A New Route for the Synthesis of Alkali Polyphosphate from Economical Starting Materials: Preparation and Characterization of Sodium Cyclotriphosphate

Abstract

Thermal synthesis of sodium cyclotriphosphate (SCTP) – Na₃P₃O₉ was investigated in the temperature range of 150 °C to 750 °C using sodium chloride (NaCl) and 85 wt% orthophosphoric acid (H₃PO₄) as economical starting materials. Reaction temperature had a crucial impact on the chloride elimination rate and the formation of SCTP. The best result was obtained at 600 °C with 96% of elimination of the initial chloride as hydrochloric acid and 84% of selectivity in SCTP. At lower temperatures, residual chloride contents were high. At higher temperatures (650 °C and 750 °C), SCTP was melted and transformed into glassy products.     

A New Route for the Synthesis of Alkali Polyphosphate from Economical Starting Materials: Part II—Influence of Reaction Conditions

Abstract

Direct synthesis of sodium cyclotriphosphate, Na₃P₃O₉ (SCTP), from sodium chloride and orthophosphoric acid as economical starting materials was investigated. Reaction conditions including the heating rate, reaction plateau time, air flow rate, and Na/P molar ratio were found to be key parameters for the elimination of chloride and for the selectivity in SCTP. High yields in SCTP (94–99%) were obtained. The results are very interesting with respect to a potential industrial application for the synthesis of SCTP from point of view of the low cost of the starting materials.     

Statistical mechanics of two dimensional tilings

Reduced dimensionality in two dimensions is a topic of current interest. We use model systems to investigate the statistical mechanics of ideal networks. The tilings have possible applications such as the 2D locations of pore sites in nanoporous arrays (quantum dots), in the 2D hexagonal structure of graphene, and as adsorbates on quasicrystalline crystal surfaces. We calculate the statistical mechanics of these networks, such as the partition function, free energy, entropy, and enthalpy. The plots of these functions versus the number of links in the finite networks result in power law regression. We also determine the degree distribution, which is a combination of power law and rational function behavior. In the large-scale limit, the degree of these 2D networks approaches 3, 4, and 6, in agreement with the degree of the regular tilings. In comparison, a Penrose tiling has a degree also equal to about 4.     

Reaction of lead ions with hydroxylapatite granules

In the effort to improve the performance of hydroxylapatite (HA) in removing lead ions from aqueous solutions, millimeter-sized granules with 50 % porosity were synthesized. Such HA particles, after drying at 100°C, or heating at 800°C or 1100°C, exhibited the specific surface areas of 50 m² g⁻¹, 25 m² g⁻¹, and 5 m² g⁻¹, respectively. It was found that heavy metal sorption capacity of HAs can be related to their surface area. Non-calcined granules were difficult to handle and easy to crush. Hardened granules showed heavy metal absorption on their outer surfaces. Absorption capacity of sintered HA particles towards lead was lower but adsorbed lead ions were spread inside the porous structure of HA granules more evenly. Under flow conditions, lead ions were captured by HA at a rate of 0.5 mg g⁻¹ min⁻¹. Small lead phosphate aggregates were released from the HA sorbent together with calcium ions. Size of the aggregates depended on the lead concentration and ranged from 1–50 μm in diameter; the aggregates could be removed by ultrafiltration. Results show that porous hardened HA granules can be used as an efficient phosphate source for the immobilization of lead ions from aqueous media. Organic ligands tend to interfere with the water purification procedure.     

A Unified Total Synthesis of the Actinoallolides,a Family of Potent Anti‐Trypanosomal Macrolides

Trypanosoma protozoan parasites are the causative agents of Chagas disease and sleeping sickness, two neglected tropical diseases where there is an urgent need for improved treatments and the evaluation of promising drug leads like the actinoallolides. Enabled by the highly stereocontrolled aldol reactions of three chiral ketone building blocks, an efficient first total synthesis of the potent anti‐trypanosomal macrolide (+)‐actinoallolide A has been achieved in 17 steps and 8 % overall yield. Our convergent route features an adventurous ring‐closing metathesis to form the requisite trisubstituted (8E)‐alkene in the 12‐membered macrolactone, followed by the controlled installation of the labile transannular hemiacetal. Late‐stage diversification then provides ready access to the congeneric (+)‐actinoallolides B–E.     

Magnetic interactions in spin-labelled glycine complexee to cupric ions

Summary The interactions between cupric ions and a paramagnetic aminoacid ligand labelled with a nitroxide group were investigated by visible and e.p.r. spectroscopies. Glycine substituted on the carboxylic acid function with 4-amino-2,2,6,6-tetramethylpiperidineN-oxide forms complexes with cupric ions which show strong magnetic interactions between the paramagnetic centers. At high pH values, averaged g and hyperfine coupling parameters are observed with g=2.05 and a=30 gauss, corresponding to a complex formed with two ligands coordinated to the cupric ions. The presence of other species is discussed.     

A Unified Total Synthesis of the Actinoallolides,a Family of Potent Anti-Trypanosomal Macrolides

Trypanosoma protozoan parasites are the causative agents of Chagas disease and sleeping sickness, two neglected tropical diseases where there is an urgent need for improved treatments and the evaluation of promising drug leads like the actinoallolides. Enabled by the highly stereocontrolled aldol reactions of three chiral ketone building blocks, an efficient first total synthesis of the potent anti-trypanosomal macrolide (+)-actinoallolide A has been achieved in 17 steps and 8 % overall yield. Our convergent route features an adventurous ring-closing metathesis to form the requisite trisubstituted (8E)-alkene in the 12-membered macrolactone, followed by the controlled installation of the labile transannular hemiacetal. Late-stage diversification then provides ready access to the congeneric (+)-actinoallolides B–E.     

Analysis of spin-labelled glycylglycine interactions with cupric ions

Summary Glycylglycine substituted with 4-amino-2,2,6,6-tetramethyl piperidineN-oxide on the carboxylic acid function was used as a ligand to complex cupric ions. In aqueous solutions, blue species, of low stability, were obtained. E.p.r. spectroscopy showed the formation of various complexes. At basic pH values, a paramagnetic signal is observed with A = 101 gauss and g = 2.16. The spectroscopic parameters are interpreted in terms of strong magnetic exchange between the spin-labelled ligand and cupric ions.