HPLC of aminoacids on silica coated with ammonium tungstophosphate

Summary The chromatographic behaviour of aminoacids on columns of silica coated with different percentages of ammonium tungstophosphate at several buffer phosphate concentrations is reported. The stationary phase shows a high selectivity towards aminobutyric acids and methyl derivatives of tryptophan due to the distance between the carboxylic group and the –NH ₃ ⁺ group involved in the cation-exchange process and/or to the steric hindrance by a methyl substituent. A relationship between HPLC and HPTLC data has been verified and applied to the prediction of the separation of six aminoacids.     

K11[HSn(PWO34)2] · 27 H2O – Synthese und Struktur

K₁₁[HSn (PW O₃₄)₂] · 27 H₂O – Synthesis and Structure K₁₁[HSn (PWO₃₄)₂] · 27 H₂O 1 can be synthesized in an “one-pot reaction” from commercially obtainable educts (SnCl₂; Na₂HPO₄ · 7 H₂O, Na₂WO₄ · 2 H₂O) in high yields and has been characterized by elemental analysis, IR/Raman-, UV/Vis-spectroscopy as well as by X-ray crystal structure analysis. The example of 1 again demonstrates the validity of our working hypothesis, that polyoxometalates can be obtained by linking highly charged, transferable building blocks by cationic centres within the scope of an optimal charge control. For structural details see “Inhaltsübersicht”.     

Oxidation of Long Chain Primary Alcohols to Acids over the Quaternary Ammonium Peroxotungstophosphate Catalyst System

Factors influencing the catalytic properties for long chain primary alcohol oxidation to acid over quaternary ammonium peroxotungstophosphate catalyst were investigated. The catalysts were characterized by means of IR and NMR techniques. Based on the experimental results, the catalyst active centers for the title reaction were elucidated and optimal reaction conditions given.