The Behavior of Isobutane in Concentrated Sulfuric Acid<sup>1</sup>

Otvos, John W.; Stevenson, D. P.; Wagner, C. D.; Beeck, Otto

doi:10.1021/ja01156a075

Cited by 78 publications

(39 citation statements)

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“…Lewis-Säure-katalysierter H/D-Austausch unpolarer Arene. [24] In Über-einstimmung mit den Befunden von Otvos et al [25] Boix und Poliakoff berichteten von polymergebundenen Sulfonsäuren (Deloxan), die sie zur Deuterierung von aromatischen Verbindungen einsetzten. So wurden bei der Reaktion von Chinolin (17) oder Ethylbenzol (18) in überkriti-schem D 2 O bei 325 8C hervorragende Deuteriumübertra-gungen erzielt (Schema 9).…”

Section: Ph-wert-abhängiger H/d-austauschunclassified

Die Renaissance des H/D‐Austausches

et al. 2007

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Die steigende Nachfrage nach stabil isotopenmarkierten Verbindungen führt zu einem verstärkten Interesse an H/D‐Austauschreaktionen an Kohlenstoffatomen. Heutzutage werden Deuterium‐markierte Verbindungen als interne Standards in der Massenspektrometrie eingesetzt oder helfen dabei, mechanistische Theorien zu untermauern. Der Zugang zu diesen deuterierten Verbindungen erfolgt über einen Austausch von Wasserstoff gegen Deuterium im Zielmolekül deutlich effizienter und preiswerter als über die klassische Synthese. Schwerpunkt dieses Aufsatzes sind präparative Anwendungen der H/D‐Austauschreaktion zur Herstellung Deuterium‐markierter Substanzen. Die Fortschritte der letzten zehn Jahre werden zusammengefasst und kritisch bewertet.

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Section: Ph-wert-abhängiger H/d-austauschunclassified

Die Renaissance des H/D‐Austausches

et al. 2007

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“…[14,[16][17][18] In the case of isobutane, in contact with various solid acids at 150 8C, various authors proposed a mechanism based on carbenium ion intermediates, [19][20][21][22][23] similar to that occurring in concentrated sulfuric acid. [24,25] Recently, an alternative mechanism, for the same reaction but at room temperature, based on a carbonium ion type complex at the surface of the zeolite was published. [26] The authors explained the regioselectivity of the exchange as being due to steric hindrance and site accessibility in a confined environment and further supported their conclusion by a theoretical study.…”

Section: Introductionmentioning

confidence: 99%

Low‐Temperature Alkane CH Bond Activation by Zeolites: An In Situ Solid‐State NMR H/D Exchange Study for a Carbenium Concerto

Haouas

Fink

Taulèlle

et al. 2010

Chemistry A European J

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Isotopic H/D exchange has been monitored by in situ MAS NMR spectroscopy of 2-[D(14)]methylpentane with H-USY to probe the controversy over the alkane conversion mechanism. The probe molecule has distinct exchangeable sites with different accessibility to the zeolite surface. In the early stages of the process, the regioselectivity of exchange demonstrates that the slow step of the mechanism is controlled by a carbenium ion intermediate. At a later stage of exchange, intramolecular hydride migrations, typical of carbenium chemistry, replace D by H also on other carbon atoms, resulting in a loss of regioselectivity. Therefore, the first and the subsequent steps of the H/D exchange proceed at this temperature through a carbenium intermediate species.

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“…(7). The chain initiation is the formation of a carbocation, the cyclopentyl or cyclohexyl cation from 3 or 4.…”

Section: Tables 3 and 4 From D O T S Of Inmentioning

confidence: 99%

“…The results from cyclobutane thus resemble closely the earlier finding of Otvos rt n l . (7), reported in 195 1, that the treatment of isobutane with I-d gave rise to the tert-butyl cation, and that exchange occurred with all 9 a-hydrogens. It is of interest to ascertain what would take place when cycloalkanes other than the small ring hydrocarbons are treated with acids under similar conditions.…”

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Isotopic exchanges in the treatment of cyclopentane or cyclohexane with some deuterated or tritiated acids

Lee¹,

Ko²

1981

Can. J. Chem.

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The exchange between the H atoms of cyclopentane (3) or cyclohexane (4) and the labeled acid protons of CF3SO3D (2-d), [3H]CF3SO3H (2-t), [3H]H2SO4 (1-t), or ZnCl2−[3H]HCl (5-t) has been investigated. Results from the treatment of 3 or 4 with 2-d at 0° or 20 °C, respectively, gave rise to polydeuterated cycloalkanes, indicating that all H atoms of 3 or 4 could be involved in the exchange. The rates of incorporation of the T-label into the hydrocarbon layer from the tritiated acids were found to be directly related to acid strength. After treatment of 3 or 4 with 2-t, quenching of the acid layer and analysis by isotope dilution showed the presence of cyclopentanol or cyclohexanol. A carbocationic chain mechanism for the exchange, as well as the mechanism for the formation of the cycloalkyl cation from the cycloalkane, are discussed.

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The Behavior of Isobutane in Concentrated Sulfuric Acid¹

Cited by 78 publications

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Die Renaissance des H/D‐Austausches

Die Renaissance des H/D‐Austausches

Low‐Temperature Alkane CH Bond Activation by Zeolites: An In Situ Solid‐State NMR H/D Exchange Study for a Carbenium Concerto

Isotopic exchanges in the treatment of cyclopentane or cyclohexane with some deuterated or tritiated acids

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The Behavior of Isobutane in Concentrated Sulfuric Acid1

Cited by 78 publications

References 0 publications

Die Renaissance des H/D‐Austausches

Die Renaissance des H/D‐Austausches

Low‐Temperature Alkane CH Bond Activation by Zeolites: An In Situ Solid‐State NMR H/D Exchange Study for a Carbenium Concerto

Isotopic exchanges in the treatment of cyclopentane or cyclohexane with some deuterated or tritiated acids

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The Behavior of Isobutane in Concentrated Sulfuric Acid¹