A simplified preparation of fully deuterated, high molecular weight hydrocarbons

1967 ◽  
Vol 45 (13) ◽  
pp. 1511-1518 ◽  
Author(s):  
J. G. Atkinson ◽  
M. O. Luke ◽  
R. S. Stuart
Keyword(s):  
Molecular Weight ◽  
Fixed Bed ◽  
Structural Isomerization ◽  
Chemical Purity ◽  
Individual Preparation ◽  
The Individual ◽  
Deuterium Gas ◽  
Asymmetric Carbon ◽  
Material Exchange ◽  
Deuterated Hydrocarbons

A novel system for the individual preparation of fully deuterated hydrocarbons with 10 to 36 carbon atoms is described. The system permits the use of unsaturated and saturated, cyclic and acyclic starting materials and results in the perdeuterated, saturated equivalent of the starting material. Exchange occurs between hydrocarbon liquid and deuterium gas over carbon-supported, fixed-bed catalysts of Rh, Pt, and Pd at 190–200 °C and results in perdeuterated products of high isotopic and chemical purity. No cracking or structural isomerization occurs under the conditions used, but epimerization of asymmetric carbon atoms does occur. Yields of 35–75% are obtained, the chief losses being due to volatilization and sample withdrawal. The deuterated hydrocarbons prepared by liquid-phase exchange include n-decane-d22, n-dodecane-d26, n-hexadecane-d34, n-octadecane-d38, n-tetracosane-d50, n-octacosane-d58, n-hexatriacontane-d74, pristane-d40, squalane-d62, cyclododecane-d24, 1,2-dicyclohexylethane-d26, and decalin-d18.

Separation and Characterization of Standard Propoxyphene Diastereomers and Their Determination in Pharmaceutical and Illicit Preparations

1981 ◽  
Vol 64 (4) ◽  
pp. 875-883
Author(s):  
Shiv K Soni ◽  
Daniel Van Gelder
Keyword(s):  
High Pressure ◽  
Optical Isomers ◽  
Gold Chloride ◽  
Melting Points ◽  
Eutectic Melting ◽  
Racemic Mixtures ◽  
The Individual ◽  
Isomeric Mixtures ◽  
Asymmetric Carbon

Abstract Due to the existence of 2 asymmetric carbon atoms in: the propoxyphene molecule, there are 4 diastereomers: alpha dextro, alpha levo, beta dextro, and beta levo. Only α-d-propoxyphene is included under the federal Controlled Substances Act. Baseline separations of propoxyphene from various incipients (aspirin, caffeine, phenacetin, and acetaminophen) present in pharmaceutical and illicit preparations, and between the alpha and beta diastereomers, were achieved by high pressure liquid chromatography. The column eluant was collected and propoxyphene was extracted. The optical isomers were differentiated and characterized by melting points and by chemical microcrystalline tests. Using hot stage thermomicroscopy, the eutectic melting points of binary isomeric mixtures of propoxyphene bases and salts were found to be depressed about 10° and 15-30°C, respectively, below the individual isomer melting points. The characteristic microcrystals formed with the alpha racemic mixtures by using a glycerin-aqueous gold chloride reagent were not produced by the beta racemic mixtures.

Molecular weight determines the frequency of delayed type hypersensitivity reactions to heparin and synthetic oligosaccharides

2005 ◽  
Vol 94 (12) ◽  
pp. 1265-1269 ◽  
Author(s):  
Susanne Alban ◽  
Roland Kaufmann ◽  
Edelgard Lindhoff-Last ◽  
Wolf-Henning Boehncke ◽  
Ralf J. Ludwig ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Heparin Therapy ◽  
Delayed Type Hypersensitivity ◽  
Published Data ◽  
Low Molecular Weight ◽  
Hypersensitivity Reactions ◽  
Type Iv ◽  
Total Data ◽  
The Individual

SummaryEczematous lesions, resulting from type IV sensitizations are well-known and relatively frequent cutaneous adverse effects of s.c. heparin therapy. If anticoagulation is further required intravenous heparin, heparinoids or lepirudin may be used as a substitute. However, these alternatives are not optimal in terms of practicability and/or safety-profiles. As molecular weight of different heparin preparations has repetitively been implied to determine the frequency of sensitization, we hypothesized, that due to its low molecular weight the pentasaccharide fondaparinux may provide a practicable and safe anticoagulant therapy in patients with delayed type hypersensitivity reactions (DTH) to heparin and other oligosaccharides. To test this concept, patients referred for diagnosis of cutaneous reactions after s.c. anticoagulant treatment underwent a series of in vivo skin allergyand challenge-tests with unfractionated heparin, a series of low molecular weight heparins (nadroparin, dalteparin, tinzaparin, enoxaparin and certoparin), the heparinoid danaparoid and the synthetic pentasaccharide fondaparinux. In total, data from twelve patients was evaluated. In accordance with previously published data, we report a high crossreactivity among heparins and heparinoids. In contrast – and in support of our initial hypothesis – sensitization towards the synthetic pentasaccharide fondaparinux was rarely observed. Plotting the cumulative incidence against the determined molecular weight of the individual anticoagulant preparations, shows that molecular weight generally is a key determinant of sensitization towards heparins and other oligosaccharides (r2=0.842, p=0.009). Hence, fondaparinux may be used as a therapeutic alternative in patients with cutaneous DTH relations towards heparin and other polysaccharides.

scholarly journals Sorption of Heavy Metal Ions of Chromium, Manganese, Selenium, Nickel, Cobalt, Iron from Aqueous Acidic Solutions in Batch and Dynamic Conditions on Natural and Synthetic Aluminosilicate Sorbents

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5271
Author(s):  
Jolanta Flieger ◽  
Justyna Kawka ◽  
Wojciech Płaziński ◽  
Rafał Panek ◽  
Jarosław Madej
Keyword(s):  
Metal Ions ◽  
Fixed Bed ◽  
Sorption Properties ◽  
Column Studies ◽  
Acidic Solutions ◽  
Nickel Cobalt ◽  
X Zeolite ◽  
Synthetic Zeolites ◽  
The Individual ◽  
Natural And Synthetic

Zeolites are materials with known sorption properties. The sorption is thought to progress mainly by ion exchange with Na+, K+, Mg2+, Ca2+ or H+ from the zeolite exchange sites. The aim of the study was to compare the sorption properties of natural and synthetic zeolites on the example of the removal of selected metals from aqueous acidic solutions. Uptake experiments for selected ions of chromium, manganese, selenium, nickel, cobalt, and iron were performed using the batch and kinetic column methods. The sorption of the individual metal ions in mg per 1g of sorbent was determined for each sorbent. The relative affinity sequence of the examined cations toward the various sorbent was presented. The Langmuir model was used to model the adsorption equilibrium. Vermiculite under 1 mm of diameter (SF), Na-X, and Na-A were proved to be the most suitable for the individual uptake of studied metal ions. It was observed that the behavior of selenium ions differed from the remaining ones which was interpreted that selenium undergoes adsorption in the anionic form. The fixed-bed column studies were performed using Na-A, ensuring the sorption of selenium in the presence of iron(III) ions. The experiments were conducted using Na-X zeolite pre-loaded by Fe(III) as well as unmodified sorbent eluted by an equimolar mixture containing 100 ppm of Fe and Se. Obtained results prove that selenium sorption improves if other metal ions such as iron appear in the acidic solution. That efficient selenium sorption conditions can be applied to remove selenium which was recognized as toxic at higher levels.

Evaluation of Milkoscan 104 Infrared Milk Analyzer

1980 ◽  
Vol 63 (5) ◽  
pp. 973-980
Author(s):  
F R Van De Voort
Keyword(s):  
Molecular Weight ◽  
Regression Analysis ◽  
Standard Deviation ◽  
Linear Regression Analysis ◽  
Average Molecular Weight ◽  
Important Variable ◽  
Standard Errors ◽  
Milk Component ◽  
Mean Differences ◽  
The Individual

Abstract The Milkoscan 104, a single cell, dual wavelength infrared milk analyzer, was assessed to see if it would meet the newly set AOAC specifications for accuracy and reproducibility required for official sanctioning of the instrument for milk component analysis. This assessment was carried out using herd, individual cow, commercial, and composite random milks, and produced mean differences and standard deviations of difference of <0.02% and ±0.02% for reproducibility and <0.05% and ±0.06% for accuracy. Results outside these values were encountered in the individual cow milks, for which the instrument was not specifically calibrated. The average molecular weight of the milkfat was an important variable because 2 anomalous milks were present in the calibration milks, thus restricting the overall accuracy obtainable. Linear regression analysis of chemical vs instrumental results showed good linearity and provided standard errors of the estimate of the same magnitude as the standard deviation of the differences. A separate assessment of the instrument for within- and between-day variation showed no practical significant differences. Based on the overall results, the Milkoscan 104 was judged to be capable of meeting the AOAC specifications set for fat, protein, and lactose analysis.

scholarly journals Safe drinking water: effect of granular activated carbon bed characteristics on iron removal from water

2016 ◽  
Vol 18 (1) ◽  
pp. 1
Author(s):  
Md Golam Rasul ◽  
Imtiaz Ahmed ◽  
Md Iqbal Hossain
Keyword(s):  
Drinking Water ◽  
Activated Carbon ◽  
Chemical Engineering ◽  
Fixed Bed ◽  
Granular Activated Carbon ◽  
Water Effect ◽  
Engineering Research ◽  
Household Water ◽  
The Individual ◽  
Water Filters

<p>Tuning the characteristics of granular activated carbon bed (GAC-bed) in household water-filters would be a technique to maintain iron at the required-level in drinking water. In the present study the individual effects of the depth of GAC-bed and the size and porosity of GAC particles on the iron removing capacity are investigated experimentally. A spectrophotometer is used to measure iron-content in water. It is observed that iron removing capacity increases monotonically with the increase in bed-depth regardless of the size of GAC particles. It is also observed that the iron removing capacity decreases drastically with the increase in the size of GAC particles for any fixed bed-depth. Finally the porosity of GAC particles is found to affect the iron removing capacity. The higher the GAC porosity the higher is the iron removing capacity over the considered porosity-range. It is believed that the observations of present study would be useful in adjusting GAC-bed characteristics at the time of designing household water-filters to maintain iron at the required-level.</p><p>Chemical Engineering Research Bulletin 18(2015) 1-5</p>

scholarly journals Co-Pyrolysis and Co-Gasification of Coal and Biomass in a Pressurized Fixed-Bed Reactor

1998 ◽  
Author(s):  
Anne-Gaëlle Collot ◽  
Athanasios Megaritis ◽  
Alan A. Herod ◽  
Denis R. Dugwell ◽  
Raphael Kandiyoti
Keyword(s):  
Synergistic Effects ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Birch Wood ◽  
Total Volatile ◽  
Volatile Release ◽  
Char Reactivity ◽  
Individual Contributions ◽  
The Individual ◽  
Isothermal Combustion

The co-processing of coal-biomass mixtures under inert and reducing atmospheres has been studied in a bench scale fixed-bed (‘hot-rod’) reactor. The aim was to look for evidence of synergistic effects during the co-gasification of coal and biomass. Total volatile release, tar and char yields from mixtures of Daw Mill coal and Silver Birch wood (alone and in mixtures of 25, 50 and 75 % by weight), have been determined as a function of temperature (850 and 1000 °C) and pressures (up to 25 bar) under He-pyrolysis and CO2-gasification conditions. The total volatile yields of mixtures have been found to match those calculated theoretically from pure coal and biomass values under all conditions attempted, thus suggesting a lack of synergy in the amount of char produced. However, char reactivity measurements in an atmospheric thermogravimetric analyser (isothermal combustion in air at 500 °C) indicate that chars of coal-biomass mixtures have higher combustion reactivities than would be expected from the reactivities of the raw fuels alone. Similarly, the tar yields from mixtures are also somewhat higher than those predicted from the individual contributions of coal and biomass.

Isoprene and Rubber. XVII. The Fractionation of Balata

1930 ◽  
Vol 3 (3) ◽  
pp. 511-515
Author(s):  
H. Staudinger ◽  
H. F. Bondy
Keyword(s):  
Molecular Weight ◽  
Natural Products ◽  
High Molecular Weight ◽  
Homologous Series ◽  
Chemical Properties ◽  
Uniform Size ◽  
Gutta Percha ◽  
Synthetic Materials ◽  
The Individual ◽  
Physical And Chemical

Abstract On the basis of earlier experiments with synthetic materials, compounds of high molecular weight are not composed of a single substance, but consist of a mixture of homologous polymers. The individual members of a polymeric homologous series differ very little in physical and chemical properties, and therefore a mixture of polymeric homologous products such as is obtained in the polymerization of the monomer cannot as a rule be decomposed into simple compounds by means of solvents, but merely into mixtures of products of low and high molecular weight. Such separations have been carried out, for example, in the case of polyvinylace-tates, polystyrols, polyindenes, polyanetholes, and polyethyleneoxides. On the basis of these experiments it was assumed that natural products of high molecular weight likewise consist of a mixture of polymeric homologs. Thus purified rubber, for example, according to our views is not such a completely homogeneous hydrocarbon that all the molecules have the same length, but consists of a mixture of perhaps 100 or more polymeric homologs. Pummerer's decomposition of rubber into sol,- and gel-rubber, according to our experiments, is due to the fact that rubber consists of easily soluble polyprenes and difficultly soluble polyprenes, all belonging to the same polymeric homologous series. Of course there is the possibility that, in forming compounds of high molecular weight, nature produced primary molecules of uniform size, and that the mixture of polymeric homologs was formed only later through decomposition. In that case the natural products would differ in constitution from the synthetic material. They would not be polymerically uniform but completely uniform compounds in the sense of classical organic chemistry. The fact that in life processes methods are possible which we cannot realize in the laboratory is well known. Such a finding would not, of course, contradict our former view that natural products, such as rubber and balata, are of high molecular weight in the sense of classical structural chemistry. Our former work has indicated a similar structure for rubber and gutta-percha. Here it is simply a question whether or not the macromolecules of these natural products have a uniform length. In order to reach a decision, we first of all investigated balata, since it is prepared pure more easily than rubber. It was made from balata latex which was supplied to us through the courtesy of the management of the Norddeutsche Seekabelwerke, Nordenham." The balata thus obtained is a flocculent, cellulose-like mass, which looks like gutta-percha and crystallizes like it.

Hypermodified alkali-stable dinucleotide sequences in each of the high-molecular-weight (26S and 18S) ribosomal RNA species of wheat

1977 ◽  
Vol 55 (5) ◽  
pp. 582-586 ◽  
Author(s):  
M. W. Gray ◽  
R. S. Cunningham
Keyword(s):  
Molecular Weight ◽  
Ribosomal Rna ◽  
18S Rrna ◽  
28S Rrna ◽  
Animal Cells ◽  
Wheat Embryo ◽  
Rrna Species ◽  
Wheat Embryos ◽  
The Individual ◽  
26S Rrna

Two hypermodified, alkali-stable dinucleotide sequences, each containing abase modification in addition to sugar methylation, are known to be present in wheat embryo 26S + 18S rRNA (Gray, M. W. (1974) Biochemistry 13, 5453–5463). Quantitative analysis of unfractionated 26S + 18S rRNA had suggested that each of these sequences (Cm-ψp and ψm-Ap, where Cm = O2′-methylcytidine and ψm = O2′-methylpseudouridine) was present in either the 18S or the 26S rRNA species, but not in both, at a frequency of not more than once per chain. In the study reported here, the individual 32P-labeled 18S and 26S rRNA species were isolated from viable wheat embryos germinated in the presence of [32P]orthophosphate. From analyses of phosphodiesterase and alkaline hydrolysates of the separated [32P]RNAs, we conclude that ψm-Ap is confined to wheat cytosol 18S rRNA, whereas Cm-ψp is localized in wheat cytosol 26S rRNA. The presence of ψm in the 18S rRNA of wheat stands in contrast with the situation in animal cells, where this hypermodified nucleoside is located in the 28S rRNA (Khan, M. S. N. &Maden, B. E. H. (1976) J. Mol. Biol. 101, 235–254)

scholarly journals Two-dimensional iodopeptide mapping demonstrates that erythrocyte Rh D, c, and E polypeptides are structurally homologous but nonidentical

Blood ◽  
1988 ◽  
Vol 72 (4) ◽  
pp. 1424-1427
Author(s):  
D Blanchard ◽  
C Bloy ◽  
P Hermand ◽  
JP Cartron ◽  
AM Saboori ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Molecular Species ◽  
Two Dimensional ◽  
Structural Homology ◽  
Composite Pattern ◽  
Rh Proteins ◽  
The Individual ◽  
High Degree

The 32,000 molecular weight (mol wt) erythrocyte Rh D, c, and E polypeptides were separately purified from cDE/cDE erythrocytes by monoclonal immunoprecipitations and compared by two-dimensional iodopeptide mapping. Digestions of the isolated Rh polypeptides with alpha-chymotrypsin revealed a high degree of structural homology between c and E (13/14 iodopeptides were identical) and less striking homology between D and c or E (8/19 identical). The iodopeptide maps of Rh proteins purified by a nonimmunologic protocol from cDE/cDE erythrocytes were virtually identical to the composite pattern (D + c + E) deduced from the individual maps of Rh D, c, and E iodopeptides. Digestions of the isolated Rh polypeptides with trypsin revealed an overall homology of approximately 50% between iodopeptides derived from D, c, and E. These data indicate that the erythrocyte Rh D, c, and E antigens are carried by homologous but distinct molecular species; c and E appear more closely related to each other than to D.

Properties and characteristics of partly purified glutamate dehydrogenase from sheep rumen mucosa

1981 ◽  
Vol 46 (11) ◽  
pp. 2766-2773
Author(s):  
Katarína Holovská ◽  
Viera Lenártová ◽  
Ivan Havassy
Keyword(s):  
Molecular Weight ◽  
Glutamate Dehydrogenase ◽  
Polyacrylamide Gel Electrophoresis ◽  
Enzymatic Reaction ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Ph Optimum ◽  
Relative Molecular Weight ◽  
Sheep Rumen ◽  
The Individual

The purification of glutamate dehydrogenase from sheep rumen mucosa on DEAE-cellulose afforded two enzyme fractions with glutamate dehydrogenase activity. The enzyme fraction II (tissue glutamate dehydrogenase) was freed of contaminating proteins in the subsequent purification step on Sephadex G-200. The approximate relative molecular weight (260 000) of tissue glutamate dehydrogenase (fraction II) was determined by gel filtration on Sephadex G-200 and the approximate relative molecular weight of its polypeptide chain (48 000) was established by polyacrylamide gel electrophoresis in SDS. The pH-optimum of fraction II was 7.9. The effect of substrate concentration on the rate of the enzymatic reaction was examined and the following apparent Michaelis' constants were found for the individual substrates: NADH 6.25 . 10-5 mol/l, 2-oxoglutarate 4.5 . 10-3 mol/l, and NH4+ 77 . 10-3 mol/l.

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