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Aryl-sulfur bond

Under the same conditions (LDDB in THF, — 78°C) the reductive lithiation step occurred immediately for seven- and eight-membered rings. With a five-membered ring, cleavage of the aryl-sulfur bond was observed and phenyllithium produced. [Pg.160]

Dihydrobenzo[b]thiophene 1,1-dioxide undergoes electrochemical cleavage of the aryl-sulfur bond,21 to give the sulfinate anion,... [Pg.197]

Walling and Rabinowitz observed (299,300) that, in the presence of appropriate initiators, trialkyl phosphites can undergo a free radical chain reaction with alkyl disulfides to yield an 0,0,0-trialkyl phosphorothioate and an alkyl sulfide (eq. 11a). Because of the strength of the aryl-sulfur bond in phenyl disulfide, an ethyl rather than an aryl radical would be eliminated from the radical intermediate (eq. 11b) in this instance. [Pg.82]

At present, it appears that the best way to form aryl-sulfur bonds is the recently developed metal-catalyzed ronte from aryl halides [210,211] this method appears to be more versatile than the photochemical methods. The latter ones are in practice limited to the reaction, a procednre that is seriously limited by the concurrent fragmentation of the radical anion intermediate as discussed above. [Pg.162]

Sulfonic acids are prone to reduction with iodine [7553-56-2] in the presence of triphenylphosphine [603-35-0] to produce the corresponding iodides. This type of reduction is also facile with alkyl sulfonates (16). Aromatic sulfonic acids may also be reduced electrochemicaHy to give the parent arene. However, sulfonic acids, when reduced with iodine and phosphoms [7723-14-0] produce thiols (qv). Amination of sulfonates has also been reported, in which the carbon—sulfur bond is cleaved (17). Ortho-Hthiation of sulfonic acid lithium salts has proven to be a useful technique for organic syntheses, but has Httie commercial importance. Optically active sulfonates have been used in asymmetric syntheses to selectively O-alkylate alcohols and phenols, typically on a laboratory scale. Aromatic sulfonates are cleaved, ie, desulfonated, by uv radiation to give the parent aromatic compound and a coupling product of the aromatic compound, as shown, where Ar represents an aryl group (18). [Pg.96]

Carbon-sulfur bonds can be formed by the reaction of elemental sulfur with a lithio derivative, as illustrated by the preparation of thiophene-2-thiol (201) (700S(50)104). If dialkyl or diaryl disulfides are used as reagents to introduce sulfur, then alkyl or aryl sulfides are formed sulfinic acids are available by reaction of lithium derivatives with sulfur dioxide. [Pg.80]

Salts of mono-alkylated or arylated sulfur diimide anion [RNSN] (R = aryl, Bu, SiMcs) are prepared by Si-N cleavage of RNSNSiMcs with [(Me2N)3S][Mc3SiF2]. ° ° These anions adopt cis configurations with very short terminal S-N bond lengths (1.44 - 1.49 A) indicative of a thiazylamide anion, [RNS N] (5.21). ... [Pg.99]

The acid cleavage of the aryl— silicon bond (desilylation), which provides a measure of the reactivity of the aromatic carbon of the bond, has been applied to 2- and 3-thienyl trimethylsilane, It was found that the 2-isomer reacted only 43.5 times faster than the 3-isomer and 5000 times faster than the phenyl compound at 50,2°C in acetic acid containing aqueous sulfuric acid. The results so far are consistent with the relative reactivities of thiophene upon detritia-tion if a linear free-energy relationship between the substituent effect in detritiation and desilylation is assumed, as the p-methyl group activates about 240 (200-300) times in detritiation with aqueous sulfuric acid and about 18 times in desilylation. A direct experimental comparison of the difference between benzene and thiophene in detritiation has not been carried out, but it may be mentioned that even in 80.7% sulfuric acid, benzene is detritiated about 600 times slower than 2-tritiothiophene. The aforementioned consideration makes it probable that under similar conditions the ratio of the rates of detritiation of thiophene and benzene is larger than in the desilylation. A still larger difference in reactivity between the 2-position of thiophene and benzene has been found for acetoxymercuration which... [Pg.44]

Chiral sulfoxides with at least one sulfur-bonded aryl group have been separated by liquid chromatography into the enantiomers26. Some of the columns employed, which are commercially available, used 3,5-dinitrobenzoyl)phenylglycine bonded to silica... [Pg.58]

These investigators also observed that cleavage of the carbon-sulfur bond of aryl sulfones, a very difficult process to carry out by other means, proceeds smoothly at a mercury electrode even with sterically hindered sulfones, although the direction of cleavage of the latter appears to be governed by steric considerations, e.g. 11 >,... [Pg.27]

Several studies have been performed on the photodecomposition of diaryl sulfones and polysulfones Khodair, et. al., (21) demonstrated that the photodecomposition of diaryl sulfones proceeds by a free-radical mechanism with initial carbon-sulfur bond cleavage. This gives an aryl radical and an aromatic sulfonyl radical. The latter radical can react with oxygen and a hydrogen donor to eventually form the hydroxyl radical. The hydroxy radical may attack the aromatic nucleus in PET and forms the hydroxyterephthaloyl radical. [Pg.259]

A palladium-catalyzed protocol for carbon-sulfur bond formation between an aryl triflate and para-methoxybenzylthiol was introduced by Macmillan and Anderson (Scheme 6.66) [138], Using palladium(II) acetate as a palladium source and 2,2 -bis(diphenylphosphino)-l,l -binaphthyl (BINAP) as a ligand, microwave heating of the two starting materials in N,N-dimethylformamide at 150 °C for 20 min in the presence of triethylamine base led to the formation of the desired sulfide in 85% yield. [Pg.153]

Acyclic alkyl phenyl sulfones undergo an alkyl-sulfur bond cleavage [123] however, in cyclic arylsulfones the aryl-sulfur... [Pg.414]

Isothiocyanates add carbodiimides across the carbon-sulfur bond (Scheme 28). The reaction works best for aryl isothiocyanates with electron-withdrawing groups (75JCS(P2)1475). [Pg.568]

The nickel-catalysed reaction of aryl, allyl or vinyl sulfides with Grignard reagents has been found to be an effective way for the conversion of carbon-sulfur bonds into carbon-carbon bonds [318]. However, simple aliphatic substrates are inert. [Pg.53]


See other pages where Aryl-sulfur bond is mentioned: [Pg.84]    [Pg.84]    [Pg.103]    [Pg.124]    [Pg.715]    [Pg.285]    [Pg.84]    [Pg.84]    [Pg.103]    [Pg.124]    [Pg.715]    [Pg.285]    [Pg.443]    [Pg.174]    [Pg.6]    [Pg.7]    [Pg.876]    [Pg.1101]    [Pg.58]    [Pg.876]    [Pg.1101]    [Pg.151]    [Pg.233]    [Pg.316]    [Pg.79]    [Pg.425]    [Pg.89]    [Pg.30]    [Pg.85]    [Pg.174]    [Pg.475]    [Pg.119]    [Pg.174]    [Pg.475]   
See also in sourсe #XX -- [ Pg.285 ]




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Aryl Bonds

Aryl-sulfur bond formation

Bonding aryls

Sulfur bonding

Sulfur bonds

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