Absorption Spectrum of the Aggregated Radical Anion of Sulfur Dioxide Produced by γ-Irradiation

Ito, Osamu; Kuwashima, Shigeru

doi:10.1246/bcsj.49.327

Cited by 5 publications

(4 citation statements)

References 11 publications

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“…It has been proposed that the thermal decomposition of episulfones with extrusion of SO 2 does not occur through homolysis of the S−C bond but through expansion of the three-membered ring to a less strained four-membered ring sultine followed by further expansion to a five-membered 1,3,2-dioxathiolane ring. The loss of SO 2 from this last species becomes preferred over the sultine because the loss can be concerted and stereospecific. − However, the reaction pathways after thermal or photochemical activation are not necessarily the same, since the excited-state from which the reaction starts after light absortion may have geometric, energetic, and thermodynamic properties that are very different from those of its corresponding ground state. Thus, the proposal in Scheme is the one that fulfills better the experimental observations.…”

Section: Resultsmentioning

confidence: 99%

“…The loss of SO 2 from this last species becomes preferred over the sultine because the loss can be concerted and stereospecific. [42][43][44][45][46] However, the reaction pathways after thermal or photochemical activation are not necessarily the same, since the excited-state from which the reaction starts after light absortion may have geometric, energetic, and thermodynamic properties that are very different from those of its corresponding ground state. Thus, the proposal in Scheme 7 is the one that fulfills better the experimental observations.…”

Section: Resultsmentioning

confidence: 99%

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Reactivity of the Thermally Stable Intermediates of the Reduction of SO₂ on Carbons and Mechanisms of Insertion of Organic Moieties in the Carbon Matrix

et al. 2007

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The reduction of SO 2 on carbons proceeds through reactive intermediates bound to the carbon matrix, which were postulated to be 1,2-oxathiene 2-oxide (or sultine), and 1,3,2-dioxathiolane that decomposes to produce an episulfide and CO 2 . The reactivity of these intermediates was studied in this work through several reactions, using XPS and NMR spectra to postulate their mechanisms. When modified activated carbon obtained after reaction with SO 2 at 630 °C was heated at 900 °C, it was observed that the changes of the XPS spectrum resulted from the forward reaction of decomposition of the oxidized intermediate with S-transfer to produce the episulfide and CO 2 and the reverse reaction with expulsion of SO 2 . Strong bases hydrolyzed the dioxathiolane intermediate and the episulfide. The thiolysis, aminolysis, and reaction of alkyl halides with modified activated carbon occurred with the insertion of the organic moiety in the carbon matrix. Laser photolysis at 266 nm in t-butanol showed insertion of t-butoxide on the matrix. Consistent mechanisms for these reactions were postulated. These results provide additional evidence on the mechanism of reduction of SO 2 on carbons and the chemical nature of the intermediates, offering a new method to modify the physical and chemical properties of a carbon matrix by functionalization with an organic moiety.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Reactivity of the Thermally Stable Intermediates of the Reduction of SO₂ on Carbons and Mechanisms of Insertion of Organic Moieties in the Carbon Matrix

et al. 2007

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“…It has been proposed that the thermal decomposition of episulfones with extrusion of SO 2 does not occur through homolysis of the S–C bond, but through expansion of the three‐membered ring to a less strained four‐membered ring sultine followed by further expansion to a five‐membered 1,3,2‐dioxathiolane ring. The loss of SO 2 from this last species becomes preferred over the sultine because the loss can be concerted and stereospecific . However, the reaction pathways after thermal or photochemical activation are not necessarily the same, because the excited state from which the reaction starts after light absorption may have geometric, energetic, and thermodynamic properties that are very different from those of its corresponding ground state.…”

Section: Mechanismmentioning

confidence: 99%

Kinetics and mechanisms in flow systems: reduction of SO₂ on carbons

Humeres

Moreira

2012

J of Physical Organic Chem

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Surface‐science studies of some reactions have allowed postulating the mechanisms using a variety of techniques. The surface chemistry of Group IV elements has been particularly studied recently because Si, Ge, and C are semiconductors, and the surface organic chemistry to functionalize these elements has seen immense progress in recent years. In this review article we describe the methodology used to study the mechanism of a solid–gas reaction, the reduction of SO2 on carbons, and the necessary conditions that allowed the measurement of the solid conversion and product distribution when the kinetics was chemically controlled and the reaction had reached the steady state. The reaction was first‐order with respect to SO2 and with respect to carbon and the stoichiometry was determined from the product distribution. The reaction proceeds through two thermally stable reaction intermediates bound to the surface, a six‐membered ring 1,3,2‐dioxathiolane and a five‐membered ring 1,2‐oxathietene 2‐oxide or γ‐sultine, both species being in equilibrium. The reaction was shown to be reversible. The primary product is an episulfide that, after a series of consecutive reactions of atomic sulfur, is able to free sulfur. The reactivity of the intermediates and the episulfide was studied for several reactions and consistent mechanisms were postulated from the X‐ray photoelectron spectroscopy and solid state nuclear magnetic resonance spectra. Aminolysis and the reaction with alkyl halides resulted on the insertion of the alkyl moiety in the episulfide primary product, while the thiolysis and photolytic alcoholysis resulted in the insertion of the alkyl moiety in the oxidized intermediates. Copyright © 2012 John Wiley & Sons, Ltd.

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“…The absorbance of them was decreased significantly by the addition of radical anion quencher CCl4. These absorption maxima are similar to the radical anion of sulfonyl groups which is produced by gammairradiation in 2-methyltetrahydrofuran at 77 K [9][10][11]. The formation of the radical anion is due to the electron affinity of the sulfonyl group in the polymer main chain.…”

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confidence: 60%

Photo-degradation and electron beam-induced degradation of poly(pentamethyldisilylstyrene sulfone)s.

Watanabe

Sakakibara

Ito

et al. 1991

J. Photopol. Sci. Technol.

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Positive tone polysulfone resists have been studied extensively because they have weak C-S bond in the main chain upon UV light exposure. However, poly(olefin sulfone)s do not have UV absorption longer than 200 nm. The sensitivity of polysulfones as deep-UV resists can be endowed by incorporation of pendant aromatic ring into their structure. Organometallic polymers, primarily silicon-containing polymers are significantly interested in bilayer lithography because of the high oxygen plasma etch resistance. Poly(pentamethyldisilylstyrene sulfone)s have two functional groups, phenyl group and disilyl group in the polymer side chain. Phenyl group in the side chain increases the absorption in UV region and the high content of silicon atom enhances the oxygen plasma resistance. The incorporation of pentamethyldisilyl group also enhances the solubility of the polysulfone. Alternating poly(styrene sulfone) is insoluble in usual solvents whereas alternating poly(pentamethyldisilystyrene sulfone) is highly soluble to usual organic solvents. These features of poly(pentamethyldisilylstyrene sulfone)s are to be expected for a high performance photo-resist. Polysulfones are also applicable as positive tone electron beam resist owing to the high sensitivity of the C-S bond upon electron beam. O'Donnell et al. [ l ] and Bowden et al. [2] have investigated the radiation-induced degradation of poly(olefin sulfone)s extensively.Although there are many papers reporting the resist characterization, few papers discuss the mechanism of the degradation on the basis of the direct observation of transient intermediates.One of the reasons is the complication of the degradation in solid state because the rapid reaction among the unstable intermediates easily occurs in the dense system and the proceeding complicated reactions prevent the observation of transient intermediates produced in the first stage of the degradation. The degradation in solution is somewhat different from that in solid state, however, it simplifies the reaction and affords useful information about the assignment of transient intermediates. In this paper we

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Absorption Spectrum of the Aggregated Radical Anion of Sulfur Dioxide Produced by γ-Irradiation

Cited by 5 publications

References 11 publications

Reactivity of the Thermally Stable Intermediates of the Reduction of SO₂ on Carbons and Mechanisms of Insertion of Organic Moieties in the Carbon Matrix

Reactivity of the Thermally Stable Intermediates of the Reduction of SO₂ on Carbons and Mechanisms of Insertion of Organic Moieties in the Carbon Matrix

Kinetics and mechanisms in flow systems: reduction of SO₂ on carbons

Photo-degradation and electron beam-induced degradation of poly(pentamethyldisilylstyrene sulfone)s.

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Absorption Spectrum of the Aggregated Radical Anion of Sulfur Dioxide Produced by γ-Irradiation

Cited by 5 publications

References 11 publications

Reactivity of the Thermally Stable Intermediates of the Reduction of SO2 on Carbons and Mechanisms of Insertion of Organic Moieties in the Carbon Matrix

Reactivity of the Thermally Stable Intermediates of the Reduction of SO2 on Carbons and Mechanisms of Insertion of Organic Moieties in the Carbon Matrix

Kinetics and mechanisms in flow systems: reduction of SO2 on carbons

Photo-degradation and electron beam-induced degradation of poly(pentamethyldisilylstyrene sulfone)s.

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Reactivity of the Thermally Stable Intermediates of the Reduction of SO₂ on Carbons and Mechanisms of Insertion of Organic Moieties in the Carbon Matrix

Reactivity of the Thermally Stable Intermediates of the Reduction of SO₂ on Carbons and Mechanisms of Insertion of Organic Moieties in the Carbon Matrix

Kinetics and mechanisms in flow systems: reduction of SO₂ on carbons