Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Cyclic sulfoxides and sulfones

TABLE 8. Estimated enthalpies of formation and ring correction values for cyclic sulfoxides and sulfones... [Pg.103]

In principle, the properties and chemical behavior of cyclic sulfoxides and sulfones having a ring size of seven and up are expected to be quite similar to those of the analogous acyclic systems. [Pg.471]

Several trends have emerged in the extensive carbon-13 NMR spectroscopy data that have been accumulated for sulfones and sulfoxides. Based on many studies of cyclic systems—particularly five- and six-membered ring sulfur compounds—these trends were shown to generally apply equally to both the cyclic and acyclic systems . Thus (a) oxidation of a sulfide to a sulfone results in a 20-25 ppm downfield chemical shift for sp -hybridized a-carbon atoms and 4-9 ppm upfield shift for / -carbons , and (b) there is very little difference between the chemical shifts of a-carbon atoms of sulfones and sulfoxides despite the difference in the inductive effects of these two functional groups . A difference is observed, however, in the H chemical shift of related cyclic sulfoxides and sulfones . [Pg.396]

Oxygen-17 NMR spectroscopy has an immense potential for structural analysis of cyclic sulfoxides and sulfones as well as for providing insight into the nature of bonding within these two functional groups . Indeed, in addition to data concerning the NMR chemical shifts for several cyclic sulfoxides and sulfones, NMR chemical shift differences between several diastereotopic sulfonyl oxygens in both cyclic and acyclic systems have been reported . [Pg.460]

Cyclic sulfoxides and sulfones ar best reated additively as oxides and dioxides, respectively (see p. 87). [Pg.133]

It is a stable, relatively inert, odorless compound melting at 218°C. It is insoluble in vi ater but mar Idc leadily crystallized from hot benzene, apor density measurements show tliat it is trimeric in the gaiseous state . On oxidation, trithiane is converted to cyclic sulfoxides and sulfones . [Pg.130]

It is illuminating to note that only very minor (and probably insignificant) differences can be detected as far as the r(SO) and sulfone groups in the thiirene series (i.e. I8a and 19a), compared with that of the acyclic analogues [i.e. (CH3)2SO and (CH3)2S02, respectively]. [Pg.389]

The less strain energy inherent in the four-membered ring sulfoxides and sulfones, their less distorted geometries and the lack of potential aromatic -type conjugation effects make the comparison of their physical and chemical properties with other cyclic and... [Pg.429]

In view of the limited capacity of the sulfur atom in the sulfoxide and sulfone functional groups to transmit conjugative effects due to the insulating effect of the LUMO sulfur d-orbitals45,46,56, the application of the UV technique even in the case of the cyclic vinyl sulfones (e.g. thiete dioxides 6b) cannot be expected to find extensive use. UV spectra of substituted thiete dioxides in which an extended conjugated system (e.g. 194) exists in the molecule, did provide useful information for structure elucidation231. However, the extent... [Pg.442]

Several typical reactions of cyclic sulfoxides or sulfones are not observed in the acyclic and large-ring sulfoxide and sulfone analogues, or if they are, they take a different path. In such cases the effect of the cyclic sulfoxide or sulfone function is at least partially a consequence of the particular stereochemical constraints of the cyclic array. [Pg.450]

Here, only few selected aspects associated with these systems, particularly those having generalizability and/or which provide a better understanding of the sulfoxide and sulfone functionality within cyclic systems (and/or not dealt with in References 280 and 281) will be... [Pg.459]

The distorted sp3 angles at both carbon and sulfur atoms in small ring sulfoxides and sulfones approach their normal size beginning with the thianes. Consequently, the characteristics and chemical behavior of six- and higher-membered sulfoxides and sulfones are expected to be similar to those of the acyclic counterparts. However, in view of the constraints imposed by the cyclic array, three issues deserve study ... [Pg.465]

The common route for the synthesis of medium-size ring sulfoxides and sulfones is oxidation of the corresponding cyclic sulfides70, which are obtained from the interaction of a, w-dihaloalkanes with sulfide ion in fair to good yields243 (equation 110). [Pg.472]

A few examples of hetero-Diels-Alder adducts have been reported [75-81]. A thio-chroman-fused fuUerene adduct was synthesized by the reaction of o-thioquinone with CgQ in o-dichlorobenzene at 180 °C [77]. The obtained cyclic sulfide 84 (Figure 4.4) can be oxidized to the corresponding sulfoxide and sulfone with m-chloroperoxybenzoic acid. Reaction of azadienes with Cgg leads to hetero Diels-Alder adducts such as, for example, 85 (Figure 4.4) [79]. The tetrahydropyrido[60]-fullerene 85 is formed in refluxing o-dichlorobenzene. [Pg.114]

The at complex from DIB AH and butyllithium is a selective reducing agent.16 It is used tor the 1,2-reduction of acyclic and cyclic enones. Esters and lactones are reduced at room temperature to alcohols, and at -78 C to alcohols and aldehydes. Acid chlorides are rapidly reduced with excess reagent at -78 C to alcohols, but a mixture of alcohols, aldehydes, and acid chlorides results from use of an equimolar amount of reagent at -78 C. Acid anhydrides are reduced at -78 C to alcohols and carboxylic acids. Carboxylic acids and both primary and secondary amides are inert at room temperature, whereas tertiary amides (as in the present case) are reduced between 0 C and room temperature to aldehydes. The at complex rapidly reduces primary alkyl, benzylic, and allylic bromides, while tertiary alkyl and aryl halides are inert. Epoxides are reduced exclusively to the more highly substituted alcohols. Disulfides lead to thiols, but both sulfoxides and sulfones are inert. Moreover, this at complex from DIBAH and butyllithium is able to reduce ketones selectively in the presence of esters. [Pg.170]

The applications of ruthenium tetroxide range from the common types of oxidations, such as those of alkenes, alcohols, and aldehydes to carboxylic acids [701, 774, 939, 940] of secondary alcohols to ketones [701, 940, 941] of aldehydes to acids (in poor yields) [940] of aromatic hydrocarbons to quinones [942, 943] or acids [701, 774, 941] and of sulfides to sulfoxides and sulfones [942], to specific ones like the oxidation of acetylenes to vicinal dicarbonyl compounds [9JS], of ethers to esters [940], of cyclic imines to lactams [944], and of lactams to imides [940]. [Pg.38]


See other pages where Cyclic sulfoxides and sulfones is mentioned: [Pg.385]    [Pg.460]    [Pg.385]    [Pg.454]    [Pg.74]    [Pg.385]    [Pg.460]    [Pg.385]    [Pg.454]    [Pg.74]    [Pg.139]    [Pg.95]    [Pg.392]    [Pg.396]    [Pg.441]    [Pg.444]    [Pg.875]    [Pg.95]    [Pg.389]    [Pg.392]    [Pg.441]    [Pg.444]    [Pg.875]    [Pg.58]    [Pg.139]    [Pg.139]    [Pg.52]    [Pg.156]    [Pg.391]    [Pg.58]    [Pg.437]   
See also in sourсe #XX -- [ Pg.133 ]




SEARCH



Cyclic sulfones

Sulfonate 7 and

Sulfonates cyclic

Sulfones sulfoxides

Sulfones, sulfoxides, sulfonates

Sulfonic cyclic

Sulfoxides and Sulfones

Sulfoxides cyclic

© 2024 chempedia.info