Studies in the stereochemistry of zinc(II). VII. Zinc complexes with dialkyldithiophosphates

1970 ◽  
Vol 23 (10) ◽  
pp. 1989 ◽  
Author(s):  
DR Dakternieks ◽  
DP Graddon
Keyword(s):  
Molecular Weight ◽  
Zinc Complexes ◽  
Weight Data ◽  
Infrared Data

A series of bis(O,O-dialkyldithiophosphato)zinc(11) complexes, ZnL2 (LH = (R0)2PS2H; R = Et, Pri, Bu, Bui, Bus, cyclohexyl), has been isolated. Pyridine adducts ZnL2(py)2 (R = Et, Pr, Pri, Bui) and ZnL2(py) (R = Pr, Pri, Bui) have also been obtained. Basic complexes ZnO,3ZnL2 (R = Et, Pr) have been isolated. Molecular weight data show that ZnL2 associates in benzene. When R = Pri 2ZnL2 ↔ Zn2L4 ΔG0c -6kJ mol-1 The adducts ZnL2(py) are stable. Adducts ZnL2(py)2 dissociate in benzene; when R = Pr ZnL2(py) + PY + ZnL2(py)2 ΔG0c-7kJmol-1 (ΔG0 calculated from molal concentrations). Infrared data cannot distinguish between chelate, bridging, and unidentate PS2 groups. Co-crystallization of ZnL2(py)2 and XiL2(py)2 could not be achieved, suggesting ZnL2(py)2 is cis-octahedral.

Organomercury compounds. XXIII. Organomercuric Quinolin-8-olates

1978 ◽  
Vol 31 (3) ◽  
pp. 527 ◽  
Author(s):  
RJ Bertino ◽  
GB Deacon ◽  
JM Miller
Keyword(s):  
Mass Spectrometry ◽  
Molecular Weight ◽  
Solid State ◽  
Carbon Tetrachloride ◽  
Crystal Structures ◽  
Supporting Evidence ◽  
Visible Spectroscopy ◽  
Organomercury Compounds ◽  
Weight Data

The complexes RHg(ox) (R = C6F5, p-HC6F4, or p-MeOC6F4; ox = quinolin-8- olate) have been prepared by reaction of thallous quinofin-8-olate with the appropriate organomercuric chlorides whilst PhHg(ox or meox), MeHg(ox),H2O, and MeHg(meox) (meox = 2-methylquinolin-8-olate) have been obtained from phenyl- or methyl-mercuric hydroxide and quinolin-8-ol or 2-methyl-quinolin-8-ol. Although MeHg(ox),H2O was readily dehydrated, the water could not be displaced by ligands (e.g. Ph3PO, Me2SO). Chelation of the quinolin-8-olate ligands (rather than unidentate O- bonding) was established for all complexes by ultraviolet/visible spectroscopy. Molecular weight data indicated that all complexes except MeHg(ox) and MeHg(ox),H2O are partly associated in benzene, chloroform and/or carbon tetrachloride [K(2 monomer ↔ dimer) in the range 1-40 mol-1 dm3]; this suggests an associated structure in the solid state. Some supporting evidence for associated structures was obtained by mass spectrometry. The structural conclusions are discussed in the light of crystal structures of PhHg(ox) and PhHg(meox) carried out in a concurrent investigation.

IV. The Micellar Theory of the Structure of Rubber

1942 ◽  
Vol 15 (3) ◽  
pp. 446-451
Author(s):  
G. Gee
Keyword(s):  
Molecular Weight ◽  
Physical Properties ◽  
Infinite Dilution ◽  
Mechanical Deformation ◽  
Point Of View ◽  
Pressure Measurements ◽  
Physical Behavior ◽  
Molecular Weights ◽  
Micelle Size ◽  
Weight Data

Abstract The molecular weight data reported in Part II depend on the assumption that the values obtained by extrapolating osmotic pressure measurements to infinite dilution represent true molecular weights. This point of view has been strongly criticized, particularly by Pummerer and his coworkers, according to whom rubber normally exists in solution in the form of micelles comprising more or less well-defined aggregates containing a considerable number of chemical molecules. The- osmotic “molecular weight” is then regarded as the weight of an average micelle. If they exist, these micelles may be important in determining both the chemical and physical behavior of rubber, for we should clearly expect the bonds by which the chemical molecules are bound into micelles to be weaker than those within the molecules. It may be noted that it has been shown elsewhere that the physical properties of a series of rubber fractions are closely related to their osmotic and viscosity molecular weights. Since, according to the micellar theory, these fractions can differ only in micelle size, their mechanical behavior must, from this viewpoint, be determined by the size of the micelles, which must therefore remain intact during mechanical deformation of the rubber. It is the object of the present paper to examine in more detail the basis of the micellar theory, and especially to offer an interpretation of the results of the East method, on which Pummerer's arguments are mainly based.

Coordination complexes of acetylene diphosphines. II. Diphosphine bridged palladium(II) and platinum(II) derivatives

1969 ◽  
Vol 47 (14) ◽  
pp. 2573-2578 ◽  
Author(s):  
A. J. Carty ◽  
A. Efraty
Keyword(s):  
Molecular Weight ◽  
Infrared Spectra ◽  
Coordination Complexes ◽  
Weight Data

Complexes of the type (MX2)2(DPPA)2 (M = Pd, Pt; X = Cl, Br, I, SCN; DPPA = bis(diphenylphosphino)acetylene) have been prepared and characterized. Raman, infrared, and molecular weight data have been used to show that the structures are binuclear with bridging bis(diphenylphosphino)acetylene groups. The infrared spectra of the compounds [M(SCN)2]2(DPPA)2 are suggestive of the presence of both N and S bonded thiocyanate within the same molecule.

scholarly journals Kinetics of Oxidative Depolymerization of κ-carrageenan by Ozone

2017 ◽  
Vol 12 (2) ◽  
pp. 235 ◽  
Author(s):  
Aji Prasetyaningrum ◽  
Ratnawati Ratnawati ◽  
Bakti Jos
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Second Order ◽  
Kinetics Model ◽  
Ozone Treatment ◽  
Capillary Viscometer ◽  
Number Average Molecular Weight ◽  
Constant Flow Rate ◽  
Kinetics Of ◽  
Weight Data

Depolymerization kinetics of κ-carrageenan by ozone treatment has been studied at various pHs and times. The purified κ-carrageenan with the initial molecular weight of 271 kDa was dispersed in water to form (1 % w/v) solution. Ozone with 80±2 ppm concentration and constant flow rate of 3 L.min-1 was bubbled into the κ-carrageenan solution. The experiments were conducted at pH of 3, 7, and 10 at     different times (5, 10, 15, and 20 minutes) of ozonation. The viscosity of the solution was measured   using Ubbelohde capillary viscometer, which was then used to find the number-average molecular weight by Mark-Houwink equation. The number-average molecular weight data was treated using zero, first, and the second-order reaction kinetics model, to obtain the kinetics of κ-carrageenan depolymerization. The depolymerization is assumed to occur by random scission. The results show that the kinetics rate constant of κ-carrageenan depolymerization is higher at lower pHs. The second-order model is more suitable for describing the kinetics of depolymerization of κ-carrageenan by ozonation process. The rate constants for the second-order kinetics model are 5.45×10-4 min-1, 1.27×10-4 min-1, and 7.21×10-5 min-1 for pH 3, 7, and 10, respectively. The actual values of reaction order under acid and    alkali conditions are ranging from 1.88 to 1.90. Copyright © 2017 BCREC Group. All rights reserved.Received: 21st November 2016; Revised: 27th January 2017; Accepted: 18th February 2017How to Cite: Prasetyaningrum, A., Ratnawati, R., Jos, B. (2017). Kinetics of Oxidative Depolymerization of κ-carrageenan by Ozone. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (2): 235-242 (doi:10.9767/bcrec.12.2.805.235-242)Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.805.235-242

G -Values for Scission and Crosslinking on γ — Radiolysis of Ultem at 303 K

2003 ◽  
Vol 15 (3) ◽  
pp. 259-267 ◽  
Author(s):  
Sheila Devasahayam ◽  
David J.T. Hill ◽  
Andrew K. Whittaker
Keyword(s):  
Molecular Weight ◽  
Direct Observation ◽  
Gel Permeation Chromatography ◽  
Solubility Data ◽  
Radiation Chemical ◽  
Gel Permeation ◽  
Weight Analysis ◽  
Weight Data ◽  
Soluble Fractions

The radiation chemical yields G( S) and G( X) for H-linking and Y-linking models for Ultem have been calculated from molecular weight analysis by gel permeation chromatography. These G-values have been compared with the G-values obtained from analysis of soluble fractions above the gel dose, which have been reported in previous works. An analysis of the molecular weight data in terms of H-linking and Y-linking mechanisms yielded values of G( S H) = 1.0 × 10−3 and G( H) = 6.0 × 10−3 and G( S Y) = 1.3 × 10−2 and G( Y) = 1.8 × 10−2. The corresponding values obtained from the solubility data were G( S H) = 0.53 × 10−2, G( H) = 1.39 × 10−2, G( S Y) = 4.2 × 10−2 and G( Y) = 4.6 × 10−2. The origin of the disagreement between the molecular weight and solubility values is not clear, but it could arise as a result of observed microgel formation below the reported gel dose of 0.13 MGy. Whether the crosslink mechanism proceeds by an H-linking or Y-linking process is also unclear and will require direct observation of the crosslinking structures.

LOW MOLECULAR WEIGHT HEPARINS s ORAL ABSORPTION IN MONKEYS

1987 ◽  
Author(s):  
S E Lasker ◽  
B Y Lee ◽  
R E Madden
Keyword(s):  
Molecular Weight ◽  
Oral Absorption ◽  
Average Molecular Weight ◽  
Test System ◽  
Maximum Activity ◽  
Low Molecular Weight ◽  
Low Molecular Weight Heparins ◽  
Equilibrium Ultracentrifugation ◽  
Clinical Potential ◽  
Weight Data

An orally administered low molecular weight heparin-like derivative of the commercial polydisperse polysaccharide is desirable clinically. The dissociation of antithrombotic properties and the induction of bleeding as well as minimal effect on platelet function are characteristics of some low-molecular weight heparins; however the circulating level of the anti Xa activity associated with demonstrable theraputic efficacy is not yet defined.The availability of a variety of low molecular weight heparins provided us with the opportunity to evaluate the gastrointestinal absorption characteristics of the preparations in the primate.Average molecular weight is only one of a spectrum of variables associated with absorbability, while Xa/APTT ratio differences and non-equivalent structural alterations may be responsible for functional differences in a living test system. Nevertheless, because of the clinical potential it is instructive to evaluate the GI absorbability of several preparations for which we have precise molecular weight data.Preparations: Low molecular weight heparins were prepared by a variety of methods including isolationby alcohol fractionation from broadly polydisperse commercial or crude heparins, depolymerization of commercial or crude heparin and franctionation of depolymerization products.Methods:Molecular weights were established by equilibrium ultracentrifugation and anti Xa activity was assayed by the Yin-Wessler coagulation method. Faste rhesus monkeys weighing 8-13 kg. were anesthestized and intubated with a radio opaque catheter. One cubic centimeter of a heparin preparation in saline was instilled directly into the duodenum. Blood samples assayed for anti Xa activity and thromboelasticity were drawn at periodic intervals from an indwelling femoral catheter.Results:Standard unfractionated heparin was detectable in blood only after one-half hour. The maximum activity for low molecular weight preparations was achieved after one-half to one hour.One fraction demonstrated activity in the plasma after four hours. Thedose response curve for one fraction at half-hour wascuyvilineal between 7 and 16 Mg/Kg.

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