Full metadata record
DC Field | Value | Language |
---|---|---|
dc.contributor.author | 권동숙 | * |
dc.contributor.author | 엄익환 | * |
dc.date.accessioned | 2018-06-02T08:15:42Z | - |
dc.date.available | 2018-06-02T08:15:42Z | - |
dc.date.issued | 1997 | * |
dc.identifier.issn | 0022-3263 | * |
dc.identifier.other | OAK-16696 | * |
dc.identifier.uri | https://dspace.ewha.ac.kr/handle/2015.oak/244620 | - |
dc.description.abstract | Second-order rate constants have been measured spectrophotometrically for the reactions of p-nitrophenyl acetate (PNPA) with three α-effect nucleophiles, benzohydroxamate (BHA-), p- methylbenzohydroxamate (MBHA-), and p-methyl-N-methylbenzohydroxamate (M2BHA-), and a corresponding normal nucleophile, m-chlorophenoxide (ClPhO-), in MeCN-H2O mixtures of varying compositions at 25.0 °C. The reactivity of ClPhO- and M2BHA- toward PNPA decreases upon additions of MeCN into the reaction medium up to near 30-40 mol % MeCN and is followed by a gradual increase upon further additions of MeCN. BHA- and MBHA- also exhibit initial rate decreases upon the addition of MeCN up to near 40 mol % MeCN. However, unlike the ClPhO- and M2BHA- systems, the rate enhancement beyond 40 mol % MeCN is negligible for the BHA- and MBHA- systems. The present benzohydroxamates exert a large α-effect in H2O. Interestingly, BHA- and MBHA- show a decreasing α-effect trend with increasing mol % MeCN, while M2BHA- exhibits an increasing α-effect trend, indicating that the magnitude of the α-effect is significantly solvent dependent. Based on the results of the kinetic study and relative basicity measurements, the decreasing α-effect trend shown by BHA- and MBHA- has been attributed to an equilibrium shift of these hydroxamates (I) toward their isomeric structures (II or III) upon the addition of MeCN. The solvent dependent α-effect has led a conclusion that the solvent effect on the α-effect is significant; however, the ground state contribution is not solely responsible for the α-effect in the present system. | * |
dc.language | English | * |
dc.title | Effect of Solvent on the α-Effect: Nucleophilic Substitution Reactions of p-Nitrophenyl Acetate with m-Chlorophenoxide and Benzohydroxamates in MeCN-H2O Mixtures of Varying Compositions | * |
dc.type | Article | * |
dc.relation.issue | 17 | * |
dc.relation.volume | 62 | * |
dc.relation.index | SCI | * |
dc.relation.index | SCIE | * |
dc.relation.index | SCOPUS | * |
dc.relation.startpage | 5939 | * |
dc.relation.lastpage | 5944 | * |
dc.relation.journaltitle | Journal of Organic Chemistry | * |
dc.identifier.scopusid | 2-s2.0-0000754039 | * |
dc.author.google | Um I.-H. | * |
dc.author.google | Yoon H.-W. | * |
dc.author.google | Lee J.-S. | * |
dc.author.google | Moon H.-J. | * |
dc.author.google | Kwon D.-S. | * |
dc.contributor.scopusid | 권동숙(7103159894;16165739700) | * |
dc.contributor.scopusid | 엄익환(7006725706;6506759437) | * |
dc.date.modifydate | 20240423081003 | * |