Selected Metal Salts Research Articles

Tailoring C─N Containing Compounds into Carbon Nanomaterials with Tunable Morphologies for Electrocatalytic Applications.

Carbon materials with unique sp2 -hybridization are extensively researched for catalytic applications due to their excellent conductivity and tunable physicochemical properties. However, the development of economic approaches to tailoring carbon materials into desired morphologies remains a challenge. Herein, a convenient "bottom-up" strategy by pyrolysis of graphitic carbon nitride (g-C3 N4 ) (or other carbon/nitrogen (C, N)-enriched compounds) together with selected metal salts and molecules is reported for the construction of different carbon-based catalysts with tunable morphologies, including carbon nano-balls, carbon nanotubes, nitrogen/sulfur (S, N) doped-carbon nanosheets, and single-atom catalysts, supported by carbon layers. The catalysts are systematically investigated through various microscopic, spectroscopic, and diffraction methods and they demonstrate promising and broad applications in electrocatalysis such as in the oxygen reduction reaction and water splitting. Mechanistic monitoring of the synthesis process through online thermogravimetric-gas chromatography-mass spectrometry measurements indicates that the release of C─N-related moieties, such as dicyan, plays a key role in the growth of carbon products. This enables to successfully predict other widely available precursor compounds beyond g-C3 N4 such as caffeine, melamine, and urea. This work develops a novel and economic strategy to generate morphologically diverse carbon-based catalysts and provides new, essential insights into the growth mechanism of carbon nanomaterials syntheses.

Revolutionizing Porous Liquids: Stabilization and Structural Engineering Achieved by a Surface Deposition Strategy.

Facile approaches capable of constructing stable and structurally diverse porous liquids (PLs) that can deliver high-performance applications are a long-standing, captivating, and challenging research area that requires significant attention. Herein, a facile surface deposition strategy is demonstrated to afford diverse type III-PLs possessing ultra-stable dispersion, external structure modification, and enhanced performance in gas storage and transformation by leveraging the expeditious and uniform precipitation of selected metal salts. The Ag(I) species-modified zeolite nanosheets are deployed as the porous host to construct type III-PLs with ionic liquids (ILs) containing bromide anion , leading to stable dispersion driven by the formation of AgBr nanoparticles. The as-afforded type-III PLs display promising performance in CO2 capture/conversion and ethylene/ethane separation. Property and performance of the as-produced PLs can be tuned by the cation structure of the ILs, which can be harnessed to achieve polarity reversal of the porous host via ionic exchange. The surface deposition procedure can be further extended to produce PLs from Ba(II)-functionalized zeolite and ILs containing [SO4 ]2- anion driven by the formation of BaSO4 salts. The as-produced PLs are featured by well-maintained crystallinity of the porous host, good fluidity and stability, enhanced gas uptake capacity, and attractive performance in small gas molecule utilization.

Synthesis of metalloporphyrin complexes based on chlorophyllin

The production of active metal complexes as a source of micronutrients is still highly desirable. In this study, metalloporphyrin compounds (i.e., iron, magnesium, and zinc) were obtained by modifying sodium-copper chlorophyllin. Metalloporphyrins were prepared by a multi-step process involving protonation of sodium-copper chlorophyllin, followed by complexation of porphyrin with selected metal salts in a DMSO solution. The selected metalloporphyrins were analysed in terms of stability, metal content, and process yield using UV-Vis, FT-IR, and ASA methods. Analysis of the influence of the pH of the complexing system and the molar ratio of chlorophyllin and metals showed that it is possible to obtain metalloporphyrins of Mg, Zn, and Fe with metal bonding efficiencies of 20, 40, and 90%, respectively. The type of acid, its concentration, and the type of salt used in the processes were also critical factors in the protonation of porphyrin as well as the efficiency of metal-porphyrin bonding.

Effect of Selected Metal Salts on the Microscopical Feature of Initial Carious - Like Lesion of Permanent Teeth (AN IN VITRO STUDY)

This study was designed to assess the microscopical changes of the enamel surfacebefore and following the treatment with different concentration of metal salts,involving zinc, strontium, magnesium, in addition to stannous fluoride and de-ionizedwater as the control.Microscopic examination was conducted on teeth samples before and followingpH-cycling procedure and following the treatment with the selected metal salt underpolarized microscope (100X).The best obvious remineralization was found following treatment with stannousfluoride, followed by zinc chloride. Samples treated with strontium chloride showedrather poorly mineralized surfaces. No signs of mineralization were observed forsamples treated with magnesium chloride.Although stannous fluoride was the best in the remineralization of initial caries,results for other metals seem to be promising if used for prevention of dental caries

Influence of lower rim C-methyl group on crystal forms and metal complexation of resorcinarene bis-crown-5

C-Methyl resorcinarene bis-crown-5 (1) with pendant methyl groups at the lower rim was prepared and crystallized in various solvent mixtures with and without selected metal salts. The crystal structures of two polymorphic forms of unsolvated 1 (1-I and 1-II), three solvates (acetonitrile, chloroform and dichloromethane–methanol), and three metal complexes with silver and cesium salts were obtained. The lower rim methyl groups and the block shape of the host promote crystal packing in brick-wall type assemblies, in which the binding cavities are efficiently filled by the crown bridges. Thus, solvents are found in the interstitial space or coordinated to the crown bridges on top of the cavity, whereas more strongly binding metal cations are able to occupy the cavity. The chloroform solvate proved to be a relatively labile crystal form, which transformed to unsolvated form (1-I) over time. Resorcinarene mono-crown-5 (2) was obtained as a minor product of the bridging reaction. Two solvate structures (acetonitrile and chloroform–water) of 2 are also reported, providing an example of the effect of the missing crown bridge on the solvate structures.

Translational responses and oxidative stress of mussels experimentally exposed to Hg, Cu and Cd: One pattern does not fit at all

Certain metals, like Hg, Cu and Cd, are capable of down-regulating protein synthesis in several marine organisms, including Mytilus galloprovincialis. Nevertheless, due to the complexity of the environmental stress, it is difficult to evaluate the influence of individual metals on protein synthesis via field studies. To bypass this difficulty, experimental studies were carried out on M. galloprovincialis exposed in aquarium for 15 days to one of three selected metal salts, HgCl 2, CuCl 2 and CdCl 2. Polysome profile was determined in digestive gland extracts of the exposed mussels as a way of measuring the functional status of ribosomes, superoxide radical production and lipid peroxidation as indicators of oxidative stress, metallothionein content as a metal detoxification index, and superoxide dismutase activity as a free radicals-scavenging index. Exposure of mussels to Hg 2+ or Cu 2+ resulted in a concentration- and time-dependent decrease in the polysome content of digestive gland cells, which at 15th day of exposure and at the highest metal concentrations tested, was 32% and 19% of the control, respectively. Both metals, at the concentrations used (<40 μg/L), did not significantly influence the oxidative stress biomarkers. By contrast, Cd 2+ treatment significantly induced superoxide radical production and lipid peroxidation in digestive gland cells, hinting that mussels suffered from oxidative stress. Polysome levels in Cd 2+-exposed mussels were initially decreased by day 5 in digestive gland cells and then elevated to reach nearly the control levels by 15 days of exposure. Elevated protein synthesis was associated with significantly increased production of metallothioneins, whereas such increase was not recorded in Hg 2+- or Cu 2+-exposed mussels. Interestingly, the ribosome efficiency at initiating protein synthesis followed a similar pattern of polysome alterations, a fact suggesting that regulation of protein synthesis mainly occurred at the initiation phase of translation. Overall, these results suggest that the effect of each metal on protein synthesis is idiosyncratic and depends on its ability to induce specific cellular defense mechanisms against oxidative stress.

2-Pyridylmethylphosphonic acid: a flexible, multi-dentate ligand for metal phosphonates

In a systematic investigation, 2-pyridylmethylphosphonic acid, 2PyCH2PO3H2 (Py = pyridine), was reacted with specifically selected metal salts to examine the influence of the preferred metal geometry, role of the anion and coordination preferences of the ligand. From this study a series of metal phosphonates were isolated: [{M(2PyHCH2PO3H)(H2O)}ClO4]n, M = Mn, 1 and Co, 2; a tetranuclear iron phosphonate cage, [Fe4(2PyHCH2PO3)4(H2O)12(Cl)(ClO4)7·xH2O], 3, and two polymeric iron phosphonate chains: 4, [Fe2(2PyHCH2PO3H)2(ClO4)]n, and 5, [Fe(2PyHCH2PO3H)(H2O)(ClO4)]n. Meanwhile, the stoichiometric reaction of Pb(NO3)2 and Ag(SO3CF3) with 2PyCH2PO3H2 afforded a bimetallic Ag/Pb network, 6, [AgPb(2PyCH2PO3)(NO3)]n. The individual components of this reaction, Pb(NO3)2 and Ag(SO3CF3), when reacted with 2PyCH2PO3H2 yielded [Pb(2PyHCH2PO3H)(NO3)2]n, 7, and a luminescent silver polymer 8, [Ag3(2PyHCH2PO3)(SO3CF3)2]n, that are used for structural comparison to 6. All products were characterized in the single crystal and bulk form. The electrochemical properties of 1, 2 and 3 were studied, and X-ray photoelectron spectroscopy (XPS) employed to investigate the bimetallic polymer, 6, and the tetrameric iron phosphonate, 3.

Starch–metal complexes and their rheology

AbstractChanges in conductivity of 5 w/w% starch gels was studied on their titration with 0.1 M aqueous solutions of selected metal salts. Starch gels usually trapped around 10 mg metal ions per 1 g starch [Co(II), Cu(II), Fe(III), Ni(II)] and that value was only slightly dependent on starch origin (amaranthus, corn, potato, tapioca, waxy corn). Among salts studied (acetates, chlorides, nitrates) FeCl3 and NiCl2 were likely to be used because they hydrolyzed increasing conductivity of the solutions and formed micelles of corresponding hydroxides adhering to starch micelles and increasing amount of trapped metal. Addition of metal salts to starch gels had a devastating effect on pseudoplasticity and viscosity of starch gels and only potato starch gel was to a certain extent, exceptional in that respect.

Polyaniline Nanofibers: A Unique Polymer Nanostructure for Versatile Applications

Known for more than 150 years, polyaniline is the oldest and potentially one of the most useful conducting polymers because of its facile synthesis, environmental stability, and simple acid/base doping/dedoping chemistry. Because a nanoform of this polymer could offer new properties or enhanced performance, nanostructured polyaniline has attracted a great deal of interest during the past few years. This Account summarizes our recent research on the syntheses, processing, properties, and applications of polyaniline nanofibers. By monitoring the nucleation behavior of polyaniline, we demonstrate that high-quality nanofibers can be readily produced in bulk quantity using the conventional chemical oxidative polymerization of aniline. The polyaniline nanostructures formed using this simple method have led to a number of exciting discoveries. For example, we can readily prepare aqueous polyaniline colloids by purifying polyaniline nanofibers and controlling the pH. The colloids formed are self-stabilized via electrostatic repulsions without the need for any chemical modification or steric stabilizer, thus providing a simple and environmentally friendly way to process this polymer. An unusual nanoscale photothermal effect called "flash welding", which we discovered with polyaniline nanofibers, has led to the development of new techniques for making asymmetric polymer membranes and patterned nanofiber films and creating polymer-based nanocomposites. We also demonstrate the use of flash-welded polyaniline films for monolithic actuators. Taking advantage of the unique reduction/oxidation chemistry of polyaniline, we can decorate polyaniline nanofibers with metal nanoparticles through in situ reduction of selected metal salts. The resulting polyaniline/metal nanoparticle composites show promise for use in ultrafast nonvolatile memory devices and for chemical catalysis. In addition, the use of polyaniline nanofibers or their composites can significantly enhance the sensitivity, selectivity, and response time of polyaniline-based chemical sensors. By combining straightforward synthesis and composite formation with exceptional solution processability, we have developed a range of new useful functionalities. Further research on nanostructured conjugated polymers holds promise for even more exciting discoveries and intriguing applications.

In Vitro Comparative Kinetic Analysis of the Chloroplast Toc GTPases

A unique aspect of protein transport into plastids is the coordinate involvement of two GTPases in the translocon of the outer chloroplast membrane (Toc). There are two subfamilies in Arabidopsis, the small GTPases (Toc33 and Toc34) and the large acidic GTPases (Toc90, Toc120, Toc132, and Toc159). In chloroplasts, Toc34 and Toc159 are implicated in precursor binding, yet mechanistic details are poorly understood. How the GTPase cycle is modulated by precursor binding is complex and in need of careful dissection. To this end, we have developed novel in vitro assays to quantitate nucleotide binding and hydrolysis of the Toc GTPases. Here we present the first systematic kinetic characterization of four Toc GTPases (cytosolic domains of atToc33, atToc34, psToc34, and the GTPase domain of atToc159) to permit their direct comparison. We report the KM, Vmax, and Ea values for GTP hydrolysis and the Kd value for nucleotide binding for each protein. We demonstrate that GTP hydrolysis by psToc34 is stimulated by chloroplast transit peptides; however, this activity is not stimulated by homodimerization and is abolished by the R133A mutation. Furthermore, we show peptide stimulation of hydrolytic rates are not because of accelerated nucleotide exchange, indicating that transit peptides function as GTPase-activating proteins and not guanine nucleotide exchange factors in modulating the activity of psToc34. Finally, by using the psToc34 structure, we have developed molecular models for atToc33, atToc34, and atToc159G. By combining these models with the measured enzymatic properties of the Toc GTPases, we provide new insights of how the chloroplast protein import cycle may be regulated.

Complexes of amylose and amylopectins with multivalent metal salts

Metal cations [Cu(II), Fe(III), Mn(II), and Ni(II)] are ligated by amylose as well as potato, and corn amylopectins as proven by electron paramagnetic resonance spectra and conductivity measurements. The hydroxyl groups of polysaccharides are the coordination sites. Isolated starch polysaccharides did not coordinate to metal ions so well as starch did. The resulting polycenter Werner complexes were mainly square planar species. The ligation of the central metal atoms resulted in a variation of the thermal stability, pathway, and rate of thermal decomposition of starch as proven by thermogravimetric (TG, DTG) and scanning differential calorimetric measurements. Frequently, amylose and potato amylopectin willingly formed clathrates in which the water molecules were caged. The mode of the coordination of the hydroxyl groups to the central metal atom controlled the clathrate formation from amylose and in the case of potato amylopectin metal atoms bound to the phosphoric acid moiety formed cage by coordination of the hydroxyl groups to them. Coordination to selected metal salts controls pathway and products of polysaccharide ligand thermolysis.

Thermal properties of complexes of amaranthus starch with selected metal salts

Metal cations (Cu(II), Fe(III), Mn(II), and Ni(II)) are ligated by amaranthus starch as proven by EPR spectra and conductivity measurements. The hydroxyl groups of starch are the coordination sites. The acetate and nitrate anions of the metal salts behave as bidentate ligands and reside in the inner coordination sphere of resulting polycenter Werner complexes. There is only a weak degeneration of orbitals of central metal ions caused by a shift of unpaired spin from the central atom to the ligand. The ligation of the central metal atoms resulted in a variation of the thermal stability, pathway, and rate of thermal decomposition of starch as proven by thermogravimetric (TG) and differential scanning calorimetric (DSC) measurements.

Influence of lead acetate and selected metal salts on tryptophan binding to rat hepatic nuclei.

This study evaluated whether lead acetate or other selected metal salts would influence the binding of L-tryptophan to rat hepatic nuclei. Lead salts and other salts of cadmium, zinc, mercury, and molybdenum, when added alone, had only small effects on 3H-tryptophan binding to hepatic nuclei in vitro. However, each of these salts, when added along with unlabeled L-tryptophan (excess, 10(-4) M), caused significantly less inhibition of 3H-tryptophan binding to hepatic nuclei than did unlabeled L-tryptophan alone. Lead acetate (10(-10) to 10(-4) M), when added along with unlabeled L-tryptophan, abrogated the inhibition of binding related to unlabeled L-tryptophan alone. Sodium arsenite (but not potassium arsenate) as well as sodium selenite (at 10(-4) M concentrations) inhibited to a moderate degree the in vitro 3H-tryptophan binding to hepatic nuclei, but addition of 10(-4) dithiothreitol, a protective agent for sulfhydryl groups, diminished this inhibition. Rats receiving a high dose of lead acetate before being tube-fed L-tryptophan displayed a decrease in hepatic protein synthesis compared with the stimulatory response connected with L-tryptophan alone. Thus, the addition of lead acetate and of other metal salts appears to have an inhibitory effect on L-tryptophan binding to hepatic nuclei. Lead acetate was investigated in in vivo experiments and was found to negate the stimulation of hepatic protein synthesis related to L-tryptophan alone.

In Vitro Effects of Various Metals on Natural Killer Cell Activity in Cultured Human Lymphocytes

Heavy metals have been shown to have a differential effects on various aspects of immune response. Recently natural killer cells have been widely investigated due to their purported role in immune surveillance. To ascertain the immunotoxic effects of lead, cadmium, nickel and chromium on natural killer (NK) cell activity in vitro, peripheral blood lymphocytes from normal donors were examined in the presence of different concentrations (10−5-10−8 M) of four selected metal salts (cadmium sulphate, lead nitrate, chromium nitrate and nickel sulphate). NK cell activity was evaluated in a 4-h chromium release assay against K562 target cells. All of the metal salts were found to exert no effect on NK cell function in the human concentration range.

Genotoxicity biomarkers in the assessment of heavy metal effects in mussels: Experimental studies

Heavy metals are stable and persistent environmental contaminants. The range of metal concentrations is generally below acute thresholds in coastal areas, where recognition of chronic sublethal effects is more relevant. Evidence of long-term adverse effects, such as cancer, due to heavy metals in marine animals comes from a number of field and experimental studies. The mechanism of metal carcinogenicity remains largely unknown, although several lines of experimental evidence suggest that a genotoxic effect may be involved. The aim of our study was to evaluate the sensitivity of genotoxicity tests, alkaline elution and micronucleus test, as biomarkers for the detection of heavy metals in mussels as the sentinel species. Experimental studies were carried out on Mytilus galloprovincialis exposed in aquarium (5 days) to different concentrations of three selected metal salts, CuCl2 (5, 10, 20, 40, 80 µg/l/a), CdCl2 (1.84, 18.4, 184 µg/l/a), and HgCl2 (32 µg/l/a), and to a mixture of equimolar doses of the three metals to study the results of their joint action. Metallothionein quantitation was used as a marker of metal exposure. Lysosomal membrane stability was applied to evaluate the influence of physiological status on genotoxic damage. The ranking of genotoxic potential was in decreasing order: Hg > Cu > Cd. Cu and Hg caused an increase of DNA single-strand breaks and micronuclei frequency. Cd induced a statistical increase of DNA damage, but gave negative results with the micronucleus test. A relationship between genotoxic effects and metallothionein content was observed. Reduction in lysosomal membrane stability with the increasing concentration of heavy metals was also evident. Environ. Mol. Mutagen. 33:287–292, 1999 © 1999 Wiley-Liss, Inc.

Genotoxicity biomarkers in the assessment of heavy metal effects in mussels: Experimental studies

Heavy metals are stable and persistent environmental contaminants. The range of metal concentrations is generally below acute thresholds in coastal areas, where recognition of chronic sublethal effects is more relevant. Evidence of long-term adverse effects, such as cancer, due to heavy metals in marine animals comes from a number of field and experimental studies. The mechanism of metal carcinogenicity remains largely unknown, although several lines of experimental evidence suggest that a genotoxic effect may be involved. The aim of our study was to evaluate the sensitivity of genotoxicity tests, alkaline elution and micronucleus test, as biomarkers for the detection of heavy metals in mussels as the sentinel species. Experimental studies were carried out on Mytilus galloprovincialis exposed in aquarium (5 days) to different concentrations of three selected metal salts, CuCl2 (5, 10, 20, 40, 80 micrograms/l/a), CdCl2 (1.84, 18.4, 184 micrograms/l/a), and HgCl2 (32 micrograms/l/a), and to a mixture of equimolar doses of the three metals to study the results of their joint action. Metallothionein quantitation was used as a marker of metal exposure. Lysosomal membrane stability was applied to evaluate the influence of physiological status on genotoxic damage. The ranking of genotoxic potential was in decreasing order: Hg > Cu > Cd. Cu and Hg caused an increase of DNA single-strand breaks and micronuclei frequency. Cd induced a statistical increase of DNA damage, but gave negative results with the micronucleus test. A relationship between genotoxic effects and metallothionein content was observed. Reduction in lysosomal membrane stability with the increasing concentration of heavy metals was also evident.

The ecotoxicity and the biodegradability of lactic acid, alkyl lactate esters and lactate salts

The ecotoxicity of lactic acid, its alkyl esters and selected metal salts was studied experimentally with the micro alga Selenastrum capricornutum, the crustacean Daphnia magna and the fish species Brachydanio rerio and Pimephales promelas. In addition, the biodegradation of lactate esters was also studied. The aim of the study was to provide predicted environmental data for additional alkyl homologues and metal salts. The ecotoxicity data are evaluated by means of Structure Activity Relations (SAR), using literature data on a nonpolar narcotic mechanism of toxicity as a baseline for comparison. Lactate salts were evaluated by comparison to the toxicity of the metal ion. For the fish and D. magna, it was evident that methyl, ethyl, propyl and to a lesser extent butyl lactate were slightly more toxic in comparison to baseline non-polar narcotic toxicity data. The toxicity tests carried out with lactate-salts demonstrated clearly that the toxicity in standard tests is only determined by the associated cation and not by the lactate part. Lactic acid and its alkyl esters were degraded for more than 60% in the ready biodegradability tests and from the data presented, it is evident that the majority of alkyl lactates are readily biodegradable. The results presented in this study indicate that alkyl lactate esters show some differences in their ecotoxicity when compared to non polar narcotic compounds in but that these differences are generally small. When aquatic toxicity is considered together with their rapid tendency to biodegrade, it is concluded that lactate esters show generally favourable environmental characteristics.

Contribution to the reaction kinetics of water soluble aerosols and SO 2 in air at PPM concentrations

A laboratory study of the heterogeneous catalysis of sulfur dioxide in the atmosphere involved the determination of the rate of atmospheric oxidation of sulfur dioxide to sulfuric acid in the presence of aerosols which were selected metal salts previously reported to act as catalysts. A new aerosol stabilizing technique was developed in which aerosol particles were deposited on inert supporting Teflon beads. The deposition was carried out in a fluidized-bed to ensure discrete aerosol deposition and to achieve a uniform distribution of aerosol concentration on the supporting beads. Because neither the physical shape of the aerosol nor their chemical properties were altered by the stabilizing process, kinetic data obtained in the laboratory by using stabilized aerosols can be extrapolated to describe reactions which may occur in the atmospheric environment. Teflon beads with deposited aerosol particles were packed into a flow reactor. The catalytic oxidation of sulfur dioxide occurred within the reactor as sulfur dioxide gas in humid air mixture flowed through it. The reactor influent sulfur dioxide concentrations ranged from 3 to 18 ppm. Progress of the chemical reaction was continuously monitored by determining the sulfur dioxide concentrations in the reactor effluent with a microcoulometer. Reaction products were identified and quantified by analyzing the reactor contents after the completion of an experimental run. It was observed that higher rates of sulfur dioxide oxidation were always associated with higher relative humidities of the air mixture. Because aerosol particles hydrated into solution drops at high relative humidities, the predominant mass transfer mechanism was absorption of sulfur dioxide by aqueous catalyst drops accompanied by chemical reaction in the liquid phase. Experimental results indicated that the over-all rate of reaction was controlled by the chemical reaction. Milligram for milligram, aerosols of MnSO 4, MnCl 2, and CuSO 4 were found to be 12.2, 3.5, and 2.4 times as effective as NaCl aerosol in promoting the oxidation of sulfur dioxide. CuCl 2 aerosol acted as a reactant in its reaction with sulfur dioxide; sulfur dioxide was oxidized to sulfuric acid while CuCl 2 was reduced CuCl. When MnSO 4 aerosol was used as catalyst, a reaction rate equation was derived which showed that the over-all reaction rate was first order with respect to the sulfur dioxide concentration in the gas phase. By extrapolating laboratory results to the industrial atmospheric environment, the rate of oxidation of sulfur dioxide in natural fog was estimated to be 2 per cent h /t-1.

Study of degradation of polyphosphates in aqueous solution

AbstractCyclic trimetaphosphate is formed along with monophosphate and some di‐ and triphosphate on the degradation of chainlike polyphosphates in aqueous solution at pH 8 and 60°C. This degradation is catalytically accelerated by many metal salts. The kinetic examination of the degradation reaction in the presence of some selected metal salts shows that its catalytic effect is closely connected with the ion exchange capacity of the polyphosphates. The higher the affinity of a metal cation to the polyphosphate, i.e., the stronger it is bound, the higher is its catalytic activity. This increases in the order K &lt; Na &lt; Li &lt; Ba &lt; Sr &lt; Ca &lt; Mg &lt; Al. From the kinetics of the degradation reaction it follows, contrary to our previous investigations, that degradation does not occur only from the chain end but statistically over the whole polymer molecule and that the formation of trimetaphosphate is not connected with the formation of the monophosphate. A new scheme of reaction for the formation of the cyclic trimetaphosphate from the chainlike polyphosphates is developed. According to this the primary step of the degradation consists of an intramolecular “phosphorylation” of the polyphosphate, which is then followed by hydrolysis of the trimetaphosphate.