- Anionic Micellar Effects on the Benzophenone-sensitized Photolysis of N-(1-Naphthoyl)-N-phenyl-O-benzoylhydroxylamine
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Most important property of compartmentalized liquids such as micelles is that they have an ability to concentrate guest molecules into relatively small effective volumes and then to promote the re-encounter of such molecules. This property also makes mice
- Kaneko, Tsuyoshi,Kubo, Kanji,Sakurai, Tadamitsu
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p. 2757 - 2774
(2007/10/03)
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- Tertiary Amine-Catalyzed Acyl Group Exchange Reaction of N,O-Diacyl-o-aminophenols. Its Mechanism and Factors Determining the Relative Stability of Acyl Exchanged Isomer Pairs
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Acyl substituent effects on the equilibrium and rate constants for the acyl group exchange reactions of various N,O-diacyl-o-aminophenols have been investigated in solvents with different polarities.It was found that the relative stability of acyl exchanged isomer pairs is determined solely by the inductive effect of acyl groups, provided that the steric hindrance of acyl substituents bonded to amide nitrogen affects the stability to the same extent.The importance of steric hindrance exerted by a bulky acyl group in determining the relative stability was demonstrated by analyzing the correlation between the standard free energy change (ΔG0) and pKa, which were used as the measure of the relative stability of isomer pairs and of the electron-with drawing ability of acyl groups, respectively.On the other hand, the logarithms of catalytic rate constants for the acyl migration reactions were correlated well to the pKa values.In addition to this finding, a large negative value of activation entropy (ΔS=-160 J K-1 mol-1) and the Broensted coefficient β of 0.65 for the reaction of N,O-(acetyl)-(1-naphthoyl) pair of N,O-diacyl-o-aminophenol provide a definitive evidence for the rate-determining proton transfer from this derivative to amine catalyst in the transition state.
- Sakurai, Tadamitsu,Kojima, Shuichi,Inoue, Hiroyasu
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p. 3141 - 3148
(2007/10/02)
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- The Photolysis of N,O-Diacyl-N-phenylhydroxylamines
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The photochemical decomposition of the title compounds yielded the rearrangement products derived from 1,3- and 1,5-aroyloxyl migrations in addition to the fragmentation products typical of the aroyloxyl and amido radicals, while only 1,3-aroyloxyl migration was observed on thermolysis.The results of crossover experiments indicate an intramolecular rearrangement, probably involving homolysis of the N-O bond in the excited states.Triplet quenching studies demonstrate that the rearrangement and fragmentation proceed exclusively via the first excited singlet state.No formation of the rearrangement products on triplet sensitization was expl ained on the basis of the spin multiplicity effects on a radical-radical recombination process within a solvent cage.
- Sakurai, Tadamitsu,Yamamoto, Hirofumi,Yamada, Shuichi,Inoue, Hiroyasu
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p. 1174 - 1181
(2007/10/02)
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