A novel strategy for the preparation of naturally occurring phosphocitrate and its partially esterified derivatives

A novel method for the synthesis of phosphocitrate (1, PC) starting from triethyl ester of citric acid and MeOPCl2 is described. The method is based on selective stepwise hydrolysis of ester moieties from the intermediate Me-O-P(O)(Cl)(Z) (Z = triethylcitrate), 4a, which also allows one to prepare partially esterified derivatives of PC with good yield and purity without chromatographic purifications.     

Synthesis of new o-alkyl substituted arylalkylphosphanes: study of their molecular structure and influence on rhodium-catalyzed propene and 1-hexene hydroformylation

A set of new phosphane ligands designed to increase the branched-to-normal ratio of the hydroformylation reaction were prepared in the same way as the previously reported ortho-alkyl substituted arylphosphanes, which have shown increased i/n ratios in the hydroformylation of propene and 1-hexene. In order to determine the relationship between the catalytic behavior and stereoelectronic properties of the ligands, various functional alkyl groups (methyl, isopropyl, cyclohexyl) were placed on the phosphorus atom directly and in the ortho position of the phenyl ring connected to phosphorus. In the hydroformylation reaction of propene and 1-hexene a higher i/n ratio resulted with nearly all the ligands compared with that of triphenylphosphane. Additionally as the ortho-alkyl-substituent became larger, it had a favorable effect on the i-selectivity. Characterization of the ligands was carried out by NMR spectroscopy (mainly ¹H, ³¹P{¹H}, ¹³C{¹H}, HSQC/HETCOR and COSY-90). Properties of the ligands were also studied by quantum mechanical calculations and by synthesizing three Rh(acac)(CO)(PR₃) derivatives. The o-alkyl-substituent was orientated outside the ligands’ cone angle in the X-ray crystal structures of (2-cyclohexylphenyl)dicyclohexylphosphane and (2,5-dimethylphenyl)bis(4-pyridyl)phosphane, and Rh(acac)(CO)(PR₃) complex of (2-methylphenyl)dicyclohexylphosphane.     

Systematic study of the physicochemical properties of a homologous series of aminobisphosphonates

Aminobisphosphonates, e.g., alendronate and neridronate, are a well known class of molecules used as drugs for various bone diseases. Although these molecules have been available for decades, a detailed understanding of their most important physicochemical properties under comparable conditions is lacking. In this study, ten aminobisphosphonates, H₂N(CH₂)_nC(OH)[P(O)(OH)₂]₂, in which n = 2-5, 7-11 and 15 have been synthesized. Their aqueous solubility as a function of temperature and pH, pK_a-values, thermal stability, IR absorptions, and NMR spectral data for bothliquid (¹H, ¹³C, ³¹P-NMR) and solid state (¹³C, ¹⁵N and ³¹P-CPMAS NMR) were determined.     

Poly[(acetone)tetraaqua[μ6‐ethyl (dichloromethylene)diphosphonato][μ5‐ethyl (dichloromethylene)diphosphonato]tribarium(II)]

The novel title compound, [Ba₃(C₃H₅Cl₂O₆P₂)₂(C₃H₆O)(H₂O)₄]_n, has a polymeric two‐dimensional network structure which lies parallel to the (10) plane. The asymmetric unit consists of three independent Ba²⁺ ions, two of them eight‐coordinated and the third nine‐coordinated, and two independent ethyl (dichloromethylene)diphosphonate(3−) ligands, one acetone ligand and four aqua ligands. The coordination environments around the BaO₈ polyhedra are best described as bicapped trigonal prismatic, while the BaO₉ polyhedron is in a distorted tricapped trigonal prismatic geometry. The two diphosphonate ligands adopt different coordination modes. Both ligands chelate three metal cations, but one is coordinated to six metal cations in total and forms two six‐membered and one four‐membered chelate ring, while the other is coordinated to five metal cations in total and forms one six‐membered and two four‐membered chelate rings, the fifth unsubstituted O atom remaining uncoordinated.     

Study of low-lying collective states using a Microscopic Anharmonic Vibrator Approach

Anharmonic features of the low-lying collective states in the ruthenium isotopes have been investigated systematically by using the Microscopic Anharmonic Vibrator Approach (MAVA). MAVA is based on a realistic microscopic G-matrix Hamiltonian, only slightly renormalized in the adopted large realistic single-particle spaces. This Hamiltonian is used to derive equations of motion for the mixing of one-and two-phonon degrees of freedom starting from collective phonons of the quasiparticle random-phase approximation. Interesting applications to analysis of double-beta-decay rates to excited collective states are foreseen. Presented by J. Suhonen at the Workshop on calculation of double-beta-decay matrix elements (MEDEX’05), Corfu, Greece, September 26–29, 2005.     

Determination of novel complexing agents in pulp and paper mill effluents and in lake water by liquid chromatography

A simple and sensitive high performance liquid chromatographic (HPLC) method with UV detection was developed for the determination of new diethanolamine derivative complexing agents. The quantitation of three complexing agents was accomplished as their Cu(II) complexes and their separation on a reversed phase C18 column using 0.01 M tetrabutyl ammoniumhydroxide and methanol as isocratic mobile phase. The limit of detection (LOD) ranges from 0.1 to 2.0 mg/l and the method has a wide linear range, from LOD to 150 mg/l. The method was successfully applied for the analysis of lake water and wastewater effluent from pulp and paper mill spiked with studied complexing agents.     

Environmental water monitoring by capillary electrophoresis and result comparison with solvent chemistry techniques

The aim of this work was to determine inorganic ions from natural waters by capillary electrophoresis (CE) and to compare the results obtained with those measured with conventional solvent chemistry techniques. The project was part of a larger CE study, during which we measured inorganic ions from some lake and river systems and groundwaters in Southern Finland. Results obtained from contaminated Finnish waters were compared with samples from the River Rhine in the Düsseldorf area. Two CE methods were used for analysis: one for determination of chloride, sulfate, nitrite and nitrate at pH 7.7 and the other for ammonium, potassium, calcium, sodium and magnesium at pH 3.6, both methods using identification based on indirect UV detection. Two separation methods were used in order to prevent complex formation of metals with sulfate, hydroxide and decomposed organic matter present in the environmental samples. On the basis of the CE studies dilution was needed for those samples having more than 100 mg/l of sulfate, chloride, calcium and sodium. On average, the natural waters in the study contained ammonium, magnesium, sodium, potassium and calcium below 0.3, 20, 200, 20, and 200 mg/l, respectively. The concentrations of chloride, sulfate, nitrite and nitrate were below 20, 100, 10, and 10 mg/l, respectively. Correlation of the CE results with those acquired by titration, atomic absorption spectrometry, ion chromatography and flow injection analysis were obtained; R2 values for the comparison tests varied from 0.8816 to 0.9994 depending on the ion. The repeatabilities of the anion and cation CE methods were tested using laboratory-made reference sample mixtures with high and low salt concentration.