Physical Sciences and Mathematics Commons^™

A Solvent-Free Oxidation Of Alcohols In An Organic Laboratory, John Esteb, Michael Schelle, Anne Wilson

John Esteb

An oxidation experiment for a first-year organic chemistry class is presented. This oxidation utilizes a solid mixture of CuSO4•5H2O and KMnO4 prepared by mortar and pestle. The oxidations take place under solvent-free conditions and near quantitative yields are obtained for the reactions. Thin-layer chromatography is used to monitor the progress of the reaction. This experiment provides for the simple oxidation of a secondary alcohol to a ketone using a relatively nontoxic oxidizing agent under solvent-free conditions.

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A Convenient One-Pot, Organoaluminum Mediated Vinylsilane Synthesis From Non-Enolizable Ketones Via The Peterson Protocol, Man Lung Kwan, Merle Battiste

Man Lung Desmond Kwan

Vinylsilanes serve as convenient vinyl anion equivalents which have gained popularity over decades. A variety of non-enolizable aromatic ketones are converted to the corresponding vinylsilanes in a one-pot procedure involving the addition of (trimethylsilylmethyl)lithium to aromatic ketones followed by addition of diethylaluminum chloride and then small amounts of water. Halide and alkoxide substituents are tolerated, and this trans-stereoselective (broad generalization; the most sterically bulky group on the double bond is trans to the trimethylsilyl group) reaction affords vinylsilanes in good yield.

Kinetics Of Substitution Of Weakly Coordinating Nitrate By Chloride In (Η5-Cp)Ru(Co)(Er3)Ono2 (Er3 = Asph3, Pph3, P(P-Anisyl)3, Pph2(O-Anisyl), P(Oph)3) In Dichloromethane., Minhton Cao, Liem Do, Norris Hoffman, Man Lung Kwan, Julie Little, J. Mcgilvray, Christopher Morris, Bjorn Söderberg, Andrzej Wierzbicki, Thomas Cundari, Charles Lake, Edward Valente

Man Lung Desmond Kwan

The d6 complexes of formula (η5-Cp)Ru(CO)(ER3)ONO2, where ER3 = AsPh3, PPh3, P(p-anisyl)3, PPh2(o-anisyl), and P(OPh)3, were prepared by reaction of their chloro analogues with AgNO3 in CH2Cl2. They underwent moderately slow substitution of the relatively weakly coordinating nitrate by chloride in dry CH2Cl2 in the presence of excess [N(PPh3)2+]Cl-. A kinetics study showed the reaction to be first order in nitrato complex and independent of chloride salt concentration under pseudo-first-order conditions. First-order rate constants for nitrate metathesis follow the trend P(OPh)3 < PPh3 < P(p-anisyl)3 < AsPh3 PPh2(o-anisyl), with k1 at 25 °C for the first four in the series from 1.4 to 4.4 × 10-5 s-1. Activation parameters for conversion of (η5-Cp)Ru(CO)(AsPh3)ONO2 to its chloride are ΔH‡ = 17(2) kcal/mol and ΔS‡ = −21(5) eu. Even use of a slightly moist solvent increased the rate of nitrate metathesis by 20−30% without changing the form of the rate law. The complex containing PPh2(o-anisyl) was approximately 2 orders of magnitude more reactive (k1 = 4.9 × 10-3 s-1). A likely explanation is stabilization of a coordinatively unsaturated intermediate by weak coordination of the potentially chelating o-OMe group. A mechanism entailing rate-limiting conversion of the neutral nitrato complex into a coordinatively unsaturated ion-paired species is consistent with this set of data. Semiempirical calculations (PM3(tm)), which model the structures of complexes in these systems quite well, supported such behavior. X-ray crystal structures were determined for the AsPh3 nitrato and chloro complexes and for the PPh3 chloro complex.

Stereoselective One-Pot Synthesis Of Vinylsilanes From Aromatic Aldehydes, Man Lung Kwan, Chiu Yeung, Kerry Breno, Kenneth Doxsee

Man Lung Desmond Kwan

Vinylsilanes serve as convenient vinyl anion equivalents, but procedures for their stereoselective synthesis from aldehydes are scarce. A variety of aromatic aldehydes are converted to the corresponding vinylsilanes in a one-pot procedure involving the addition of (trimethylsilylmethyl)lithium to the aldehyde followed by treatment with Cp2TiCH2·AlMe2Cl (‘Tebbe's reagent’). Halide and alkoxide substituents are tolerated, and (E)-vinylsilanes are formed exclusively in good yield.

Synthesis Of [15n,15n‘]-N,N,N‘,N‘-Tetramethyl- Ethylenediamine And Its Use In Solvation Studies Of [6li]-N-Butyllithium., Delia Waldmüller, Barbara Kotsatos, Michael Nichols, Paul Williard

Michael A Nichols

No abstract provided.

Purification And Crystallization Of Cyclin-Dependent Kinase Inhibitor P21., D. Mayrose, Michael Nichols, Y. Xiong, H. Ke

Michael A Nichols

p21, a universal inhibitor of mammalian cyclin-dependent kinases (CDK), regulates cell cycle progression by forming various distinct protein complexes with cyclins, CDKs, and the proliferating cell nuclear antigen. We have overexpressed recombinant human p21 in E. coli and purified active p21 to near homogeneity on a large scale. Crystals of recombinant p21 have been grown in the space group P2(1) a = 157.4, b = 152.7, c = 90.6 A, and beta = 92.7 degrees. The diffraction data of the recombinant p21 have been collected to 2.5 and 3.5 A resolution for the native crystal and two heavy atom derivatives …

6li And 15n Nuclear Magnetic Resonance Studies Of Mixed Alkali Metal Cation Hexamethyldisilazide Bases, Michael Nichols, Delia Waldmüller, Paul Williard

Michael A Nichols

No abstract provided.

Hexameric Lithium Phenolate: Crystal Structures And Lithium-7 Quadrupole Coupling In Solid And Solution Phases., Lloyd Jackman, Deniz Cizmeciyan, Paul Willard, Michael Nichols

Michael A Nichols

No abstract provided.

Solid-State Structures Of N-Butyllithium-Tmeda, -Thf, And -Dme Complexes., Michael Nichols, Paul Williard

Michael A Nichols

No abstract provided.

Synthesis And Structure Of A Product, Formed During Dna Nicking With A Cyclometallated Nuclease, Consisting Of An Adenine Bridging Two Palladium(Ii) Complexes., J. Suggs, Michael Du\Ube, Michael Nichols

Michael A Nichols

Journal of the Chemical Society, Chemical Communications

Γ-Aminobutyric Acid, Catecholamine And Indoleamine Determinations From The Same Brain Region By High-Performance Liquid Chromatography With Electrochemical Detection., T. Champney, W. Hanneman, Michael Nichols

Michael A Nichols

A new procedure for the measurement of γ-aminobutyric acid, norepinephrine, dopamine, serotonin and 5-hydroxyindoleacetic acid from the same brain region was developed. In general, two separate high-performance liquid chromatographic runs were performed, one for the γ-aminobutyric acid determination and one for the determination of the monoamines. The electrochemical detection of γ-aminobutyric acid was determined by a new procedure that utilized a small aliquot of the brain sample prepared for monoamine measurement. This assay was linear and parallel between 6 and 200 ng per 20-μl injection with 5-aminovaleric acid utilized as an internal standard. Inter-assay variability averaged 5% throughout the assay …

Structural Characterization Of Mixed Alkali Metal Bis(Trimethylsilyl)Amide Bases., Paul Williard, Michael Nichols

Michael A Nichols

No abstract provided.

Chelation Of 2-Substituted 1-Lithoxides: Structural And Energetic Factors Of Relevance To Synthetic Organic Chemistry., Michael Nichols, Andrew Mcphail, Edward Arnett

Michael A Nichols

No abstract provided.

Structural And Energetic Evidence For Oxygen-Lithium-Nitrogen Chelation In A Model For Asymmetric Induction., Edward Arnett, Michael Nichols, Andrew Mcphail

Michael A Nichols

No abstract provided.

Structure-Energy Relations For The Aldol Reaction In Nonpolar Media., Edward Arnett, Franklin Fisher, Michael Nichols, Anthony Ribeiro

Michael A Nichols

No abstract provided.

Thermochemistry Of A Structurally Defined Aldol Reaction., Edward Arnett, Franklin Fisher, Michael Nichols, Anthony Ribeiro

Michael A Nichols

No abstract provided.