Cationic Chain Reaction Research Articles

Synthesis of Methanesulfonic Acid Directly from Methane: The Cation Mechanism or the Radical Mechanism?

In 2019, Diaz-Urrutia and Ott developed a high-yield method for direct conversion of methane to methanesulfonic acid and proposed a cationic chain reaction mechanism. However, Roytman and Singleton questioned this mechanism, and they favored a free-radical mechanism. In the present paper, we studied both the cationic chain and radical mechanisms and found the radical mechanism is more favorable, since it has a much lower energy barrier. However, the radical mechanism has not considered the effect of ions for the reaction taking place in oleum. Thus, we studied a simple model of a protonated radical mechanism, which further lowers the energy barrier. Although the true mechanism for the CH4 + SO3 reaction could be more complicated in electrolyte solutions, this model should be helpful for the further study of the mechanism of this reaction.

Electro-Generated Acids Catalyzed Epoxyolefin Cyclizations via Cationic Chain Reactions

Electro-Generated Acids Catalyzed Epoxyolefin Cyclizations via Cationic Chain Reactions

Comment on "Activation of methane to CH3 +: A selective industrial route to methanesulfonic acid".

Díaz-Urrutia and Ott (Reports, 22 March 2019, p. 1326) report a selective conversion of methane to methanesulfonic acid that is proposed to occur by a cationic chain reaction in which CH3 + adds to sulfur trioxide (SO3) to form CH3-S(O)2O+ This mechanism is not plausible because of the solvent reactivity of CH3 +, the non-nucleophilicity of the sulfur atom of SO3, and the high energy of CH3-S(O)2O<sup/>.

ChemInform Abstract: Aromatic C—H Bond Functionalization Induced by Electrochemically in situ Generated Tris(p‐bromophenyl)aminium Radical Cation: Cationic Chain Reactions of Electron‐Rich Aromatics with Enamides.

An effective Friedel-Crafts alkylation reaction of electron-rich aromatics with N-vinylamides, induced by electrochemically in situ-generated TBPA radical cation, has been developed; the resulting adducts are produced in good to excellent yields. In the ex-cell type electrolysis, TBPA is transformed to its oxidized form in situ and subsequently employed as an electron transfer reagent to initiate a cationic chain reaction. An easily recoverable and reusable polymeric ionic liquid-carbon black (PIL-CB) composite was also utilized as a supporting electrolyte for the electrochemical generation of TBPA cation radical, without sacrificing efficiency or stability after four electrolyses. Cyclic voltammetry analysis and the results of control experiments demonstrate that the reaction of electron-rich aromatics and N-vinylamides occurs via a cationic chain reaction, which takes place though an oxidative activation of a C-H bond of electron-rich aromatics instead of oxidation of the N-vinylamide as previously assumed.

Aromatic C–H Bond Functionalization Induced by Electrochemically in Situ Generated Tris(p-bromophenyl)aminium Radical Cation: Cationic Chain Reactions of Electron-Rich Aromatics with Enamides

An effective Friedel-Crafts alkylation reaction of electron-rich aromatics with N-vinylamides, induced by electrochemically in situ-generated TBPA radical cation, has been developed; the resulting adducts are produced in good to excellent yields. In the "ex-cell" type electrolysis, TBPA is transformed to its oxidized form in situ and subsequently employed as an electron transfer reagent to initiate a cationic chain reaction. An easily recoverable and reusable polymeric ionic liquid-carbon black (PIL-CB) composite was also utilized as a supporting electrolyte for the electrochemical generation of TBPA cation radical, without sacrificing efficiency or stability after four electrolyses. Cyclic voltammetry analysis and the results of control experiments demonstrate that the reaction of electron-rich aromatics and N-vinylamides occurs via a cationic chain reaction, which takes place though an oxidative activation of a C-H bond of electron-rich aromatics instead of oxidation of the N-vinylamide as previously assumed.

ChemInform Abstract: Organic Reactions Mediated by Electrochemically Generated ArS+

AbstractReview: 147 refs.

Organic reactions mediated by electrochemically generated ArS+

Low-temperature electrochemical oxidation of ArSSAr was carried out to generate a pool of "ArS(+)". Spectroscopic studies ((1)H NMR and CSI-MS) of the resulting solution revealed the accumulation of ArS(ArSSAr)(+). The resulting "ArS(+)" pool reacted with alkenes and alkynes to give diarylthio-substituted products. The "ArS(+)" pool rapidly reacted with thioacetals to give the corresponding alkoxycarbenium ion pools, which reacted with various carbon nucleophiles (indirect cation pool method). The reaction of the alkoxycarbenium ion pools with stilbene derivatives in the presence of ArSSAr gave thiochroman derivatives. In addition to such stoichiometric reactions, a catalytic amount of "ArS(+)" serves as an initiator and a chain carrier of some cationic chain reactions involving intramolecular carbon-carbon bond formation. In situ generation of "ArS(+)" by electrochemical oxidation of ArSSAr with a catalytic amount of electricity in the presence of a substrate is also effective for such cationic chain reactions.

Addition of ArSSAr to dienes via intramolecular C–C bond formation initiated by a catalytic amount of ArS+

A catalytic amount of electrochemically generated "ArS+" ("ArS+" = ArS(ArSSAr)+) initiates a cation chain reaction of dienes that involves the addition of ArSSAr associated with stereoselective intramolecular carbon-carbon bond formation, and the direct (in-cell) electrolysis of a mixture of a diene and ArSSAr with a catalytic amount of electricity also effectively initiates the reaction.

Electron-Transfer-Catalyzed Dimerization oftrans-Anethole: Detection of the Distonic Tetramethylene Radical Cation Intermediate by Extractive Electrospray Ionization Mass Spectrometry

The desolvating droplets of EESI were used as microreactor for the mass spectrometric study of short-lived transients of reactions in condensed liquid phase in the millisecond time region. The electron-transfer-catalyzed dimerization of trans-anethole was investigated and the intermediates in the radical cation chain reaction were isolated and characterized by MS-MS. The distonic tetramethylene radical cation 3(o)(*+) was detected as intermediate, and its cyclization to give the cyclobutane radical cation 3(c)(*+) was observed giving strong evidence that the reaction takes place stepwise.

ChemInform Abstract: An Electroinitiated Cation Chain Reaction: Intramolecular Carbon—Carbon Bond Formation Between Thioacetal and Olefin Groups.

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.

Electro-Initiated Cationic Chain Reaction. Intramolecular C-C Bond Formation between Thioacetal and Olefin

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An Electroinitiated Cation Chain Reaction: Intramolecular Carbon–Carbon Bond Formation between Thioacetal and Olefin Groups

Olefinische Thioacetale reagieren in Gegenwart einer katalytischen Menge an ArS(ArSSAr)+ B(C6F5)4− – oder bei der Elektrolyse in Mischungen mit ArSSAr – effizient unter intramolekularer Kohlenstoff-Kohlenstoff-Kupplung (siehe Schema). Dieses Verfahren ist aussichtsreich für elektrochemisch ausgelöste Kationenkettenreaktionen in der organischen Synthese.

An Electroinitiated Cation Chain Reaction: Intramolecular Carbon–Carbon Bond Formation between Thioacetal and Olefin Groups

The treatment of an olefinic thioacetal with a catalytic amount of ArS(ArSSAr)+B(C6F5)4−, or the electrolysis of a mixture of an olefinic thioacetal and ArSSAr, gives rise to effective intramolecular carbon–carbon bond formation (see scheme). This transformation opens up great potential for electroinitiated cation chain reactions in organic synthesis.

Use of electrospray ionization mass spectrometry for the investigation of radical cation chain reactions in solution: detection of transient radical cations.

Electrospray ionization mass spectrometry (ESI-MS) coupled to a microreactor is an excellent tool for the investigation of reactions in solution. Here, we report the first results of our investigations into preparatively interesting electron-transfer-initiated chain reactions in solution which proceed via radical cations as reactive intermediates. The tris(p-bromophenyl)aminium hexachloroantimonate (1)-mediated [2+2] cycloaddition of trans-anethole (2) to give 1,2-bis(4-methoxyphenyl)-3,4-dimethylcyclobutane (3) was investigated. The reaction proceeds as a radical cation chain reaction via transient intermediates 2*+ and 3*+ that could be detected and characterized unambiguously directly in the reacting solution by ESI-MS/MS. The identity of the intermediates was confirmed by comparison with authentic MS/MS spectra of 2*+ and 3*+ obtained by atmospheric pressure chemical ionization mass spectrometry (APCI-MS). In addition, substrate and product can be monitored easily in the reacting solution by APCI-MS.

UV-Härtung von Beschichtungsstoffen basiert auf Vinylether

The photoinitiated polymerisation of different types of vinyl ether-based resins has been studied by real-time infrared spectroscopy. The cationic initiated chain reaction was shown to proceed extensively within seconds, on UV exposure of divinyl ether monomers in the presence of on arylsulfonium salt. Various factors affect the polymerisation kinetics, such as the type of photoinitiator, the light intensity and the viscosity of the mixture. Different kinds of tridimensional polymer networks have been produced by the UV-curing of hybrid systems made from a vinyl ether (VE) and a co-monomer. With triaaylate monomers associated with divinyl ethers, interpenetrating polymer networks or cross-linked copolymers with isolated VE units were generated, depending on the type of photoinitiator used. In the presence of electron acceptor monomers, such as maleates or maleimides, vinyl ether monomers undergo a ready copolymerisation on UV irradiation, by a radical-type mechanism, with the formation of an alternating copolymer.

Light‐induced cationic polymerization

AbstractMechanistic studies concerning the initiation of cationic chain reactions with the aid of diaryliodonium and triarylsulphonium salts are reviewed and recent results are presented. Laser flash photolysis in combination with pulse radiolysis experiments revealed evidence for a triplet path occurring parallel to the singlet deactivation route of electronically excited diphenyliodonium ions. The radical cations PhI+− and Ph2S+− were found to react selectively with nucleophiles, the former being more reactive than the latter. Moreover, various aspects of the photo‐initiated free radical‐promoted cationic polymerization of typical monomers such as tetrahydrofuran and butyl vinyl ether with the aid of acylphosphine oxides and other free radical initiators are discussed.

Radiation-Induced Pyrolysis of Poly(α-methylstyrene). Degradation by Cationic Chain Reactions

Radiation-Induced Pyrolysis of Poly(α-methylstyrene). Degradation by Cationic Chain Reactions

Disproportionation of trityl alkyl ethers. Synthesis of aldehydes and ketones in a cationic chain reaction involving hydride transfer

Disproportionation of trityl alkyl ethers. Synthesis of aldehydes and ketones in a cationic chain reaction involving hydride transfer

Cationic chain reaction in the radiolysis of ethanol vapor

Cationic chain reaction in the radiolysis of ethanol vapor

Radiation-induced dimerization of 1,3-cyclohexadiene. Solvent effects and the formation of the Diels-Alder dimers by a cationic chain mechanism

Abstract : The radiation-induced dimerization of 1,3-cyclohexadiene occurred by two simultaneous mechanisms: mechanism 1 produced mainly the endo and exo Diels-Alder products of 1,4,1',2' addition; mechanism 2 produced mainly the cis-anti-cis and cis-syn-cis isomeric products of 1,2,1',2' addition. Both mechanisms were sensitized by the aprotic solvents benzene, n-hexane, cyclohexane, and di-n-propyl ether, and were inhibited by the protic solvent ethanol. Mechanism 1 involved a cationic chain reaction in benzene, and probably also in the other aprotic solvents. In all the aprotic solvents the yield of the Diels-Alder products went through a maximum as the 1,3-cyclohexadiene (CHD) concentration was increased. There was no evidence of a chain in mechanism 2 and the yields of the corresponding dimers were relatively small. It appears that triplet-state CHD molecules were the immediate precursors of the dimers from mechanism 2, and that roughly half of the triplet CHD molecules resulted directly or indirectly from neutralization reactions. (Author)