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Showing 1 to 10 of 10 for “"substituent effect"”.
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Progress towards a highly efficient and accurate platform for enantiomeric excess determination
… based multicomponent assembly. To start, the substituent effect of the zinc multicomponent dynamic assembly for secondary chiral alcohol ee determination was investigated. A new assembly with a higher dynamic range and smaller error was observed. Additionally, potential cooperative binding to …
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New Methods for the Formation of Methyl Bearing Stereogenic Centers via Methylketene Dimerization and Free Radical Additions to Allyl Bromides
… and chiral Lewis acids. Additionally, substituent effect on the rates of this reaction were examined closely and found to be comparable to similar, previously examined systems. The synthetic utility, magnitude and scope of this reaction are discussed.
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KINETICS OF THE METHYL-IODIDE CATALYZED AND AUTOCATALYZED ARBUZOV REARRANGEMENT (METHOXYPHOSPHONIUM, CONDUCTIVITY, PHOSPHORUS NMR)
… same compounds were measured by ('31)P nmr. The substituent effect ((rho)(,I)) for the reactions was determined by correlation of the kinetic data with the sum of the Taft inductive parameters ((sigma)(,I)) of the substituents on phosphorus. The (rho)(,I) values for the two steps of the …
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Kinetic Studies of the Sulfoxidation of Aryl Methyl Sulfides by Trans-Dioxoruthenium(VI) Porphyrin Complexes
… studied by rapid stopped-flow spectroscopy. The substituent effect in sulfides and in dioxoruthenium(VI) complexes were also kinetically investigated. The low-reactive <i>trans</i>-dioxoruthenium(VI) porphyrin complexes (3a-b) were synthesized from the oxidation of their carbonylruthenium(II) …
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Unusual Electron Transfer Rate Effects due to Pyridyl Ring Substituents and Trace Group VIII b Hexacyano Complexes as Added Salts
… indicate that the origin of the phenyl substituent effect is in the enthalpic portion of the free-energy of activation. One explanation is that the reorganizational barrier λ might be significantly lower for the 3-Phpy and 4-Phpy complexes, or it could be that energetically-favorable p-p …
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Artificial Transmembrane Signalling and Cooperativity in H-Bonded Networks
… hydroxyl groups. However, the magnitude of this effect is difficult to quantify experimentally. The aim of the second project was to develop a systematic structure-activity approach to the quantification of cooperativity. A series of phenol oligomers containing intramolecular hydrogen bonds was …
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Studies Related to the Alternating Copolymerization of Substituted Stilbenes
… study was undertaken to understand the methyl substituent effect on copolymerization rates. Methyl substituted stilbene-maleic anhydride copolymer compositions were determined by quantitative ¹³C 1D NMR. SEC measurements showed the weight average molecular weights of these copolymers vary from …
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Mass spectrometry of substituted benzils
… of the substituted benzoyl ions exhibit substituent effects correlatable with the Hammett σ, but no substituent effect is demonstrated for the unsubstituted benzoyl. Loss of CO by the benzoyl ion does not appear to involve substituent effects but required 2.5-4.0 eV excess energy above …
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Asymmetric Synthesis of Homotropinone and Tropane Alkaloids using Enantiopure Sulfinimines and the Synthesis and Applications of Methanoprolines
… were synthesized stereoselectively to study the substituent (H, OH, or F) effect on amide conformational preferences. A nucleophilic displacement synthetic route was devised to prepare highly functionalized 5(6)-anti-substituted-methanopyrrolidines from N-benzyl-2-azabicyclo[2.1.1]hexylbromide(s) …