Solvent Effects in the Partition of Phenols as Ion-Pairs with Tetrabutyl Ammonium Cations

1976 ◽  
Vol 59 (5) ◽  
pp. 1175-1179 ◽  
Author(s):  
Thomas D Doyle ◽  
Joseph B Proctor
Keyword(s):  
Ion Pairs ◽  
Quantitative Agreement ◽  
Ortho Position ◽  
Exponential Relationship ◽  
Pronounced Increase ◽  
Polar Groups ◽  
Tetrabutyl Ammonium ◽  
Extraction Constants ◽  
Anionic Charge ◽  
Controversial Concept

Abstract The extraction of phenols as ion-pairs with tetrabutyl ammonium cations was studied with respect to variation of distribution as a function of solvent composition. The large solvent effect observed for 12 phenols gave quantitative agreement with an exponential relationship previously developed for other classes of ion-pairs and had approximately the same magnitude. An exception was noted for phenols substituted at the ortho position by nonpolar groups; decrease of the exponential value in these cases provided support for the controversial concept of specific solvation. Ortho substitution by polar groups led to a pronounced increase of extraction constants; this was explained in terms of delocalization of the anionic charge. Formylation via the Reimer-Tiemann reaction was observed as a complication in the extraction of some of the phenols.

The impacts of heavy metals on oxidative stress and growth of spring barley

2012 ◽  
Vol 7 (2) ◽  
pp. 299-306 ◽  
Author(s):  
Romualdas Juknys ◽  
Giedrė Vitkauskaitė ◽  
Milda Račaitė ◽  
Jonė Venclovienė
Keyword(s):  
Oxidative Stress ◽  
Heavy Metals ◽  
Lipid Peroxidation ◽  
Growth Inhibition ◽  
Spring Barley ◽  
Hordeum Vulgare L ◽  
Exponential Relationship ◽  
Pronounced Increase ◽  
Lead And Cadmium ◽  
Wide Range

AbstractOxidative stress is accepted to play a significant role in stress symptoms, caused by different stressors in a variety of organisms. In this study seedlings of spring barley (Hordeum vulgare L.) were exposed to a wide range of copper, zinc, chromium, nickel, lead and cadmium concentrations in order to determine the relationships between heavy metals-induced oxidative stress and plant growth inhibition. All investigated heavy metals induced an essential increase in lipid peroxidation and a reduction of dry biomass along with an increase in metal concentration in the nutrient solution. A very close and statistically significant exponential relationship between lipid peroxidation and growth inhibition was detected in this study. According to the results of analysis of variance (ANOVA), the intensity of nonspecific oxidative stress is identified as the main factor of barley growth inhibition, explaining 75% of total variance. Almost 10% of growth inhibition is attributed to the specific impact of heavy metals. The most pronounced increase of malondialdehyde content and growth inhibition was observed in Cu and Cd treatments, whereas the lowest changes in observed indicators were detected after exposure to Zn and Pb.

Computer-aided method for studying the extraction behaviour and determining the extraction constants of ion pairs

1991 ◽  
Vol 248 (2) ◽  
pp. 473-481 ◽  
Author(s):  
J.J. Halvax ◽  
J.M. Reijn ◽  
G. Wiese ◽  
W.P. van Bennekom ◽  
A. Bult
Keyword(s):  
Ion Pairs ◽  
Extraction Behaviour ◽  
Extraction Constants ◽  
Computer Aided

Extraction and Partition Chromatography of Tolbutamide as Ion-Pairs with Quaternary Ammonium Cations

1976 ◽  
Vol 59 (5) ◽  
pp. 1170-1174
Author(s):  
Thomas D Doyle ◽  
Susan Barkan
Keyword(s):  
Free Acid ◽  
Ion Pairs ◽  
Ammonium Hydroxide ◽  
Ammonium Ion ◽  
Quantitative Calculation ◽  
Treatment Standard ◽  
Extraction Constants ◽  
Immobile Phase ◽  
Chromatographic Procedure

Abstract The partition of tolbutamide (1-butyl-3-(p-tolylsulfonyl) urea) as ion-pairs with homologous tetraalkyl ammonium cations was studied. The determination of experimental extraction constants permitted quantitative calculation of distribution ratios, in agreement with theoretical relationships, over a continuous range of about one billion. The nature and the concentration of the counter-ion and solvent composition were the variables studied. Based on the theoretical results, a rapid partition chromatographic procedure was devised. A solution of tolbutamide sample in 10% aqueous tetraethyl ammonium hydroxide is incorporated in the system as the immobile phase in the partition column. A 1 + 1 mixture of chloroform and isooctane removes extraneous materials; then chloroform elutes the tolbutamide-tetraethyl ammonium ion-pair, which is converted to the free acid by passing the eluate through a phosphoric acid segment, and tolbutamide is determined spectrophotometrically without further treatment. Standard recoveries averaged 100.5 ± 0.70%; commercial tablets assayed 100.5 ± 0.85%.

scholarly journals The electrical conductivity caused by insoluble monomolecular films of fatty acid on water

1929 ◽  
Vol 125 (798) ◽  
pp. 394-401 ◽  
Keyword(s):  
Colloidal Particle ◽  
Opposite Sign ◽  
Ion Pairs ◽  
Hydrogen Ions ◽  
Monomolecular Layer ◽  
Monomolecular Film ◽  
Polar Groups ◽  
Monomolecular Films ◽  
Free Hydrogen ◽  
Lines Of Evidence

The well-known researches on thin films of insoluble fatty substances on water have brilliantly demonstrated that such films are monomolecular and that the molecules are oriented with their polar groups in contact with the water. Thus stearic acid spreads on water with its carboxyl groups on the water surface. No one, however, has as yet investigated the possible dissociation of such fatty acids with formation of free hydrogen ions in the water, leaving the fatty ions behind in a monomolecular film on the surface. Such dissociation need not and probably should not involve more than a small fraction of the molecules on the surface. One of us has pointed out the enormous voltages which would be caused between a complete monomolecular layer of fresh ions and the charges of opposite sign, vastly exceeding the electromotive forces of vigorous chemical reactions. This and many other lines of evidence have led to the theory of sparse surface dissociation," according to which a surface such as that of a colloidal particle may be largely covered or consist of undissociated molecules or accorded ion pairs, forming a double layer in the strict Helmholtz sense, but with a further portion of the surface covered only with unbalanced or singly adsorbed ions whose partner remain free and mobile somewhere in the solution.

Computer-aided method for studying the extraction behaviour and determining the extraction constants of ion pairs

1991 ◽  
Vol 248 (2) ◽  
pp. 483-492 ◽  
Author(s):  
J.J. Halvax ◽  
J.M. Reijn ◽  
G. Wiese ◽  
W.P. van Bennekom ◽  
A. Bult
Keyword(s):  
Ion Pairs ◽  
Extraction Behaviour ◽  
Extraction Constants ◽  
Computer Aided

Specific Solvation of Ion-Pairs: Examination of Anion-Solvent Complexes by Spectral Methods

1977 ◽  
Vol 60 (1) ◽  
pp. 52-55
Author(s):  
Richard M Venable ◽  
Thomas D Doyle
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Methylene Chloride ◽  
Ion Pairs ◽  
Ion Pair ◽  
Resonance Spectroscopy ◽  
Specific Solvation ◽  
Dextromethorphan Hydrobromide ◽  
Controversial Concept

Abstract The results of experiments performed using infrared (IR) and nuclear magnetic resonance spectroscopy support the theory that chloroform associates by hydrogen bonding to the halide ion of ion-pairs. IR spectra of dextromethorphan hydrobromide in chloroform showed the same effect. This provides a definitive, albeit qualitative, demonstration of the controversial concept of specific solvation of ion-pairs, central to an understanding of solvent effects in analysis of drugs by ion-pair partition. Quantitative implications are less clear. Indications that several molecules of chloroform may be involved in complexation are presented and discussed. Results of similar experiments with methylene chloride are inconclusive.

Quantitative Diameter Measurements of Chromatin and TMV Fibers in the Freeze-Dried State

1988 ◽  
Vol 46 ◽  
pp. 170-171
Author(s):  
B. D. Athey ◽  
A. L. Stout ◽  
M. F. Smith ◽  
J. P. Langmore
Keyword(s):  
Reliable Method ◽  
Fiber Diameter ◽  
Quantitative Agreement ◽  
One Dimension ◽  
Fiber Axis ◽  
Two Dimensional ◽  
Fiber Density ◽  
Variable Diameter ◽  
Freeze Dried ◽  
Expected Values

Although there is general agreement that Inactive chromosome fibers consist of helically packed nucleosomes, the pattern of packing is still undetermined. Only one of the proposed models, the crossed-linker model, predicts a variable diameter dependent on the length of DNA between nucleosomes. Measurements of the fiber diameter of negatively-stained and frozen- hydrated- chromatin from Thyone sperm (87bp linker) and Necturus erythrocytes (48bp linker) have been previously reported from this laboratory. We now introduce a more reliable method of measuring the diameters of electron images of fibrous objects. The procedure uses a modified version of the computer program TOTAL, which takes a two-dimensional projection of the fiber density (represented by the micrograph itself) and projects it down the fiber axis onto one dimension. We illustrate this method using high contrast, in-focus STEM images of TMV and chromatin from Thyone and Necturus. The measured diameters are in quantitative agreement with the expected values for the crossed-linker model for chromatin structure

A Comparison of the Ultrastructural Morphology of Hepatic Necrosis in BDF1 Mice

1981 ◽  
Vol 39 ◽  
pp. 586-587
Author(s):  
Becky Jackson
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Preliminary Investigation ◽  
Hepatic Necrosis ◽  
Hepatic Tissue ◽  
Pronounced Increase ◽  
Glycogen Store ◽  
Ultrastructural Morphology ◽  
Mitochondrial Integrity ◽  
Glycogen Stores

Preliminary investigation has indicated similarity in hepatic ultrastructural morphology in nutritional deprivation, and cyanide induced hepatic necrosis. Analysis of hepatic tissue has indicated disruption of intracellular membranes, specifically, reduction in rough endoplasmic reticulum (RER) mitochondrial integrity, and glycogen stores. An increase in smooth endoplasmic reticulum (SER) portion was observed.To further investigate the apparent equivalence of necrotic morphology, ultrastructura1ly, BDF1 mice were subjected to senescence, nutritional deprevation, potassium cyanide (KCN) induced toxemia, and acetaminophen induced toxemia. Controls were utilized to ellucidate non-necrotic hepatocellular normals. U1trastructura1 investigation of controls (Fig. 1) shows densely granular RER, abundant glycogen stores, and morphologically normal mitochondria. Subjects with acetaminophen induced necrosis exhibit reduced normal RER with increased levels of dialated, vesicular RER in apparent conversion to SER (Fig. 2), loss of mitochondrial integrity, and glycogen store reduction. Senescent subjects exhibit a pronounced increase in SER and loss of glycogen store. (Fig. 3). Investigation of the senescent SER at high magnification (Fig. 5) indicates that the SER is arising from degranulating and vesiculating RER.

Microscopic versus process parameters in heavy-oil upgrading

1992 ◽  
Vol 50 (1) ◽  
pp. 366-367
Author(s):  
V.A. Munoz ◽  
R.J. Mikula ◽  
C. Payette ◽  
W.W. Lam
Keyword(s):  
Molecular Weight ◽  
Liquid Fuels ◽  
Chemical Components ◽  
Heavy Oils ◽  
Synthetic Fuels ◽  
High Hydrogen ◽  
Optical Texture ◽  
Polar Groups ◽  
Anisotropic Character ◽  
Planar Molecules

The transformation of high molecular weight components present in heavy oils into useable liquid fuels requires their decomposition by means of a variety of processes. The low molecular weight species produced recombine under controlled conditions to generate synthetic fuels. However, an important fraction undergo further recombination into higher molecular weight components, leading to the formation of coke. The optical texture of the coke can be related to its originating components. Those with high sulfur and oxygen content tend to produce cokes with small optical texture or fine mosaic, whereas compounds with relatively high hydrogen content are likely to produce large optical texture or domains. In addition, the structure of the parent chemical components, planar or nonplanar, determines the isotropic or anisotropic character of the coke. Planar molecules have a tendency to align in an approximately parallel arrangement to initiate the formation of the nematic mesophase leading to the formation of anisotropic coke. Nonplanar highly alkylated compounds and/or those rich in polar groups form isotropic coke. The aliphatic branches produce steric hindrance to alignment, whereas the polar groups participate in cross-linking reactions.

Chemistry of gaseous ion pairs produced by thermal collisions

1980 ◽  
Vol 77 ◽  
pp. 759-768 ◽  
Author(s):  
R. Stephen Berry
Keyword(s):  
Ion Pairs
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