Einfache,regiospezifische synthese von cycloalkenonen aus lactonen

The reaction of lithiumalkylphosphonates with γ or δ-lactones followed by oxidation leads to 2,5- or 2,6-dioxophosphonates, which can be cyclized to cyclopentenones or cyclohexenones, respectively, constituting an easy, regiospecific route to cycloalkenones from lactones.     

Zur Analytik von Harnstoff-Melamin-Formaldehyd-Harzen

Summary A method is described for the distinction between urea-formaldehyde and melamine-formaldehyde resins by precipitating the melamine derivates with picric acid. The analysis of this precipitation by urease-decomposition gives information whether urea and melamine are condensed with formaldehyde together or whether the investigated resin is only a mixture of an urea-formaldehyde and a melamine-formaldehyde resin.Moreover, it is possible to prove the formation of cocondensates of urea, melamine, and formaldehyde during the three-component condensation by combination of these two methods.     

Chemical and morphological consequences of acidification of pure, phosphated, and phosphonated CaO: influence of CO2 adsorption

In situ Fourier transform infrared (FTIR) spectroscopy was employed to characterize the adsorption behavior (as a function of pressure or time) and surface species of CO2 molecules on pure, phosphated, and phosphonated CaO. Carbonate and bicarbonate species were found to form on the pure oxide, whereas on the phosphated and phosphonated oxide samples the carbonate species were found to substitute favorably some of the OH(-) and PO4(3-) groups thereon exposed, respectively. Before and after carbonation, the test samples were further examined by in situ FTIR spectroscopy of adsorbed pyridine species, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Then they were in situ acidified by exposure to a wet atmosphere of HCl vapor at 673 K for 10 min and re-examined similarly to reveal the influence of CO2 adsorption on the chemical and morphological consequences of acidification. The results obtained show the carbonate substitution of PO4(3-) groups to enhance agglomeration of the otherwise fine, longitudinal material particles into much bulkier ones and to render the otherwise more stable phosphonate groups less stable to acid treatment than the phosphate groups. Moreover, the bulky particle agglomerates of the carbonated test samples were detectably eroded following the acid treatment.