5-Hydroxy-2-pyrazolines and Some of Their 1-Substituted Analogs

The use of 1,3-dicarbonyl compounds containing strong electron-withdrawing substituents (perfluoroalkyl, 4-nitrophenyl) at one of the carbonyl groups in reaction with hydrazine or its monosubstituted derivatives (4-nitro- and 2,4-dinitrophenylhydrazines) leads to the formation of stable intermediates for the synthesis of pyrazoles (5-hydroxy-2-pyrazolines) or their linear tautomers (hydrazones).     

Efficient laser operation and continuous-wave diode pumping of Cr2+:ZnSe single crystals

Efficient continuous-wave laser operation of Cr²⁺:ZnSe was demonstrated with an output power of 1400 mW at an absorbed pump power of 1900 mW from a Tm:YAG laser. Under continuous-wave diode pumping at 1.54 μm an output power of 15 mW was obtained from a Cr⁺²:ZnSe laser. Excited state absorption is shown to be negligible in the pump and laser spectral region. Received: 12 October 2000 / Published online: 30 November 2000     

Reaction of trifluoromethyl-containing 1,3-dicarbonyl compounds with bis-hydrazides

Carbonic dihydrazide reacted with 2 equiv of trifluoroacetylacetone to give a compound containing 5-hydroxy-4,5-dihydropyrazole and keto enehydrazine fragments. Analogous 2 : 1 condensations of trifluoro-acetylacetone and 4-ethoxy-1,1,1-trifluorobut-3-en-2-one with oxalohydrazide and malonohydrazide afforded bis(5-hydroxy-4,5-dihydropyrazole) structures as two diastereoisomers.     

Azeotropic phenomena in a dilute solution of lithium hydride in lithium at liquid-vapor phase equilibrium

A Li-LiH-type system under liquid-vapor phase equilibrium conditions was considered. Liquid is a binary infinitely dilute solution of lithium hydride in lithium, and the coexisting vapor phase is a multi-component chemically reacting ideal mixture of gas components. The phenomenon of the existence of azeotropy in such systems, earlier unknown, was established. The concentration of the components was expressed in the atomic fractions of hydrogen in both phases. The temperature and concentration boundaries of the azeotropic zone were found. The trends revealed are of importance for applications.     

Ring-chain tautomerism of 2-mercaptobenzoylhydrazones of aromatic aldehydes

It has been shown by ¹H NMR spectroscopy that 2-mercaptobenzoylhydrazones of aromatic aldehydes 2-HSC₆H₄CONHN=CHC₆H₄X (X = 4-NO₂, 3-NO₂, 4-Br, H, 4-Me, 4-MeO, 4-Me₂N) exist in DMSO-d₆ solution as tautomeric mixtures of linear and cyclic benzo-1,3,4-thiadiazepine forms. The linear hydrazone form is represented by (E,Z′)-conformational isomers, differing in the disposition relative to the amide C–N bond. It was shown that the logarithm of the tautomeric equilibrium constant K _T correlates with the σ-constants of the substituents in the aromatic nucleus.     

Quantitation of Si,B, Ca,Mg, Ba,and Zr in Complex-Alloyed Nickel Alloys by ICP-MS

The possibility of the use of a collision and reaction cell is shown and the optimum parameters for its adjustment are selected for the determination of Si, B, Ca, Mg, Ba, and Zr in a complex-alloyed nickel alloy via inductively coupled plasma mass spectrometry (ICP-MS). The procedure of sample dissolution and its preparation for the analysis is presented. The correctness of the obtained results is confirmed by the analysis of the certified reference standard of a nickel alloy.     

Accurate method for the measurement of absorption cross sections of solid-state saturable absorbers

A rigorous approach taking into account both the temporal and spatial distributions of the pulsed probe beam used for transmission measurements of solid-state saturable absorbers is applied to characterise these absorbers accurately. The use of this method can significantly influence the resulting value for the ground-state absorption cross section. It also permits us to avoid the introduction of an artificial excited-state absorption in systems where, according to energy-level diagrams, no such loss should occur. This is illustrated in the case of passive Q-switchers for 1.5-μm lasers such as Co²⁺-doped LaMgAl₁₁O₁₉ and MgAl₂O₄ and Co²⁺- or Cr²⁺-doped ZnSe and ZnS. Received: 21 November 2001 / Revised version: 22 January 2002 / Published online: 14 March 2002