Benzenethiyl Radicals Research Articles

ChemInform Abstract: Reductive Addition of the Benzenethiyl Radical to Alkynes by Amine‐Mediated Single Electron Transfer Reaction to Diphenyl Disulfide.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Reductive Addition of the Benzenethiyl Radical to Alkynes by Amine-Mediated Single Electron Transfer Reaction to Diphenyl Disulfide

Hydrothiolation of alkynes proceeds with diphenyl disulfide and tripropylamine. Amine-mediated single electron transfer to diphenyl disulfide can be proposed for the reaction mechanism. Applications of the method to radical cyclizations of eneyne compounds are also presented.

Photochemical reactions of thiols with organic nitrates — Oxygen atom transfer via a thionitrate

Nitroglycerin is an organic nitrate that has been used in the clinical treatment of angina for 130 years, yet important details of its mechanism of action remain unanswered. The biological activity of nitrates suggests that they are bioactivated to NO via a three-electron reduction. The involvement of free or bound protein thiols in this reduction has often been proposed. To examine the involvement of thiyl radicals in such a process, the photochemical generation of benzenethiyl radical from thiol and disulfide precursors was studied in the presence of isopropyl nitrate. Analysis of reaction products and kinetics led to the conclusion that photolysis of the nitrate to NO2dominated the observed photochemistry. Formation of sulfonothioate and NO as products, and trapping of NO2by 4-chlorophenol, indicated a mechanism involving oxygen atom transfer from N to S via a thionitrate intermediate. The results of the study did not indicate a rapid reaction between thiyl radical and organic nitrate. Despite weak nitrate absorption of light >300 nm and a relatively high BDE for homolysis to give NO2, the photochemistry under thiyl-generating conditions was driven by nitrate photolysis to NO2. A novel nitrate, containing a phenyl disulfanyl group linked to nitrate groups, did not undergo photolysis to NO2or generate sulfonothioate, but did yield NO. These observations suggest that reaction between thiyl radicals and nitrates leading to NO release is a viable pathway, but it is subservient to other competing reactions, such as photolysis, in the case of IPN, and reaction with thiolate, in the case of the novel nitrate.Key words: nitrate, photolysis, thiyl radical, nitrogen dioxide, nitric oxide.

Catalytic Reduction of Diphenyl Disulfide by Cobalt(I) Salen Electrogenerated at a Carbon Cathode in Acetonitrile

We have employed cyclic voltammetry and controlled‐potential electrolysis to explore the catalytic reduction of diphenyl disulfide by electrogenerated cobalt(I) salen in acetonitrile containing various tetraalkylammonium salts as well as tetraphenylphosphonium bromide. Cobalt(I) salen reacts with diphenyl disulfide in an outer‐sphere electron‐transfer reaction to produce the radical‐anion of diphenyl disulfide, which breaks apart to form benzenethiolate and a benzenethiyl radical. This latter radical is much easier to reduce than diphenyl disulfide and can accept another electron homogeneously from either the radical‐anion or electrogenerated cobalt(I) salen to give benzenethiolate. Such a mechanistic picture is unlike that found earlier for the catalytic reduction of halogenated organic compounds by electrogenerated cobalt(I) salen. In the course of this investigation, we have discovered that, when electrolyzed solutions containing benzenethiolate are removed from the electrolysis cell and injected directly into a gas chromatograph for analysis, a reaction occurs in the injector port between benzenethiolate and the tetraalkylammonium (or tetraphenylphosphonium) moiety of the supporting electrolyte to give an alkyl phenyl sulfide and a trialkylamine (or diphenyl sulfide and triphenylphosphine). As part of this research, we have examined the direct reduction of diphenyl disulfide at glassy carbon cathodes, and we have determined the lifetime of the radical‐anion of diphenyl disulfide.

Substituent Effects on the Addition Reaction Rate of Thiophenols to Ethynylbenzenes as a Model of Polyaddition. Study on the Relative Reactivity and Reaction Mechanism on the Basis of Hammett Correlation

The addition reactions of thiophenols to ethynylbenzenes having p-methoxy, p-methyl, and p-chloro substituent groups occurred readily without appreciable side reactions. Adducts of the anti-Markownikoff’s structure were obtained in 95–99% yields. The relative reactivities of the addition reactions of benzenethiyl radical to substituted ethynylbenzenes, the rate-determining step, were found to be quite opposite to those of substituted benzenethiyl radicals to ethynylbenzene. For example, p-methoxyethynylbenzene has the highest reactivity in the ethynylbenzenes. The p-methoxybenzenethiyl radical exhibits the lowest reactivity. The relative rates of the chain transfer reaction among β-phenylthiostyrylene radical (φĊ=CHSφ) and thiophenols were also determined. That is, the electron-donating p-substituent group on the thiophenols increased the chain transfer reaction rate. These relative reactivities were correlated by three Hammett’s equations. Better correlation was found with the Brown-Okamoto’s equation and Yamamoto’s equation considering a resonance effect. The results are discussed in relation to the transition state of the addition reaction of thiophenols to ethynylbenzenes. The substituent effects on the addition reactions between thiophenols and styrenes or thiophenols and ethynylbenzenes are comparatively discussed based on the energy levels of HOMO, SOMO, and LUMO calculated by MINDO/3. Polyaddition reactivity of 1,4-benzenedithiol to 1,4-diethynylbenzene was also estimated to be four times higher than the addition of thiophenol to ethynylbenzene.

ChemInform Abstract: Synthesis of Vinylcyclopentanes (III) from Vinylcyclopropanes (I) and Alkenes (II) Promoted by Benzenethiyl Radical.

ChemInform Abstract: Synthesis of Vinylcyclopentanes (III) from Vinylcyclopropanes (I) and Alkenes (II) Promoted by Benzenethiyl Radical.

新規ラジカル発生法とその有機合成への応用 Ｒ３ＳｎＨ‐Ｅｔ３Ｂ系によるラジカル反応

Synthetically useful radical reactions mediated by Et3B are described. An addition of catalytic amount of Et3B to a solution of triphenylstannane, triphenylgermane, or benzenethiol in toluene promotes the effective formation of the corresponding triphenylstannyl, triphenylgermyl, or benzenethiyl radical, respectively. Topics are (1) Et3B induced radical addition of R3SnH to acetylenes and its application to cyclization reaction, (2) Et3B induced stereoselective radical addition of Ph3GeH to acetylenes and its application to isomerization of olefins, (3) Et3B induced radical addition of thiols to acetylenes, (4) A facile reduction of dithiocarbonates with n-Bu3SnH-Et3B, (5) Et3B induced hydrodehalogenation of organic halides by tin hydrides, and (6) Et3B-mediated Reformatsky type reaction and three component coupling reaction of alkyl iodides, methyl vinyl ketone, and carbonyl compounds.

Synthesis of vinylcyclopentanes from vinylcyclopropanes and alkenes promoted by benzenethiyl radical

The reaction of dimethyl 2-vinylcyclopropane-1,1-dicarboxylate with butyl vinyl ether in the presence of a catalytic amount of PhSH provides dimethyl 3-butoxy-4-vinylcyclopentane-1,1-dicarboxylate in 82% yield.

Solvent effect on rates of free-radical reactions. 2. Addition of the p-(dimethylamino)benzenethiyl radical to .alpha.-methylstyrene

Solvent effect on rates of free-radical reactions. 2. Addition of the p-(dimethylamino)benzenethiyl radical to .alpha.-methylstyrene

Determination of addition rates of benzenethiyl radicals to alkynes by flash photolysis. Structures of produced vinyl-type radicals

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDetermination of addition rates of benzenethiyl radicals to alkynes by flash photolysis. Structures of produced vinyl-type radicalsOsamu Ito, Ryoichi Omori, and Minoru MatsudaCite this: J. Am. Chem. Soc. 1982, 104, 14, 3934–3937Publication Date (Print):July 1, 1982Publication History Published online1 May 2002Published inissue 1 July 1982https://doi.org/10.1021/ja00378a025RIGHTS & PERMISSIONSArticle Views243Altmetric-Citations42LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (487 KB) Get e-Alerts Get e-Alerts

Determination of addition rates of thiyl radicals to vinyl monomers by means of flash photolysis. 8. Polar effect in addition rates of substituted benzenethiyl radicals to .alpha.-methylstyrene determined by flash photolysis

Determination of addition rates of thiyl radicals to vinyl monomers by means of flash photolysis. 8. Polar effect in addition rates of substituted benzenethiyl radicals to .alpha.-methylstyrene determined by flash photolysis

Evaluation of addition rates of thiyl radicals to vinyl monomers by flash photolysis. 5. Polar effects in addition reactions of benzenethiyl radicals to substituted styrenes and .alpha.-methylstyrenes determined by flash photolysis

Evaluation of addition rates of thiyl radicals to vinyl monomers by flash photolysis. 5. Polar effects in addition reactions of benzenethiyl radicals to substituted styrenes and .alpha.-methylstyrenes determined by flash photolysis

Free radical substitution reaction on zirconium and hafnium organometallics

Di-t-butyl nitroxide readily substitutes alkyl zirconocenes and hafnocenes, Cp 2MR 2, by a rate-determining displacement of alkyl radicals to give high yields of O-alkyl- N, N-di-t-butylhydroxylamine and Cp 2M(R)ONBu t 2. A free radical substitution of di-benzylzirconocene by benzenethiyl radicals yields Cp 2Zr(SPh) 2.

Evaluation of addition rates of thiyl radicals to vinyl monomers by flash photolysis. 3. Polar effect in addition reactions of substituted benzenethiyl radicals

Evaluation of addition rates of thiyl radicals to vinyl monomers by flash photolysis. 3. Polar effect in addition reactions of substituted benzenethiyl radicals

Substituent effect on the rate constants for the reactions between benzenethiyl radicals and stable free radicals estimated by flash photolysis

Substituent effect on the rate constants for the reactions between benzenethiyl radicals and stable free radicals estimated by flash photolysis

Evaluation of addition rates of the thiyl radicals to vinyl monomers by flash photolysis. 2. Substituent effect on addition of substituted benzenethiyl radicals to methyl methacrylate or styrene

Evaluation of addition rates of the thiyl radicals to vinyl monomers by flash photolysis. 2. Substituent effect on addition of substituted benzenethiyl radicals to methyl methacrylate or styrene

Relative rate constants for hydrogen atom abstraction by the cyclohexanethiyl and benzenethiyl radicals

Relative values of the rate constants k (eq 1) for hydrogen atom abstraction from a number of organic substrates by cyclohexanethiyl and benzenethiyl radicals at 80/sup 0/C are reported. Good correlations with both sigma and sigma/sup +/ constants were found for ring-substituted ethylbenzene and cumene derivatives, and some limited data for toluenes also are reported. Two new methods were developed to obtain these data; the key feature of both is that tritium-labeled thiol (RSH*) is used as a solvent. In this environment, reversal of the hydrogen abstraction reaction (eq 2) leads to labeling of the hydrogen donor (QH), and k is related to the radioactivity incorporated into the recovered QH*. Isotope effects are involved in the calculations, but they can be evaluated independently. Thiyl radicals are found to be extremely selective, more so than even bromine atoms or CCL/sub 3/. radicals. Surprisingly, both cyclohexanethiyl and benzenethiyl radicals, and also bromine atoms, show remarkably similar polar effects; this is not what would be expected on the basis of heats of reaction or electron affinities. It is suggested that this similarity might be attributable to the similar polarizabilities of bromine atoms and thiyl radicals. 6 tables, 3 figures.

Kinetics and Equilibrium Positions of cis-trans Isomerization of 1,2-Bis(phenylthio)ethylene and Its Exchange with Benzenethiyl Radicals

Abstract Kinetics of the cis-trans isomerization of 1,2-bis(phenylthio)ethylene induced by benzenethiyl radicals and the exchange of phenylthio group have been studied by using thiophenol-phenyl-14C Pseudo-first order rate constants for the isomerization and the exchange are 2.08±0.22×10−5 sec−1 and 2.03±0.26×10−5 sec−1 at 50°C, respectively. The cis/trans ratio of this olefin is 55–58/45–42 at the completion of the reaction, which differs from the value obtained from the reaction induced by iodine (48–49/51–52). The difference has been interpreted with the idea that the isomer composition in the cis-trans isomerization is determined by kinetic factors when the reaction is initiated by thiyl radicals.