Abstract
When 1-hexene was adsorbed by Cr3+-montmorillonite at room temperature, all evidence of C=C(str) vibrations was lost. Protonation of the alkene occurred, and the secondary carbocation formed was bound at a site on the primary coordination sphere of the interlayer cation. Some of the hydrogen atoms of these primary-sphere water molecules were involved in strong hydrogen bonds to the silicate sheets, whereas others did not form such bonds, but were free and directed into the interlayer space. These latter hydrogen atoms were labile and protonated the alkene molecules.
Резюме
После адсорбции 1-гексена на Cr3+-монтмориллоните при комнатной температуре, исчезло все доказательство колебаний С=С (растягиваний). Появлялось протонирование алкенов, а вторичный образованный катион углерода был связан в основной координационной сфере межслойных катионов. Некоторые атомы водорода молекул воды этих основных сфер были связаны сильными водородными связями с силикатовыми слоями, в то время, как другие атомы не образовывали таких связей, а оставались свободными и направлялись в межслойное пространство. Эти свободные атомы водорода являлись неустойчивыми и протонировали молекулы алкенов. [E.G.]
Resümee
Wenn 1-Hexen bei Raumtemperatur an Cr3+-Montmorillonit adsorbiert wird, so gibt es für C=C(str)-Schwingungen keinen Hinweis mehr. Protonierung der Alkene trat ein, und die auftretende sekundäre Carbonierung war an eine Stelle der primären Koordinationshülle des Zwischenschichtkations gebunden. Einige der Wasserstoffatome dieser primären Wassermolekülhülle waren durch eine starke Wasserstoffbindung an die Silikatschicht gebunden, während andere keine derartige Bindung aufwiesen sondern ungebunden und in den Zwischenschichtraum ausgerichtet waren. Diese letzteren Wasserstoffatome waren labil und protonierten die Alkenmoleküle. [U.W.]
Résumé
Lorsque l’hexène-1 a été adsorbée par la montmorillonite-Cr3+ à température ambiante, toute evidence de vibrations C=C(str) a été perdue. La protonation de l’alkalène s’est produite, et la carbocation secondaire formée a été liée à un site sur la sphère de coordination primaire de cation intercouche. Certains atomes d’hydrogène de ces molécules d’eau de sphère primaire ont été impliqués dans de très fortes liaisons d’hydrogène avec les feuillets silicates, tandis que d’autres n’ont pas formé de telles liaisons, mais étaient libres et se sont dirigés vers l’espace intercouche. Ces derniers atomes d’hydrogène étaient labiles et ont protonaté les molécules alkalènes. [D.J.]
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Adams, J.M., Clapp, T.V. Infrared Studies of 1-Hexene Adsorbed onto Cr3+-Exchanged Montmorillonite. Clays Clay Miner. 33, 15–20 (1985). https://doi.org/10.1346/CCMN.1985.0330102
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DOI: https://doi.org/10.1346/CCMN.1985.0330102