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AFFINITY ENRICHMENT AND MASS SPECTROMETRIC QUANTITATION OF PROTEIN CARBONYLSNarayanasamy, Suresh 01 January 2014 (has links)
The importance of the role of oxidative stress in aging and numerous age-related diseases has become undeniable due to enormous weight of supporting evidence from the field of free radical biology. One of the most prominent oxidative modifications of proteins is the introduction of carbonyl groups. As with oxidative stress, protein carbonylation has been correlated with various disease states and natural aging. While protein carbonyls are relatively stable, reproducible detection and modification site localization are still challenging. This thesis details attempts to improve the analytical methodology used for the identification and quantitation of carbonylated proteins. We have studied the impact of exogenous and endogenous methods for increasing the flux of the progenitor reactive oxygen species, the superoxide radical anion, in Drosophila melanogaster using protein carbonylation measurements. Furthermore, we have applied the same methodology to plasma and serum obtained from trauma patients. Superoxide flux was manipulated first by administering Paraquat to increase generation rates throughout the cell and second through RNA interference knockdown of Mn or mitochondrial superoxide dismutase (Sod2) to decrease destruction rates in mitochondria. Protein carbonylation was measured since carbonyls are not present in the twenty canonical amino acids and are amenable to labeling and enrichment strategies (biotin hydrazide was used for labeling and streptavidin bead-immobilization for enrichment). On-bead digestion was used to release carbonylated protein peptides, which were then subjected to the iTRAQ mass spectrometry-based proteomics approach to obtain Paraquat-exposed and Sod2 knockdown versus control carbonylated protein relative abundance ratios. Western blotting and biotin quantitation assay approaches were also investigated. Considering the whole set of detected carbonylated proteins, lipid droplet and mitochondrial proteins were found to be particularly prevalent. By both western blotting and proteomics, Paraquat exposure resulted in a greater global increase in carbonylation than Sod2 knockdown. However, the Sod2 knockdown dataset included an interesting outlier, cytochrome c oxidase subunit Vb, which could shed light on the mechanism of superoxide generation or the Sod2 knockdown phenotype. An alternative to the iTRAQ quantitation approach, the label-free “Spectral counting” technique was also investigated, using the Paraquat-exposed versus control Drosophila melanogaster samples. Thus, we investigated the correlation between spectral count and iTRAQ-based quantitation. We observed good reproducibility for the iTRAQ approach but not for spectral counting. Comparing mitochondrial relative protein abundances, we found only a weak positive correlation between these two approaches. Discovery proteomics approaches that aim to identify biomarkers or signaling pathways associated with human diseases have gained much attention in recent years. Due to the minimally invasive nature of collecting blood, plasma proteomics has become a common means of studying the entire human proteome, even though cellular proteins leaking into the circulatory system are present at very low concentrations. Severe blunt trauma produces significant changes in leukocyte mRNA levels, corresponding to changes in expression for >80% of human genes. Thus, the early leukocyte genomic response involves simultaneously increasing expression of genes involved in the systemic inflammatory, innate immune, and compensatory anti-inflammatory responses, as well as with suppressing genes involved in adaptive immunity. Inflammation and oxidative stress are often correlated. Thus we analyzed the carbonylated protein proteome at multiple time points in the blood of patients that had endured traumatic injuries. First, temporal changes in carbonylated protein concentrations were measured. Second, the ProteoMiner affinity-ligand strategy was added to the procedure to increase proteome coverage through the depletion of high-abundance plasma proteins. This improved method resulted in the identification of greater numbers of low-abundance proteins. Since the sample size (n=2) was very small, no biological conclusion could be drawn; however, we have shown that measurements of changes in the carbonylated protein proteome over time are possible by this method. The hope is that protein carbonylation biomarkers could someday aid in predicting patient outcomes in clinical settings.
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Direct Determination of Pentachlorophenol by Differential Pulse PolarographyWade, Albert L. 01 January 1978 (has links)
Concern over environmental contamination leading to the introduction of pentachlorophenol into human and animal systems has resulted in the need for a rapid and direct method for determining trace concentrations of this highly toxic compound. A direct electrochemical procedure has been developed for determining trace conccentrations of this phenol dovm to 0.27 ppm. This method uses the electrochemical techniques of differential pulse polarography at the dropping mercury electrode, and differential pulse voltammetry at the carbon paste electrode to reduce pentachlorophenol for this determination. Cyclic voltammetry at the hanging mercury drop electrode has been used to characterize the reaction behavior of pentachlorophenol. Two voltammetric peaks were found with this procedure. A voltammetric peak at -0.4 volts versus Ag/AgCl exhibited the adsorption-desorption characteristics of a non-faradaic reaction by its shape and behavior at different scan rates. A reduction peak at -o.8 volts coupled with its oxidation peak exhibited the behavior for a faradaic electron-transfer reaction, and this peak was used in developing the method for pentachlorophenol. Controlled potential coulometry was used to electrolyze a bulk concentration of pentachlorophenol ix at -1.l volts versus Ag/AgCl in an attempt to obtain enough reduced material to identify the reduction products. This electrolyzed material was investigated with gas chromatography, infrared and UV spectrophotometry, and paper and thin-layer chromatography for this purpose. No reduction products of pentachlorophenol were found with any of these techniques. The surface of the mercury pool, which was used as the working electrode in the coulometric cell, may have been passivated during electrolysis, which prevented significant reduction of pentachlorophenol. The electrochemical procedure that was developed for pentachlorophenol analysis from my research offers some advantages of being fast and direct compared to the methods that are currently available for this purpose.
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Synthesis Gas Conversion with ZS M-5 Supported Ruthenium CatalystsEaton, Robin Elizabeth Young 01 January 1983 (has links)
Some bifunctional ZSM-5 supported ruthenium catalysts (Ru/ ZSM-5) were prepared by an extraction technique employing Ru 3(C0)12 • The weight percentage Ru ranged from approximately 1% to 8% Ru as determined by Atomic Absorption Spectroscopy. Characterization data employing Infrared (IR) Spectroscopy, X-ray Powder Diffractometry (XRPD), X-ray Photoelectron Spectroscopy (XPS/ESCA), Ion-Scattering Spectrometry (ISS) and Chemisorption were obtained for the catalysts. The data indicated the presence of highly dispersed Ruo2 particles of less than 60 A on the surface of the as-prepared (AP) catalysts. Calcination of the AP catalysts at 500°C for 24 h increased the particle size of the Ruo2 species. Characterization of the Ru/ZSM-5 Used catalyst with the highest Ru loading indicated the presence of Ru 0 and Ruo2 species suggesting that reduction of this AP catalyst was incomplete.
The AP catalysts were evaluated for their ability to convert synthesis gas to hydrocarbon products. A 1:1 H2:CO synthesis gas mixture was used in a continuous flow microreactor from 260°C to 320°C. Gas chromatography was employed for analysis of the gaseous effluent. The oil fraction (C5-C 11 hydrocarbons) was analyzed by Fluorescent Indicator Adsorption (FIA) Chromatography. At 300°C, the oil fraction obtained from the 0.98% Ru/ZSM-5 catalyst was composed of 71% aromatics, 4% olefins and 25% saturates . The catalytic data obtained for the 2.88% and 7.32% Ru/ZSM-5 catalysts are similar; it is concluded that there is no increase in the number of active metal sites for the conversion of synthesis gas due to layering of the Ru species in the 7.32% Ru/ZSM-5 catalyst. Furthermore, the two higher loadings of Ru did not cause the production of high yields of aromatics as obtained from the 0.98% Ru/ZSM-5 catalyst. This may be due to blockage of the acid sites in the ZSM-5 support which are known to catalyze the production of aromatics.
It was concluded that the AP catalysts contained highly dispersed small particles of Ru02 on the zeolite surface and agglomeration occurs when the catalysts are calcineff in air. Also, the AP catalysts were found to be active for the Fischer-Tropsch reaction. The oil produced by using these catalysts has a high aromatic content. Correlations between the catalyst structure and activity for the conversion of synthesis gas have been drawn.
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Effects of N-substituents on the Polymerization Properties of MaleimideAbayasekara, Dilip R. 01 January 1984 (has links)
The effect of the amide function and the carbethoxy function on the polymerization properties of maleimide are reported. The effects of these functions on homopolymerization and copolymerization (with styrene) were examined. These electron-withdrawing groups appeared to decrease the rate of homopolymerization and increase the rate of copolymerization.
N-carbamylmaleimide and N-carbethoxymaleimide were copolymerized with styrene in 1,4 -dioxane at 60.0° C at different feed ratios to high conversion. Copolymer composition, determined by elemental analysis and 1H NMR, indicated that while 1:1 copolymers were obtained with an equimolar feed ratio, the two systems were not alternating. It is of note that the copolymerizations were carried out at a very low total monomer concentration of 0.2 mol/L due to the limited solubility of N-carbamylmaleimide in the reaction solvent. If higher concentrations had been possible, 1:1 copolymer formation would have been enhanced.
Investigation of the complexation of maleic anhydride, maleimide, N-carbethoxymaleimide, N-carbamylmaleimide, N-phenylmaleimide and N-ethylmaleimide with the electron-donors styrene, furan, and 2-chloroethyl vinyl-ether was accomplished by use of ultraviolet (UV) spectroscopy and 1H NMR spectroscopy. It appeared generally that the electron-withdrawing groups increased the complexation of maleimide with the electron-donating comonomers. There was no evidence of complex formation with 2-chloroethyl vinyl ether for any of the compounds studied.
A continuous variation method using UV spectroscopy indicated that all observed charge-transfer complexes (maleic anhydride-styrene; N-carbethoxymaleimide-styrene; N-phenylmaleimide-styrene; maleic anhydride-furan; N-carbamylmaleimide-furan) had 1:1 stoichiometry. The formation constant of complexation between maleimide and styrene was increased towards the value of the complex formation constant for maleic anhydride-styrene when the electron-withdrawing groups -CONH2 and -C02Et were substituted on the maleimide N. The same effect was not observed for complexation with furan.
IR spectroscopy and 13c NMR spectroscopy indicate that the electron-withdrawing groups increase the double bond character of the maleimide carbonyl groups. The results of the complexation studies suggest that the carbonyl groups of maleimide may play a significant role in complex formation with styrene. The mechanism of complex formation with furan appears to be different from that of styrene.
It was also shown that when N-phenylmaleimide and maleic anhydride (both electron-accepting monomers) are copolymerized, a random copolymer results.
When reaction with styrene is considered, the results of this investigation indicate that electron-withdrawing N-substituents influence the polymerization properties of maleimide to be more like those of maleic anhydride.
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Interfacial Electrochemistry of Cytochrome c and MyoglobinBowden, Edmond F. 01 January 1982 (has links)
The interfacial electrochemistry of horse heart cytochrome c was studied at metal and metal oxide electrodes. Sperm whale myoglobin reactions at metal oxide and surface modified electrodes were also investigated. Emphasis was on the measurement and mechanistic interpretation of the heterogeneous electron transfer kinetic parameters for these electrode reactions.
The motivation for this study stems from the fact that some electron transfer proteins, e.g., cytochrome c, transfer electrons heterogeneously in physiological systems. Specific electrodes may, therefore, serve as suitable models for physiological surfaces. Electrode and membrane interfaces are both electrically charged and both have oriented hydration water layers.
The cyclic voltammetric behavior of cytochrome c at solid electrodes is strongly influenced by the purity of the sample. Following dissolution, commercial samples exhibit a continuous, time-dependent decrease in reversibility until a stable reproducible cyclic voltammogram is obtained after about one hour in quiet solution. The decrease in the formal heterogeneous electron transfer rate constant corresponding to this process is ≥ two orders of magnitude at doped tin oxide and indium oxide electrodes. However, commercial cytochrome c samples purified by ion-exchange chromatography exhibit more reversible responses which do not decay significantly with time.
Formal heterogeneous electron transfer rate constants ( k° ) for purified cytochrome c were determined in pH 7 tris/cacodylate media by analyzing cyclic voltammetric peak separations assuming that a = 0.5. Electrodes and approximate ranges of k° in cm/s: tin doped indium oxide, 10-3 to 10-2; fluorine doped tin oxide, 10-4 to 10-3; gold, 10-3; Pt, 10-3. Kinetics are also affected by electrode pretreatment, cytochrome c concentration, and electrolyte composition. Evidence for cytochrome c adsorption sites of differing affinities on indium oxide is presented. It is proposed that the exposed heme edge of cytochrome c is the electron transfer site and that the rate is controlled by a combination of electrostatic and chemical interfacial forces. A hydrophilic electrode surface along with a suitable surface charge appear to be sufficient conditions for facile electron transfer. Specific chemical and electrostatic interactions between cytochrome c lysine residues and charged oxygen groups on metal oxide surfaces are also likely. Electron tunneling to the exposed heme edge is proposed to be an important rate-controlling process for the metal oxide semiconductors.
Reductive and oxidative kinetics of commercial cytochrome c at tin oxide electrodes were measured using single potential step chronoabsorptometry ( SPS/CA ) and asymmetric double-potential step chronoabsorptometry, respectively. Formal rate constants were near lo-s cm/s for both reactions, but a and (1 - a) values were ca. 0.3 and < ca. 0.1, respectively. The irreversibility of these reactions appears to be due to surface adsorption of an impurity which restricts approach of the cytochrome c molecules to the electrode surface.
Reductive kinetics of myoglobin at tin oxide and at methyl viologen modified gold electrodes were measured using SPS/CA. The reaction was irreversible with marked adsorption effects. Electron transfer to diffusing molecules appeared to proceed through exposed heme groups of adsorbed denatured myoglobin molecules.
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The Synthesis of 4-Spiro-2-Aryloxazolines of Potential Pharmacological InterestCollins, Paul Waddell 01 January 1966 (has links)
Numerous and diverse physiological actions are found among 2-oxazoline compounds. No reports of the synthesis or biological testing of 4-spiro-2-aryl-2-oxazolines were found in the literature. On the basis of the known pharmacological activities of certain aza- and diazaspirans, it was felt that 4-spiro-2-aryl-2-oxazolines should possess medicinal activity. In particular, it was reasoned that the combination in a bicyclic spiro structure of the 2-oxazoline ring with rings systems commonly found in synthetic antitussive compounds might result in active antitussive agents.
The aim of this research was the synthesis of a series· of 2-aryl-2-oxazoline-4-spirocyclopentanes and a series of 1'-methyl-2-aryl-2-oxazoline-4-spiro-4’-piperidines. Six members were to be prepared in each series in which the aryl group represents respectively, a phenyl, a p-chloro, p-methyl, p-nitro, p-ethoxy, and p-dimethylaminophenyl radical.
With the exception of the p-dimethylamino derivative, acylation of 1-aminocyclopentane-1-carboxylic acid gave the corresponding amido acids, the methyl esters of which were reduced with lithium borohydride to the corresponding amide-alcohols. Dicyclohexylcarbodiimide was employed to produce 1-(p-dimethylaminohenzamido)-1-carbomethoxycyclopentane from p-dimethylaminobenzoic acid and 1-amino-1-carbomethoxycyclopentane after unsuccessful attempts to prepare it by the mixed carbonic anhydride method. Each amide-alcohol, on treatment with hydrogen chloride in chloroform, rearranged by N to 0 acyl migratilon to the corresponding 1-amino-1-cyclopentylmethyl p-substituted benzoate hydrochloride. On treatment with base these compounds rearranged to the original amide-alcohols by 0 to N acyl migration. This sequence of reactions confirmed the structure of the amide-alcohols.
Treatment of each amide-alcohol with thionyl chloride afforded the corresponding, 2-aryl-2-oxazoline-4-spirocyclopentanes in good yields. The structure of these compounds was confirmed in each case by the infrared spectra and elemental analyses of the oxazoline and/or its hydrochloride. Futhermore, the structure of 2-(p-ethoxyphenyl) -2-oxazoline-4-spirocyclopentane was confirmed by a proton magnetic resonance spectrum.
Each oxazoline compound ( except the p-dimethylamlnoderivative) was converted to the corresponding 1-(p-substitutedbenzamido)-1-chloromethylcyclopentane by treatment with a saturated solution of hydrogen chloride in dioxane. Each chloroamide compound ( except the p-nitro derivative) was converted to the corresponding oxazoline by treatment with alkali in order to provide further evidence for the oxazoline structure of the products isolated from the thionyl chloride reactions.
4-Amino-l-mothylpiporidine-4-carboxylic acid was obtained by both acid and alkaline hydrolysis of the corresponding hydantoin. 4-Amino-4-hydroxymethyl-l-methylpiperidine, which was obtained by the reduction of 4-amino-4-carbomethoxy-l-methylpiperidine with lithium borohydride, was treated with benzoyl chloride and p-methylbenzoyl chloride to give respectively, 4-benzamido- 4-hydroxymethyl-l-methylpiperidine and 4-(p-methylbenzamido)- 4-hydroxymethyl-l-methylpiperidine. 4-Benzamido- 4-hydroxymethyl-l-methylpiperidine was also obtained by the reduction with lithium borohydride of 4-benzamido- 4-carbomethoxy-1-methylpiperidine which was prepared by benzoylation of 4-amino-4-carbomethoxy-l-methylpiperidine. 1'-Methyl-2-phenyl- and 1’-methyl-2-(p-methylphenyl)-2-oxazoline-4-spiro-4'-piperidine were prepared by treatment of the corresponding amido-alcohols with thionyl chloride.
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Electrochemical Determination of the Heterogeneous Electron Transfer Kinetics of Soluble Spinach FerredoxinCrawley, Charlene D. 01 January 1982 (has links)
The application of electrochemical techniques to biological systems has become an attractive method for characterizing the redox and electron transfer behavior of biomacromolecules. This study focuses on the role of soluble spinach ferredoxin (Fd) in photosynthesis where it functions as an electron carrier to membrane bound species in the plant chloroplast. An electrochemical model is used where in Fd now serves as a soluble redox species which undergoes oxidation and reduction via electron transfer at an electrode. This type of model is significant in that both the membrane and electrode reactive sites are characterized by charged bilayer interfacial regions which significantly influence electron transfer rates.
The formal heterogeneous electron transfer rate constant, kf0:h' and the eletrochemical transfer coefficient, a, were determined using transient and steady state electrochemical techniques. Transient oxidative and reductive kinetic data were obtained spectroelectrochemically via single potential step chronoabsorptometry (SPSC) at three different surfaces: methyl viologen modified gold (MVMG) minigrid electrodes, tin oxide (Sn02) semiconductor electrodes and at metallized plastic gold optically transparent electrodes (MPOTE). The steady state measurements were made via hydrodynamic voltammetry at a MVMG rotating ring - disk electrode (RRDE).
Only the modified gold surfaces resulted in behavior suitable for the determination of heterogeneous electron transfer kinetic parameters. The transient kinetics of Fd were initially evaluated using an irreversible Butler-Volmer kinetic model descriptive of species exhibiting slow rates of electron transfer at an electrode surface. This yielded an average kf0;h = 6.5 (± 1.3) x 10- 5cm/sec and a = 0.60 (±0.16) for reductive experiments performed at four
different modified gold surfaces . Recently the theory for SPSC was extended to quasi-reversible systems, which undergo moderate rates of electron transfer. Since Fd exhibits quasi-reversible behavior at the MVMG grid, the transient reductive data were reanalyzed using this more exact model. The values obtained using the quasi-reversible model were kf,0’h= 1.16 (±0.5) x 10-4 cm/sec and α = 0.42 ( ±0.06 ). The corresponding reductive steady state results at the
modified RRDE yielded kf,0’h = 5.9 ( ±0.05 ) x 10-4 cm/sec and α=0.476 (± 0.001). Oxidative experiments were only successful with transient experiments at the MVMG minigrid surface where in kf,0’h =3.39 (± 0.01) x 1 0- 5 cm/sec and α = 1.17 (0.02). Absorbance data also indicates protein adsorption as a prestep to electron transfer. This type of phenomenon is common to biological molecules reacting at electrodes. The behavior of Fd at these surfaces and the kinetic results are discussed in terms of mechanistic implications.The formal heterogeneous electron transfer rate constant, kf0h and the eletrochemical transfer coefficient, a, were determined using transient and steady state electrochemical techniques. Transient oxidative and reductive kinetic data were obtained spectroelectrochemically via single potential step chronoabsorptometry (SPSC) at three different surfaces: methyl viologen modified gold (MVMG) minigrid electrodes, tin oxide (Sn02) semiconductor electrodes and at metallized plastic gold optically transparent electrodes (MPOTE). The steady state measurements were made via hydrodynamic voltammetry at a MVMG rotating ring - disk electrode (RRDE).
Only the modified gold surfaces resulted in behavior suitable for the determination of heterogeneous electron transfer kinetic parameters. The transient kinetics of Fd were initially evaluated using an irreversible Butler-Volmer kinetic model descriptive of species exhibiting slow rates of electron transfer at an electrode surface. This yielded an average kf0h = 6.5 (± 1.3) x 10- 5cm/sec and a = 0 . 60 (±0.16) for reductive experiments performed at four
different modified gold surfaces . Recently the theory for SPSC was extended to quasi-reversible systems, which undergo moderate rates of electron transfer. Since Fd exhibits quasi-reversible behavior at the MVMG grid, the transient reductive data were reanalyzed using this more exact model. The values obtained using the quasi-reversible model were kf0h= 1.16 (±0 . 5) x 10-4 cm/sec and α = 0.42 ( ±0.06 ). The corresponding reductive steady state results at the
modified RRDE yielded kf0h = 5.9 ( ±0.05 ) x 10-4 cm/sec and α=0.476 (± 0.001). Oxidative experiments were only successful with transient experiments at the MVMG minigrid surface where in kf0h =3.39 (± 0.01) x 1 0- 5 cm/sec and α = 1.17 (0.02). Absorbance data also indicates protein adsorption as a prestep to electron transfer. This type of phenomenon is common to biological molecules reacting at electrodes. The behavior of Fd at these surfaces and the kinetic results are discussed in terms of mechanistic implications.
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The Synthesis and Characterization of Some Thermally Stable Polypyrazoles and Acetylene Terminated AspartimidesConnell, John W. 01 January 1986 (has links)
Reactions involving the nucleophilic addition cyclization to activated acetylenes have been employed as a novel route to moderate to high molecular weight polymers. Polypyrazoles (PI to P12) have been prepared from the Michael-type addition cyclization of various aromatic dihydrazines to aromatic dipropynones in m-cresol. The aromatic dihydrazines employed were 4, 4'-dihydrazinodiphenyl ether (4,4' -DHDPE), 4,4 '-dihydrazinodiphenylmethane (4, 4'-DHDPM), and 4, 4' -dihydrazinodiphenyl sulfone (4,4'-DHDPS). The dipropynone sutilized were 1,1’- (1,4-phenylene) bis (3-phenyl- 2-propyn-l-one), (l,4 -PPPO), 1,1’ - (1, 3-phenylene) bis (3 -phenyl- 2 -propyn-l-one), (1,3-PPPO), 1,1 '-(1,4 -phenylene) bis (2 -propyn- l-one), (1,4 -PPO), and 1,1’- (1,3 -phenylene) bis (2 -propyn-l-one), (1,3-PPO).
Polymers (PI -P6) obtained from the phenyl substituted dipropynones (1,3 and 1,4 -PPPO's) had inherent viscosities ranging from 0.15 to 0.33 dL/g. The glass transition temperatures (Tg) ranged from 225 to 261°C as measured by differential scanning calorimetry (DSC). The temperatures of 10% weight loss as measured by thermogravimetric analysis (TGA) ranged from 400 to 500°C in air and 470 to 512°C in nitrogen. In a few cases creasable films were obtained by solution casting from chloroform.
Polymers (P7-PI2) obtained from the unsubstituted dipropynones (1,3 and 1,4 -PPOs) had inherent viscosities ranging from 0.31 to 1.05 dL/ g. The Tg's ranged from 202 to 266°C as measured by DSC. The temperatures of -10% weight loss as measured by TGA ranged from 415 to 483°C in air and 466 to 512° C in nitrogen. In a few cases creasable films were obtained by solution casting from N, N-dimethylacetamide.
Moderate to high molecular weight polypyrazoles were readily prepared by the reaction of aromatic dipropynones with aromatic dihydrazines. In a few cases creasable films were obtained. The Tg's ranged from 202 to 261°C as measured by DSC. The polymers exhibited good thermal stability as measured by TGA.
Reactions involving the nucleophilic addition to activated alkenes have been employed as a route to novel acetylene terminated aspartimides (ATA's). Novel ATA's were prepared by the Michael -type addition of a series of aromatic diamines to two moles of N-(3-ethynylphenyl) maleimide (NEM). NEM was prepared by the condensation reaction of 3-ethynylaniline and maleic anhydride. The aromatic amines utilized were aniline,4,4-diaminodiphenyl methane, 4, 4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 4,4'-bis (3-aminophenoxy) benzophenone, 4,4' -bis (4-aminophenoxyphenyl) sulfone, and 1,1, 3-trimethyl-3, S-bis(4 -aminophenoxy) indane.
The ATA's were characterized by infrared spectroscopy (IR) and 1H nuclear magnetic resonance spectroscopy (NMR). The ATAs were isolated as a mixture of stereoisomers since a chiral carbon is created during addition. No attempt was made to separate the stereoisomers. Using a DSC the heats of reaction (ΔH) of the acetylene groups was measured, the ΔH's ranged from -23.2 to -49.2 kcal /mole presumably depending upon acetylene density (concentration).
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Reactions of Substituted Pyridinium Salts with Cyanide; Formation and Metal Complexes of 2,2'bis (hydroxymethyl)-4,-4'bipyridineEseonu, Dorothy N. 01 January 1989 (has links)
The unique combination of properties of bipyridinium salts and their use in biological systems, chemical reactions, and as herbicides in agriculture have made them a discovery of major international importance. The controversy about the position of attack of the cyanide ion on the pyridine ring and the discovery of the formation of unsubstituted bipyridinium salts from the reaction of pyridinium salt with cyanide ion opened a new area of research. The current work involved a study of reactions of substituted pyridinium salts with cyanide ion. The substituted pyridinium salts were prepared by the literature methods. The 2- and 3- cyanopyridinium salts reacted with cyanide ion to form 4-cyano-1, 4-dihydropyridines. The 3, 4-dicyano-1, 4-dihydropyridines were very stable; therefore, they were isolated and characterized. An unusual product, 1-methyl-2-oxo-1, 2-dihydro-4-pyridine carbonitrile, was isolated from the reaction of 1-methyl-2-cyanopyridinium iodide with cyanide ion.
The reaction of 1-benzyl-2-(acylamino) pyridinium bromide with cyanide ion did not form a 1, 4-dihydropyridine; rather, hydrogen bromide was lost when the reaction mixture was heated to a boil and 1-benzylpyridinium-2-acylimide was formed. The reaction of the 1-benzyl-2-acetylpyridinium salt, the 1-benzyl-2-bromopyridinium salt, and the 1-benzyl-2-ethylpyridinium salt with cyanide ion formed complicated products that were not characterized.
The reactions of 1-benzyl-2-methylpyridinium bromide, 1-benzyl-2-(hydroxymethyl) pyridinium bromide and 1-benzyl-2, 6-dimethylpyridinium bromide with cyanide ion in water, acetone, acetone-water or 95% ethanol solutions formed dark blue or green solutions. Electron spin resonance spectroscopy showed the presence of a radical in the dark-blue or green solutions. A dark solid formed from the solutions. Oxidation of the solid with an acetone and ethanolic iodine solution or acidic ethanol solution resulted in the formation of the corresponding new, 1, 1'-dibenzyl-2, 2'-bis(hydroxymethyl)-4-4'-bipyridinium dibromide 75, and the known 1, 1'-dibenzyl-2, 2'-dimethyl-4, 4'-bipyridinium dibromide, and 1, 1'-dibenzyl-2, 2', 6, 6'-tetramethyl-4, 4'-bipyridinium dibromide dimers.
The new dimer 75 was reduced in aqueous solution at potential (E°) of about -0.34V vs NHE. It was also debenzylated with triphenylphosphine in refluxing DMF to give 2, 2'-bis(hydroxymethyl)-4, 4'-bipyridine 89. 1, 1'-Dibenzyl-2, 2'-dimethyl-4, 4'-bipyridinium dibromide was also debenzylated to give 2, 2'-dimethyl-4, 4' bipyridine, which was acidified with hydrogen chloride gas, and the salt 2', 2'-dimethyl-4, 4'-bipyridyl dihydrochloride was formed. These were the first report on debenzylation of bipyridinium dimers. The reaction of 89 with cobalt thiocyanate formed a new 2, 2'-bis(hydroxymethyl)-4, 4'-bipyridine cobalt thiocyanate octahedral complex. The reaction of 2-(hydroxymethyl)pyridine and 2-(2-hydroxyethyl) pyridine with cobalt thiocyanate gave the corresponding octahedral complexes.
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A collection of 47 published papersSteele, Derek January 1969 (has links)
No description available.
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