfone a-carbanions may be alkylated and a variety of products may be formed. Once the sulfone has fulfilled its role in a synthetic sequence, it may be removed either by elimination as sulfur dioxide or by reductive cleavage using sodium amalgam. [Pg.51]

The sulfoxidation of alkanes to alkane sulfonic acids using a combination of sulfur dioxide and dioxygen and catalyzed by vanadium compounds has been reported [20]. The mechanism involves intermediacy of alkyl radicals which are trapped by sulfur dioxide and then further oxidized to the product. [Pg.1229]

Internal alkylation takes place on reaction of a-haloalkyl alkyl sulfones with bases and produces epi-sulfones as intermediaries. These intermediates are usually unstable and provide alkenes by thermal extrusion of sulfur dioxide. This reaction, known as the Ramberg-Backlund rearrangement, has been widely used in synthesis and has been thoroughly reviewed (Scheme 107, entry e).36-3. 43<.473... [Pg.163]

Detergents, which now rival soap in demand, are based largely on petroleum the variety of structures which confer detergent properties have led to some interesting syntheses. Alkyl aryl sulfonates are made by alkylation of benzene either with chlorinated kerosene or with a highly-branched olefin made from propylene. Long chain olefins for secondary sulfates were made from paraffin wax. Secondary alkyl sulfonates were made by direct sulfonation of paraffins with sulfur dioxide and chlorine, a reaction discovered in America in the 193O s. [Pg.324]

The theimolysis of 2-substituted 2,5-dihydrothiophene 1,1-dioxides leads to ( ) conjugated dienes via cycloieversion followed by the concerted cheletropic extrusion of sulfur dioxide. The thermolysis of the a, -alkylated sulfone (96) gives the intennediate, which loses SO2 to give 1-dodecadien-l-yl acetate (98), a component of the sex pheromone of the red bollwoim moth. Tliis procediue has been extended to the thermolysis of a,3-dialkylated sulfones in order to obtain ( , )-1,4-disubstituted-1,3-dienes (equation 46). Similar processes have been used for the syntheses of alkaloids. The synthesis of an Elaeocarpus alkaloid, elaeokwine A (100), makes use of the retrodiene extrusion of sulfur dioxide to give the 1,3-diene intermediate (99) that is subsequently consumed by an intramolecular imino DA reaction (equation 47). o-Xylylene (102) has been generated by rDA expulsion of SO2 from benzo-fiised 3,6-dihy(ho-l,2-oxathiin 2-oxide (101). ... [Pg.567]

The sulfone is a versatile functional group comparable to the carbonyl functionality in its ability to activate molecules for further bond construction, the main difference between these two groups being that the sulfone is usually removed once the synthetic objective is achieved. The removal most commonly involves a reductive desulfonylation process with either replacement of the sulfone by hydrogen (Eq. 1), or a process that results in the formation of a carbon-carbon multiple bond when a P-functionalized sulfone, for example a (3-hydroxy or (3-alkoxy sulfone, is employed (Eq. 2). These types of reactions are the Julia-Lythgoe or Julia-Paris-Kocienski olefination processes. Alkylative desulfonylation (substitution of the sulfone by an alkyl group, Eq. 3), oxidative desulfonylation (Eq. 4), and substitution of the sulfone by a nucleophile (nucleophilic displacement, Eq. 5) are also known. Finally, p-eliminations (Eq. 6) or sulfur dioxide extrusion processes (Eqs. 7, 8 and 9) have become very popular for the... [Pg.372]

By the interaction of sulfur dioxide and trialkyl alanes, when the A1—C bond is added across the S—0 bond, alkyl sulfinates of aluminum are obtained (231, 313). The analogous reaction with 3 moles of sulfur trioxide leads to alkyl sulfonates (19) ... [Pg.329]

Thennal decomposition of spent sulfuric acids to give sulfur dioxide is achieved in a furnace at temperatures around 1,000 °C. Spent acids come from processes where H2SO4 or oleum is used as a catalyst (alkylation, nitration, sulfonation, etc.) or from other processes where H2SO4 is used to clean, dry, and remove water. [Pg.15]

The second recent variant, developed by Julia and co-workers, avoids reductive elimination altogether and provides a remarkable one-pot connective synthesis of alkenes. The procedure, illustrated in eq 14, involves condensation of an aldehyde or ketone with a lithiated benzothiazolyl alkyl sulfone to give an adduct which first cyclizes and then fragments with extrusion of sulfur dioxide, benzothiazolone (which then tautomerizes to 2-hydroxybenzothiazole), and the alkene. Generally a mixture of ( )- and (2)-alkenes is obtained, hut in stericaUy hindered substrates the ( ) isomer can be obtained selectively. The same reaction has been observed with the pyridinyl sulfone analogs, in which case the separable /8-hydroxy sulfone intermediates undergo stereospecific and elimination to the corresponding alkene. [Pg.442]


See other pages where Sulfones, alkylation sulfur dioxide is mentioned: [Pg.323]    [Pg.215]    [Pg.216]    [Pg.694]    [Pg.1098]    [Pg.694]    [Pg.1098]    [Pg.431]    [Pg.891]    [Pg.987]    [Pg.891]    [Pg.177]    [Pg.521]    [Pg.987]    [Pg.567]    [Pg.4510]    [Pg.713]    [Pg.351]    [Pg.445]    [Pg.715]    [Pg.23]    [Pg.696]    [Pg.1530]    [Pg.78]    [Pg.71]    [Pg.324]    [Pg.149]    [Pg.225]   
See also in sourсe #XX -- [ Pg.1537 ]




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