Full metadata record
DC Field | Value | Language |
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dc.contributor.author | 엄익환 | - |
dc.date.accessioned | 2017-03-01T01:03:43Z | - |
dc.date.available | 2017-03-01T01:03:43Z | - |
dc.date.issued | 2017 | - |
dc.identifier.issn | 0008-4042 | - |
dc.identifier.issn | 1480-3291 | - |
dc.identifier.other | OAK-20225 | - |
dc.identifier.uri | https://dspace.ewha.ac.kr/handle/2015.oak/234621 | - |
dc.description.abstract | Pseudo-first-order rate constants (k(obsd)) were measured for nucleophilic substitution reactions of O-Y-substituted-phenyl O-phenyl thionocarbonates (4a-4h) with alkali metal ethoxides (EtOM, M = Li, Na, or K) in anhydrous ethanol at 25.0 +/- 0.1 degrees C. Plots of k(obsd) vs. [EtOM] exhibited upward curvature for the reaction of O-4-nitrophenyl O-phenyl thionocarbonate (4a) with EtOK in the presence of 18-crown-6-ether (18C6), but showed downward curvature for the reaction with EtOLi, indicating that the reaction is catalyzed by the 18C6-crowned K+ ion, but is inhibited by Li+ ion. The k(obsd) values were dissected into k(EtO)- and k(EtOM), the second-order rate constant for the reaction with dissociated EtO- and ion-paired EtOM, respectively. The reactivity of EtOM toward 4a increases in the order EtOLi < EtONa < EtO- < EtOK < EtOK/18C6, which is in contrast to that reported previously for the corresponding reaction of 4-nitrophenyl phenyl carbonate (a C=O analogue of 4a), e.g., EtO- approximate to EtOK/18C6 < EtOLi < EtONa < EtOK. The reaction mechanism, including the transition-state model and the origin of the contrasting reactivity patterns found for the reactions of the C=O and C=S compounds, are discussed. | - |
dc.language | English | - |
dc.publisher | CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS | - |
dc.subject | alkali metal ion catalysis and inhibition | - |
dc.subject | alkaline ethanolysis | - |
dc.subject | electrophilic centre | - |
dc.subject | reaction mechanism | - |
dc.subject | Yukawa-Tsuno equation | - |
dc.title | Alkali metal ion catalysis and inhibition in alkaline ethanolysis of O-Y-substituted-phenyl O-phenyl thionocarbonates: contrasting M+ ion effects upon changing electrophilic centre from C=O to C=S | - |
dc.type | Article | - |
dc.relation.issue | 1 | - |
dc.relation.volume | 95 | - |
dc.relation.index | SCIE | - |
dc.relation.index | SCOPUS | - |
dc.relation.startpage | 45 | - |
dc.relation.lastpage | 50 | - |
dc.relation.journaltitle | CANADIAN JOURNAL OF CHEMISTRY | - |
dc.identifier.doi | 10.1139/cjc-2016-0378 | - |
dc.identifier.wosid | WOS:000392108700007 | - |
dc.author.google | Um, Ik-Hwan | - |
dc.author.google | Kang, Ji-Sun | - |
dc.author.google | Dust, Julian M. | - |
dc.contributor.scopusid | 엄익환(7006725706;6506759437) | - |
dc.date.modifydate | 20230411105538 | - |