Thiolate ions salts

Thioethers (sulfides) can be prepared by treatment of alkyl halides with salts of thiols (thiolate ions). The R group may be alkyl or aryl and organolithium bases can be used to deprotonate the thiol. As in 10-37, RX cannot be a tertiary halide, and sulfuric and sulfonic esters can be used instead of halides. As in the Williamson... 

Reaction bewteen diazonium salts and thiolate ions or Na2S... 

Thioethers (sulfides) can be prepared by treatment of alkyl halides with salts of thiols (thiolate ions).7S2 R may be alkyl or aryl. As in 0-35, RX cannot be a tertiary halide, and sulfuric and sulfonic esters can be used instead of halides. As in the Williamson reaction (0-12), yields are improved by phase-transfer catalysis.753 Instead of RS ions, thiols themselves can be used, if the reaction is run in benzene in the presence of DBU (p. 1023).754 Neopentyl bromide was converted to Me3CCH2SPh in good yield by treatment with PhS in liquid NH3 at -33°C under the influence of light.755 This probably takes place by an SrnI mechanism (see p. 648). Vinylic sulfides can be prepared by treating vinylic bromides with PhS in the presence of a nickel complex,756 and with R3SnPh in the presence of Pd(PPh3)4.757 R can be tertiary if an alcohol is the substrate, e.g,758... 

Thiolate ions are also useful for the demethylation of certain ethers,761 esters, amines, and quaternary ammonium salts. Aryl methyl ethers762 can be cleaved by heating with EtS... 

The chemical shifts (downfield from 85% HoPO ) of sulfonium salts ]X with various Y are very close (a) 5 = +86.1 ppm (temp. 55°C), (b) 6 = +90.1 ppm, (c) 6 = +86.8 ppm, (d) 6 = +86.7 ppm, (e) 6 = +89.2 ppm, (f) 6 = +92.2 ppm. This suggests that all these salts have "true" sulfonium structure with little interaction within the ion pair involved. It is of interest to note that J X (X = Y = Br) reacts with cyclohexene to give 1,2-dibromo-cyclohexane and the starting thiolate. Sulfonium salts J X react readily with external nucleophiles of high P-nucleophi1icity e.g. water and alcohols. The reaction between l (R = Bu1, R = Ph,... 

Thiol sulfide mercapto group alkylthio group disulfide thiolate ion trialkylsulfonium salt sulfoxide sulfone... 

Thiolate ions react with a-(alkylthio)carbonyl compounds to afford disulfides and the corresponding reduced ketone (equation 26). The reaction apparently involves direct nucleophilic attack by thiolate on the sulfur atom of the alkylthio group. Other soft bases, such as cyanide ion, thiourea and tertiary phosphines, also effect this conversion. Raney nickel of course readily desulfurizes a-alkylthiocarbonyl compounds. The reaction is quite selective for example, the ester, ketone and alkenic moieties of (43) are unaffected by the Raney nickel treatment (equation 27). Raney nickel reduction of (44) is reported to proceed with retention of configuration in ethanol and with inversion in acetone. Telluride salts also desulfurize a-alkylthio ketones. ... 

Thiolate ions are also useful for the demethylation of certain ethers, esters, amines, and quaternary ammonium salts. Aryl methyl ethers can be cleaved by heating with EtS in the dipolar aprotic solvent DMF ROAr + EtS ArO +EtSR. Carboxylic esters and lactones are cleaved (the lactones give co-alkylthio carboxylic acids) with a thiol and AICI3 or AlBrs. Esters and lactones... 

A wide range of nucleophilic substrates of different reactivity were trifluoromethylated with these reagents. The substrates include carbanions, activated aromatics, heteroaromatics, enol silyl ethers, enamines, phosphines, thiolate ions and iodide anions. " (Scheme 3.8) The least reactive substrates, such as triphenylphosphine, aniline and phenols, require the use of the most reactive dinitro derivative. Most of the reactions can be conveniently performed with the unsubstituted 5-trifluoromethyl dibenzothiophenium salt (35). The least reactive sulfonium salts are the acyclic sulfonium compounds which reacted only with the sodium thiolates.55,59... 

Thiols are sulfur analogs of alcohols. They are stronger acids and have lower boiling points than alcohols. Thiolate ions are weaker bases and better nucleophiles in protic solvents than alkoxide ions. Sulfur analogs of ethers are called sulfides or thioethers. Sulfides react with alkyl halides to form sulfonium salts. 

In the initial demonstration of this concept, the aryl radical was obtained by the classic tin method (eq 2). Subsequently, by changing the radical precursor from a halogen to a diazonium ion and working in the presence of an appropriate source of electrons, it was possible to carry out the homolytic displacement reaction under stannane-free, nonreductive conditions. The method is based on work from the Beckwith laboratory, in which it was demonstrated that arenediazonium salts in the presence of electron donors, such as iodide and thiolate ions, can generate aryl radicals in a facile, clean reaction. 

The tricyclic sulphides (11) were formed by intramolecular opening of an epoxide by a thiolate ion that was generated in situ. The precursors (12) were readily obtained by reduction and brosylation of the Diels-Alder product of cyclopenta-1,3-diene (cyclohexa-1,3-diene) and ethyl acrylate. Various reactions of (11), including conversion into the parent heterocycle, were described. The dilithio-salt (13), obtained from toluene-a-thiol and two... 

Reaction of free-base porphyrin compounds with iton(II) salts in an appropriate solvent results in loss of the two N—H protons and insertion of iron into the tetradentate porphyrin dianion ligand. Five-coordinate iton(III) porphyrin complexes (hemins), which usually have the anion of the iton(II) salt for the fifth or axial ligand, ate isolated if the reaction is carried out in the presence of air. Iron(II) porphyrin complexes (hemes) can be isolated if the reaction and workup is conducted under rigorously anaerobic conditions. Typically, however, iton(II) complexes are obtained from iton(III) porphyrin complexes by reduction with dithionite, thiolate, borohydtide, chromous ion, or other reducing agents. 

Thioetherification of PECH is feasibly performed in DA-solvents as already described in the patent (20J. For example, the highest substitution was obtained by the reaction of P(ECH-EO)(1 1 copolymer of epichloro-hydrin and ethylene oxide) and equimolar thiophenoxide in HMPA at 100°C for 10 h as DS 83% for sodium and 93% for potassium salts. The DS in our nucleophilic substitution was estimated by the elemental analysis as well as the titration of liberated chloride ion with mercuric nitrate (21). In the latter method, reacted medium was pretreated with hydrogen peroxide when the reductive nucleophiles which can react with mercuric ion were used. As described before for PVC, thiolation was also achieved conveniently with iso-thiuronium salt followed by alkaline hydrolysis without the direct use of ill-smelling thiolate. The thiolated PECH obtained are rubbery solids, soluble in toluene, methylene chloride, ethyl methyl ketone and DMF and insoluble in water, acetone, dioxane and methanol. 

The formation of complexes of l,2,3,4-thiatriazole-5-thiol has been well described in CHEC-II(1996) 1,2,3,4-thiatriazole-5-thiol can form complexes with various metals such as palladium, nickel, platinum, cobalt, zinc, etc. <1996CHEC-II(4)691>. These complexes can be prepared either by cycloaddition reactions of carbon disulfide with metal complexes of azide anion (Equation 20) or directly from the sodium salt of l,2,3,4-thiatriazole-5-thiol with metal salts. For instance, the palladium-thiatriazole complex 179 can be obtained as shown in Equation (20) or it may be formed from palladium(ll) nitrate, triphenylphosphine, and sodium thiatriazolate-5-thiolate. It should be noted that complexes of azide ion react with carbon disulfide much faster than sodium azide itself. 

Like alkoxide ions, thiolate, dithiocarbamate and O-ethyl dithiocarbonate anions easily undergo nucleophilic addition at the 2-position of 1,3-dithiolylium salts (31) in boiling ethanol or acetonitrile with formation of derivatives (47) (80AHC(27)151). 

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