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Kinetics and mechanistic studies of molybdenum(2) oxygen(3) (diethyl dtc)(2) (THF)(2) iodine(2)
Title
Kinetics and mechanistic studies of molybdenum(2) oxygen(3) (diethyl dtc)(2) (THF)(2) iodine(2).
Creator
Abburi, Chakravarthi., Florida Atlantic University, Baird, Donald M.
Abstract/Description
A study of the kinetic behavior of the oxygen atom transfer reaction of Mo2o3 (Et2dtc)2 (THF) 2I2, (I), with a variety of derivatives of pyridine N-oxides has been performed. The reaction behaves in pseudo-first-order fashion under conditions of excess N-oxide. Plots of kobs vs. [N-oxide] do not give straight lines, while plots of 1/kobs vs. 1/[N-oxide] are linear. The rate constant k is taken as the inverse of the slope of this latter plot. There is a marked dependence of the rate on the...
Show moreA study of the kinetic behavior of the oxygen atom transfer reaction of Mo2o3 (Et2dtc)2 (THF) 2I2, (I), with a variety of derivatives of pyridine N-oxides has been performed. The reaction behaves in pseudo-first-order fashion under conditions of excess N-oxide. Plots of kobs vs. [N-oxide] do not give straight lines, while plots of 1/kobs vs. 1/[N-oxide] are linear. The rate constant k is taken as the inverse of the slope of this latter plot. There is a marked dependence of the rate on the functional group in the 4-position of the pyridine ring with the relative rates -CH3 > -H > -Cl > -CN. The above observations can be used to support a mechanism in which a rapid pre-equilibrium, with a large equilibrium constant, is followed by a rate-determining breaking of the Mo-O-Mo bridge.
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Date Issued
1992
PURL
http://purl.flvc.org/fcla/dt/14828
Subject Headings
Enzyme kinetics, Molybdenum enzymes, Chemical kinetics
Format
Document (PDF)
Development and applications of nucleophile assisting leaving groups (NALGs) with Titanium (IV) and Grignard reagents
Title
Development and applications of nucleophile assisting leaving groups (NALGs) with Titanium (IV) and Grignard reagents.
Creator
Li, Songye., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
Abstract/Description
We report here the development of very efficient aryl- and quinolinyl- sulfonate based leaving groups, termed Nucleophile Assisting Leaving Groups (NALGs), which substantially accelerate the rate of nucleophilic substitution reactions with metal halides. Detailed synthesis and kinetics study are described herein. Our synthesized NALGs have shown great reactivity towards poor nucleophiles and/or substrates traditionally considered too hindered to undergo nucleophilic attack. The abundant...
Show moreWe report here the development of very efficient aryl- and quinolinyl- sulfonate based leaving groups, termed Nucleophile Assisting Leaving Groups (NALGs), which substantially accelerate the rate of nucleophilic substitution reactions with metal halides. Detailed synthesis and kinetics study are described herein. Our synthesized NALGs have shown great reactivity towards poor nucleophiles and/or substrates traditionally considered too hindered to undergo nucleophilic attack. The abundant existence of halide, azide and amine in natural products demands new synthetic pathway. To fulfill this requirement, new mild stereoretentive halogenations (chlorination, bromination and iodination) reactions have also been developed for secondary cyclic alcohols using NALGs involving titanium (IV) reagents. The novel methodology can be extended to Azidation reactions as well with titanium (IV) azide, in which Ti (N3)4 is the first time being engaged in organic synthesis. Beased on the NALGs theory we discover the chlorosulfite can be a simplest NALG and applied as the intermediate in mild one-pot stereoretentive halogenations (chlorination and bromination) using titanium (IV) halides as catalysts or stoichiometric reagents. These reactions were found to be particularly efficient for cyclic alcohols. Finally, an efficient mild bromination and iodination reaction for primary and secondary alcohols with Grignard reagents is also reported. This reaction exhibits the generality with substrates with various leaving groups. The important features of this reaction are that, for the first time, bromide formation using Grignard reagents without the Cu (I) catalysts.
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Date Issued
2011
PURL
http://purl.flvc.org/FAU/3183130
Subject Headings
Chemical kinetics, Chemical reaction, Condition and laws of, Organic compounds, Synthesis, Organotransition metal compounds, Intermediates (Chemistry), Organic reaction mechanisms
Format
Document (PDF)
Global feedback in hierarchical motion pattern formation
Title
Global feedback in hierarchical motion pattern formation.
Creator
Brownlow, Stacey W., Florida Atlantic University, Hock, Howard S., Charles E. Schmidt College of Science, Department of Psychology
Abstract/Description
An array of four motion quartets (stimuli for which either horizontal or vertical motion is perceived depending on quartet aspect ratio) is arranged in a diamond configuration such that two global motion patterns are formed: (1) Rotation---alternating counterclockwise and clockwise motion is perceived, and (2) Parallel path motion---the perceived motions of all the elements are simultaneously horizontal or simultaneously vertical. The perception of rotation resulted in global feedback that...
Show moreAn array of four motion quartets (stimuli for which either horizontal or vertical motion is perceived depending on quartet aspect ratio) is arranged in a diamond configuration such that two global motion patterns are formed: (1) Rotation---alternating counterclockwise and clockwise motion is perceived, and (2) Parallel path motion---the perceived motions of all the elements are simultaneously horizontal or simultaneously vertical. The perception of rotation resulted in global feedback that biases the motion perceived for an individual component motion quartet to be more consistent with rotation than aspect ratio. Stronger rotation produced greater bias. Under certain conditions, the feedback-induced bias occurred even though global rotation was not perceived. The results were interpreted in the context of neurophysiological evidence regarding neurons in Areas MT and MSTd, and a dynamical theory of motion pattern formation (Hock, Schoner & Giese, 2003; Nichols, Hock & Schoner, 2006).
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Date Issued
2006
PURL
http://purl.flvc.org/fcla/dt/13371
Subject Headings
Motion perception (Vision)--Mathematical models, Visual pathways, Neurophysiology, Nonlinear chemical kinetics
Format
Document (PDF)
Hurst analysis applied to the study of single calcium-activated potassium channel kinetics
Title
Hurst analysis applied to the study of single calcium-activated potassium channel kinetics.
Creator
Liebovitch, Larry S., Figueiroa, Josed N., Nogueira, Romildo A., Varanda, Wamberto A.
Date Issued
2000-10-07
PURL
http://purl.flvc.org/FAU/165249
Subject Headings
Ion channels-Mathematical models, Memory, Chemical kinetics, Calcium channels, Fractals, Markov processes, Leydig cells, Molecular biology--Statistical methods
Format
Document (PDF)