View : 462 Download: 0

Full metadata record

DC Field Value Language
dc.contributor.author엄익환-
dc.date.accessioned2017-03-01T01:03:43Z-
dc.date.available2017-03-01T01:03:43Z-
dc.date.issued2017-
dc.identifier.issn0008-4042-
dc.identifier.issn1480-3291-
dc.identifier.otherOAK-20225-
dc.identifier.urihttps://dspace.ewha.ac.kr/handle/2015.oak/234621-
dc.description.abstractPseudo-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.languageEnglish-
dc.publisherCANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS-
dc.subjectalkali metal ion catalysis and inhibition-
dc.subjectalkaline ethanolysis-
dc.subjectelectrophilic centre-
dc.subjectreaction mechanism-
dc.subjectYukawa-Tsuno equation-
dc.titleAlkali 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.typeArticle-
dc.relation.issue1-
dc.relation.volume95-
dc.relation.indexSCIE-
dc.relation.indexSCOPUS-
dc.relation.startpage45-
dc.relation.lastpage50-
dc.relation.journaltitleCANADIAN JOURNAL OF CHEMISTRY-
dc.identifier.doi10.1139/cjc-2016-0378-
dc.identifier.wosidWOS:000392108700007-
dc.author.googleUm, Ik-Hwan-
dc.author.googleKang, Ji-Sun-
dc.author.googleDust, Julian M.-
dc.contributor.scopusid엄익환(7006725706;6506759437)-
dc.date.modifydate20210915144022-
Appears in Collections:
자연과학대학 > 화학·나노과학전공 > Journal papers
Files in This Item:
There are no files associated with this item.
Export
RIS (EndNote)
XLS (Excel)
XML


qrcode

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE