Dissociation behavior of poly(α‐hydroxy acrylic acid)

Dissociation behavior of poly(α‐hydroxy acrylic acid) (PHA) was investigated by potentiometric titration in the presence of NaCl and/or divalent metal chlorides. It was found that pH values of PHA aqueous solutions increased with time when the degree of dissociation, α, is high (α ≧ 0.5 for NaCl system) and decreased in the lower α region (α < 0.5 for NaCl). The increase of pH was attributed to lactone ring formation that occurs between a carboxyl group and a neighbor hydroxyl group upon protonation to the former, and the decrease of pH to an induction effect by lactone ring to −COOH group. The pH‐increasing process was analyzed by assuming it being of a first order to obtain a time constant. On the basis of time constant thus estimated and pKa values for divalent counterion systems, a correlation between counterion binding and lactone ring formation was discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1523–1531, 1999     

Regioselective synthesis of virazole using benzyl cyanoformate as a synthon

An antiviral nucleoside or virazole was synthesized efficiently and regioselectively starting with benzyl cyanoformate.     

Ueber die Beziehungen von Neutralsalz zu Säureeiweiß

Ohne Zusammenfassung     

Jellium-model calculation for monomer and dimer decays of some potassium clusters

We have studied several decay processes of potassium clusters and found that a dimer-decay mechanism can explain the observed lowest abundance of K₁₀ in the K _n mass spectra. Total-energy curves for decay processes are calculated using a jellium-background model for positive-ion cores and the local-spin-density-functional approximation for valence electrons. The energy-barrier height for a dimer decay of K₁₀ from the energy-minimum point is found to be 0.18 eV, which is a reasonable magnitude for the decay to take place thermally in the experiment. The monomer decay of K₉ and the dimer decay of K₁₁, which are expected to be the most favorable decays of K₉ and K₁₁, are found to have high barriers. Monomer and dimer decays of K₈ are also studied and the monomer decay is found to be more favorable, in accord with the high-nozzle-temperature mass spectrum.