Studies on 4-Pyrones and 4-Pyridones. III. The Preparation of Some New 5-Hydroxy-1-aryl-4-pyridone-2-carboxylic Acids and Related Compounds

By condensation of meconic acid with 4-chloroaniline, 4-bromoaniline, 3-nitroaniline and 1-naphthylamine, hitherto und esc ribed 5-hydroxy-1-a,ryl-4-piridone-2-carboxylic acids (I-IV) h ave been prepared. D ecarboxylation of the acids yielded several new 5-hydroxy- 1-aryl-4-pyridones (V-VII). Esterification of I-IV, as well as of two earlier reported analogous acids\u27 led to the for m ation of the corresponding esters (VIII-XIV) in good yield

5-Hydroxy-1-aryl-4-pyridone-2-carboxylic Acid Esters as Chelating and Extracting Agents. I. Extraction and Separation of Tantalum(V) and Niobium(V) from Oxalate Solutions

The extraction of niobium and tantalum from oxalate solution has been studied using the esters of 5-hydroxy-l-aryl-4-pyridone- 2-carboxylic acid as extractants. The influence of the concentration of hydrochloric, sulphuric, hydrofluoric and oxalic acids on the extraction of niobium and tantalum has been investigated. The dependence of the extraction of these metals upon the concentration of the extractant in the organic phase was also studied. A procedure for the separation of niobium from tantalum directly from oxalate solution is described. The radionuclides 95Nb and 182Ta were used for the determination of the distribution coefficients

5-Hydroxy-1-aryl-4-pyridone-2-carboxylic Acid Esters as Chelating and Extracting Agents. I. Extraction and Separation of Tantalum(V) and Niobium(V) from Oxalate Solutions

The extraction of niobium and tantalum from oxalate solution has been studied using the esters of 5-hydroxy-l-aryl-4-pyridone- 2-carboxylic acid as extractants. The influence of the concentration of hydrochloric, sulphuric, hydrofluoric and oxalic acids on the extraction of niobium and tantalum has been investigated. The dependence of the extraction of these metals upon the concentration of the extractant in the organic phase was also studied. A procedure for the separation of niobium from tantalum directly from oxalate solution is described. The radionuclides 95Nb and 182Ta were used for the determination of the distribution coefficients

A Discussion of the Absorption Spectra of Substituted 4-Pyridones and Their 4-Thio Analogues

The absorption spectra of 3-hydroxy-1-aryl-4-pyridones, 2-carbethoxy- 5-hydroxy-1-aryl-4-pyridones and their 4-thio analogues are reported . The thio compounds exhibit a red shift in the characteristic long wavelength maximum, which can be explained with the help of the inductive effect when oxygen is replaced by sulphur. Similarly, with the help of the first-order inductive effect, a red shift in the bands is discussed . This shift is produced by the substitution of a carbethoxy group at position 2 of the pyridone ring (the charge distributions in the ring are calculated from Hilckel molecular orbitals). Finally, a red shift produced by substitution onto the nitrogen in the ring is examined with the help of the mesomeric effect

Zur Kenntnis der 2-(2\u27-Furyl)-benzthiazole. Thioamide. V. Mitteilung

Es wird eine Reihe neuer, im Benzolkern substituierter 2-(2\u27- Furyl)-benzthiazole, die durch Oxydation der entsprechenden Thiobrenzschleimsaure-N-arylamide mit Kaliumferricyanid in guter Ausbeute gewonnen werden konnten, beschrieben. Fur Identifikationszwecke wurden die gut kristallisierenden Pikrate von 2-(2\u27-Furyl)-benzthiazol und seinen in vorliegender Arbeit beschriebenen Abkommlingen dargestellt

Experimental discrimination of ion stopping models near the Bragg peak in highly ionized matter

The energy deposition of ions in dense plasmas is a key process in inertial confinement fusion that determines the α-particle heating expected to trigger a burn wave in the hydrogen pellet and resulting in high thermonuclear gain. However, measurements of ion stopping in plasmas are scarce and mostly restricted to high ion velocities where theory agrees with the data. Here, we report experimental data at low projectile velocities near the Bragg peak, where the stopping force reaches its maximum. This parameter range features the largest theoretical uncertainties and conclusive data are missing until today. The precision of our measurements, combined with a reliable knowledge of the plasma parameters, allows to disprove several standard models for the stopping power for beam velocities typically encountered in inertial fusion. On the other hand, our data support theories that include a detailed treatment of strong ion-electron collisions

A Discussion of the Absorption Spectra of Substituted 4-Pyridones and Their 4-Thio Analogues

The absorption spectra of 3-hydroxy-1-aryl-4-pyridones, 2-carbethoxy- 5-hydroxy-1-aryl-4-pyridones and their 4-thio analogues are reported . The thio compounds exhibit a red shift in the characteristic long wavelength maximum, which can be explained with the help of the inductive effect when oxygen is replaced by sulphur. Similarly, with the help of the first-order inductive effect, a red shift in the bands is discussed . This shift is produced by the substitution of a carbethoxy group at position 2 of the pyridone ring (the charge distributions in the ring are calculated from Hilckel molecular orbitals). Finally, a red shift produced by substitution onto the nitrogen in the ring is examined with the help of the mesomeric effect