Thiophenol-sulfur reaction

Data assembled by Parker (201 demonstrate these effects for bimolecular reactions involving sulfur nucleophiles and haloaliphatic substrates. As an illustration for the case of Reactions 4, the S 2 displacement of iodide from CH3I by SCN at 25°C is accelerated relative to its rate in water tty 0.2 log units in methanol, by 1.1 log units in 10% aqueous dimethyl sulfoxide (v/v), and tty approximately 2.4 log units in dimethyl formamide (DMF). Furthermore, the rates of bimolecular elimination and substitution of cyclohexyl bromide in the presence of thiophenolate at 25°C both increase by 2.7 log units when the solvent is changed from ethanol to dimethylfonnamide (20). 

In early work on organosulfur compounds, Duess (I) and Hil-ditch (2) reported the preparation of various aromatic disulfides by condensation reactions of thiophenol on treatment with aluminum chloride and sulfuric acid, respectively. Macallum (3) was the first to report the preparation of a phenylene sulfide polymer. His procedure involved the reaction of sulfur, sodium carbonate, and dichlorobenzene in a sealed vessel. Polymers made by this scheme generally have more than one sulfur atom between benzene rings, as indicated by the structure —( C6H4S )w-. 

Figure 3, Effect of radical inhibitors on second order rate behavior of thiophenol/sulfur reaction (J30 Cj...

Figure 5. Effect of substituents on thiophenol/sulfur reaction—Hammett...

Figure 6. NMR spectra for thiophenol/sulfur reaction with increasing (1-4) reaction time. Region A—SH signal decreases with time. Region B—polysulfanes appear and subsequently decrease. Region C— crease in signal and increase in product (CgHg)gSj. ...

Figure 8, Relationship between induction period for thiophenol/sulfur reaction and concentration variation of intermediates...

Figure 8 compares the accumulation and disappearance of the intermediate products with the induction period observed in the second order kinetic analysis of the thiophenol-sulfur reaction. Inspection of Figure 8 shows that the HSa-H and ArS rH species reach their maximum concentration at a point near the termination of the induction period. 

However, disappointingly poor selectivities were observed with sulfur nucleophiles. The high reactivity of the sulfur nucleophiles resulted in rapid nucleophilic displacement reactions relative to the epimerisation process and this may explain the lack of selectivity (Scheme 1.12). Moreover, the results of DKR reactions using sulfur nucleophiles are in agreement with the observed dichotomy methyl thioglycollate and benzyl mercaptan behaved similarly to amines, whereas thiophenol (which should be in the form of the thiophenolate anion under the reaction conditions used) showed the same preferential reactivity as the metallated nucleophiles. 

Make acid yields coumaUc acid when treated with fuming sulfuric acid (19). Similar treatment of malic acid in the presence of phenol and substituted phenols is a facile method of synthesi2ing coumarins that are substituted in the aromatic nucleus (20,21) (see Coumarin). Similar reactions take place with thiophenol and substituted thiophenols, yielding, among other compounds, a red dye (22) (see Dyes and dye intermediates). Oxidation of an aqueous solution of malic acid with hydrogen peroxide (qv) cataly2ed by ferrous ions yields oxalacetic acid (23). If this oxidation is performed in the presence of chromium, ferric, or titanium ions, or mixtures of these, the product is tartaric acid (24). Chlorals react with malic acid in the presence of sulfuric acid or other acidic catalysts to produce 4-ketodioxolones (25,26). 

The earliest reported reference describing the synthesis of phenylene sulfide stmctures is that of Friedel and Crafts in 1888 (6). The electrophilic reactions studied were based on reactions of benzene and various sulfur sources. These electrophilic substitution reactions were characterized by low yields (50—80%) of rather poorly characterized products by the standards of 1990s. Products contained many by-products, such as thianthrene. Results of self-condensation of thiophenol, catalyzed by aluminum chloride and sulfuric acid (7), were analogous to those of Friedel and Crafts. 

The action of sulfur nucleophiles like sodium bisulfite and thiophenols causes even pteridines that are unreactive towards water or alcohols to undergo covalent addition reactions. Thus, pteridin-7-one smoothly adds the named S-nucleophiles in a 1 1 ratio to C-6 (65JCS6930). Similarly, pteridin-4-one (73) yields adducts (74) in a 2 1 ratio at C-6 and C-7 exclusively (equation 14), as do 4-aminopteridine and lumazine with sodium bisulfite. Xanthopterin forms a 7,8-adduct and 7,8-dihydropterin can easily be converted to sodium 5,6,7,8-tetrahydropterin-6-sulfonate (66JCS(C)285), which leads to pterin-6-sulfonic acid on oxidation (59HCA1854). 

These reactions are convenient methods for putting sulfur-containing groups onto an aromatic ring. With Ar S", diazosulfides Ar—N=N—S—Ar are intermediates, which can in some cases be isolated. Thiophenols can be made as shown above, but more often the diazonium ion is treated with EtO—CSS" or S2", which give the expected products, and these are easily convertible to thiophenols. Aryl triflates have been converted to the aryl thiol using NaST(P5) and a palladium catalyst, followed by treatment with tetrabutylammonium fluoride. See also 14-27. 

Part C of the present procedure illustrates a mild method for effecting the elimination of thiophenol from thioacetals and thioketals under essentially neutral conditions. The reaction of simple thioacetals and thioketals with bis[copper(I) trifluoro-methanesulfonate] benzene complex in benzene-tetrahydrofuran at room temperature affords vinyl sulfides in high yield (Table I). The reaction presumably occurs by coordination of the thiophilic copper(I) reagent with sulfur, heterolysis to a phenylthio-stabilized... 

The reaction of crotonaldehyde and methyl vinyl ketone with thiophenol in the presence of anhydrous hydrogen chloride effects conjugate addition of thiophenol as well as acetal formation. The resulting j3-phenylthio thioacetals are converted to 1-phenylthio-and 2-phenylthio-1,3-butadiene, respectively, upon reaction with 2 equivalents of copper(I) trifluoromethanesulfonate (Table I). The copper(I)-induced heterolysis of carbon-sulfur bonds has also been used to effect pinacol-type rearrangements of bis(phenyl-thio)methyl carbinols. Thus the addition of bis(phenyl-thio)methyllithium to ketones and aldehydes followed by copper(I)-induced rearrangement results in a one-carbon ring expansion or chain-insertion transformation which gives a-phenylthio ketones. Monothioketals of 1,4-diketones are cyclized to 2,5-disubstituted furans by the action of copper(I) trifluoromethanesulfonate. ... 

The temperature at which elimination of thiophenol occurs depends on the substituents on the sulfur-bearing carbon. Thioke-tals react rapidly at 25°. In some cases the elimination of thiophenol from the less reactive thioacetals may also be performed at 25°. However, in the present case the combined inductive effects of the vinyl and methoxy groups evidently destabilize the incipient car-bonium ion and necessitate a higher temperature for the reaction. 

CENTRAL RING CONTAINING ONE HETEROATOM Reaction of 2-bromobenzoic acid (1) with chloroSulfonic acid proceeds to afford the sulfonyl chloride 2 treatment with dimethylamine leads to the corresponding sulfonamide (3). Condensation of bromoacid 3 with the anion from thiophenol in the presence of copper powder results in displacement of halogen by sulfur... 

Thiophenolate complexes have been discussed, however, a considerable amount of alkylthiolate zinc chemistry is also known. The zinc alkylthiolate complexes with methanethiolate, ethanethiolate, and /. so-propylthiolate have been synthesized and characterized as precursors for ZnS formation. Thermolysis studies demonstrated the formation of ZnS and release of dimethylsulfide. Reactivity was similar with only the rm-propyl derivative showing much slower reaction.523 The polyzincate Zni0S4(SEt)i2L4 is a well-characterized neutral zinc sulfur compound.524... 

This is a general reaction. It can be used for preparing other selenophenols whenever the desired Grignard reagent can be obtained. The submitter has made the three selenocresols, p-hromophen y 1 scl enophenol, and m-butylselenol by this procedure. He has also obtained thiophenols by the substitution of sulfur for selenium. 

Addition of alcohol occurs on P=N bond of 11,2,3]diazaphospholo[ 1,5-a pyridine (2) and P=C bond of 11,4,2 diazaphospholo[4,5-a Ipyridinc (76) in the presence of sulfur or selenium. In the case of 2, addition is followed by 1,3-H shift and a catalytic amount of the respective alkoxide is required for completion of reaction at room temperature. The reaction of 2 with thiophenol is completed at reflux temperature in the presence of sulfur (Scheme 24) [88],... 

Thiophenyl acetates (366 R = Me) and propionates (366 R = Et) react with electrogenerated polysulflde ions S3 in DMF to yield thiocarboxylate ions, thiolate ions, and phenyl tetrasulfanide (367), the last deriving from the reaction of thiolate ions with sulfur (Scheme 48). Smdies of the aminolysis by a set of substimted anilines of Y-aryl dithio-2-thiophenates (368 X = S) and dithio-2-furoates (368 X = O) in acetonitrile have shown that the rate-determining step in these reactions is the departure of the thiophenolate ion from the zwitterionic tetrahedral intermediate T= = (Scheme 49). Experiments with deuteriated anilines yielded k i/IcQ values of 1.7-1.9,... 

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