ORGANIC AND BIOLOGICAL SPECTROCHEMICAL STUDIES: XXIII. CONFORMATION OF THE <i>p</i>-DIMETHOXYBENZENE CATION RADICAL IN CONCENTRATED SULFURIC ACID

Forbes, W. F.; Sullivan, Paul D.

doi:10.1139/v66-225

Cited by 32 publications

(7 citation statements)

References 8 publications

(5 reference statements)

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“…The extinction coefficients were calculated by as- °The error in the k values is ±10%. 6 k values are equal to Kb&c from eq 6.c An additional absorption maximum at 420 nm was observed and, as yet, is unassigned.…”

Section: Resultsmentioning

confidence: 97%

“…In agreement with these kinetic results, the stationary concentration of the radical cations of anisóle and 1, °Indexes refer to ring positions. 6 The assignment of the coupling constants to individual ortho and meta protons, respectively, is as yet arbitrary. found by ESR to be considerably lower than that of 1,2and 1,4-DMB and 1,2,3-and 1,2,4-DMB, respectively.…”

Section: Resultsmentioning

confidence: 99%

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Formation of radical cations of methoxylated benzenes by reaction with hydroxyl radicals, thallium(2+), silver(2+), and peroxysulfate (SO4.-) in aqueous solution. Optical and conductometric pulse radiolysis and in situ radiolysis electron spin resonance study

O’Neill¹,

Steenken²,

1975

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zene with Tl2+, Ag2+, SO4•-, and OH, respectively, were investigated in aqueous solution using optical and conductometric pulse radiolysis and in situ radiolysis ESR for detection. Tl2+ and Ag2+ were produced by reaction of OH with Tl+ and Ag+, respectively. SO4•was generated by reaction of eaq" with persulfate. Tl2+, Ag2+, and SO4•-react with the methoxylated benzenes by electron transfer to yield radical cations and Tl+, Ag+, and SO42-, respectively. In the absence of cyclohexadienyl radicals the radical cations decay by second-order kinetics with rate constants ranging from <4 X 103 to 1 X 109 M-1 sec-1 depending on the positions of the methoxy groups relative to each other. OH radicals react with the methoxylated benzenes by addition to the aromatic ring with diffusion-controlled rates. Depending on conditions, the hydroxycyclohexadienyl radicals thus formed subsequently undergo three different types of reaction: (a) bimolecular decay (k values ranging from 8 X 108 to 2 X 109 M-1 sec-1); (b) reaction with protons to yield radical cations (k values from 2 X 108 to 1.4 X 109 M-1 sec-1); and (c) reaction with radical cations (k values from 8.6 X 108 to 3.5 X 109 M-1 sec-1). The assignment of the optical absorption spectra of the radical cations and the determination of the respective extinction coefficients is based on a combination of optical and conductivity data. The radical cation yield obtained at pH 1 by reaction of protons with the OH adducts of the substrates amounts to >90% in the case of anisóle, 1,3-dimethoxybenzene, and 1,3,5-trimethoxybenzene.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Formation of radical cations of methoxylated benzenes by reaction with hydroxyl radicals, thallium(2+), silver(2+), and peroxysulfate (SO4.-) in aqueous solution. Optical and conductometric pulse radiolysis and in situ radiolysis electron spin resonance study

O’Neill¹,

Steenken²,

1975

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“…Otherwise, the room-temperature EPR characterization of [3] þ , as obtained by dissolution of 1,4-dimethoxybenzene in acidic media (i.e. concentrated H 2 SO 4 [15], CH 3 NO 2 /AlCl 3 [5e, 5g] or BF 3 [5g]), dates back to 40 years ago [16].…”

Section: Resultsmentioning

confidence: 99%

Room-temperature long-lived [Nb2F11]− salts of radical cations of simple arenes: EPR, UV–Vis and DFT results

Marchetti¹,

Pampaloni²,

Pinzino³

2011

Journal of Organometallic Chemistry

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“…The synthesis and characterization of fairly stable radical cations by one‐electron oxidation of simple aromatic molecules has been widely investigated. The most stable derivatives have been obtained from 1,4‐diaminobenzenes (Wurster’s salts),1 monoamino benzenes2 and mono‐ and dialkoxy benzenes,3 by both chemical and electrochemical3b,d,e,g,n methods. Examples of suitable chemical oxidants are Br 2 ,1b Ag + ,2 BF 3 or AlCl 3 ,3i,l H 2 SO 4 3j,k and perfluorobis[1‐(2‐fluorosulfonyl)ethoxy]propionyl peroxide 3a…”

Section: Introductionmentioning

confidence: 99%

Long‐Lived Radical Cation Salts Obtained by Interaction of Monocyclic Arenes with Niobium and Tantalum Pentahalides at Room Temperature: EPR and DFT Studies

Marchetti¹,

Pampaloni²,

Pinzino³

2013

Chemistry A European J

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The 1:3 reactions of the alkoxy arenes 1,4-(MeO)2 C6 H4 and 1,4-F2 -2,5-(MeO)2 C6 H2 with TaF5 in chloroform at 40-50 °C resulted in formation in about 35 % yield of the long-lived radical cation salts [1,4-(MeO)2 C6 H4 ][Ta2 F11 ] (2 a) and [1,4-F2 -2,5-(MeO)2 C6 H2 ][Ta2 F11 ] (2 b), respectively. The non-alkoxy-substituted [arene][M2 X11 ] [M=Ta, X=F: arene=C6 H5 Me (2 c), 1,4-C6 H4 Me2 (2 d), C6 H5 F (2 e), C6 H5 NO2 (2 f); M=Nb, X=F: arene=C6 H5 Me (4 a), 1,4-C6 H4 Me2 (4 b), C6 H5 F (4 c), C6 H5 NO2 (4 d); M=Ta, X=Cl: arene=1,4-C6 H4 Me2 (5)] were obtained from the 3:1 reactions of MX5 with the appropriate arene in chloroform at temperatures in the range 40-90 °C. Compounds 2-5 were detected by EPR spectroscopy (in CHCl3 ) at room temperature, and their gas-phase structures were optimized by DFT calculations. Formation of the M(IV) species [MX4 (NCMe)2 ] [M=Ta, X=F (3 a); M=Nb, X=F (3 b); M=Ta, X=Cl (3 c)] was ascertained by EPR spectroscopy on solutions obtained by treatment of the reaction mixtures with acetonitrile. Non-selective reactions occurred upon combination of 1,4-F2 -2,5-(MeO)2 C6 H2 with AgNbF6 (in CH2 Cl2 ) and 1,4-(MeO)2 C6 H4 with SbF5 .

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ORGANIC AND BIOLOGICAL SPECTROCHEMICAL STUDIES: XXIII. CONFORMATION OF THE p-DIMETHOXYBENZENE CATION RADICAL IN CONCENTRATED SULFURIC ACID

Cited by 32 publications

References 8 publications

Formation of radical cations of methoxylated benzenes by reaction with hydroxyl radicals, thallium(2+), silver(2+), and peroxysulfate (SO4.-) in aqueous solution. Optical and conductometric pulse radiolysis and in situ radiolysis electron spin resonance study

Formation of radical cations of methoxylated benzenes by reaction with hydroxyl radicals, thallium(2+), silver(2+), and peroxysulfate (SO4.-) in aqueous solution. Optical and conductometric pulse radiolysis and in situ radiolysis electron spin resonance study

Room-temperature long-lived [Nb2F11]− salts of radical cations of simple arenes: EPR, UV–Vis and DFT results

Long‐Lived Radical Cation Salts Obtained by Interaction of Monocyclic Arenes with Niobium and Tantalum Pentahalides at Room Temperature: EPR and DFT Studies

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