The solvent extraction of Cu(II), Ni(II), and Co(II) with diacetyl-mono-(2-quinolylhydrazone)

Summary A semi-automatic microliter sample injector with an 8-way motor-driven rotary valve was constructed for a conventional pneumatic nebulizer. After a 40-l sample was injected into an injection tee with a micro-syringe, nebulization and flushing the sample pathway with water followed by argon were automatically executed. An automatic peak detector/integrator was employed in each channel of a three-channel spectrometer for simultaneous multielement analysis. The relative standard deviation of the peak height for 1g Zr/ml was 1.7% and measuring time of one sample was about 1 min. Detection limits were 2 to 6 times higher than those in continuous feeding.

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Halbautomatische Injektion von Mikroliter-Proben in ein induktiv gekoppeltes Plasma zwecks simultaner Multielementanalyse

Zusammenfassung Ein halbautomatischer Injektor für Mikroliterproben mit einem motorgetriebenen 8-Weg-Ventil für ein konventionelles Vernebelungsgerät wurde konstruiert. Nachdem eine 40-l-Probe mit einer Mikroinjektionsspritze in ein Injektions-T-Stück eingeführt ist, erfolgt automatisch Vernebelung, dann Spülung des Probenweges zunächst mit Wasser, dann mit Argon. Ein automatischer Spitzen-Detektor/Integrator in jedem der drei Kanäle des Spektrometers ermöglicht die gleichzeitige Multielementanalyse. Die rel. Standardabweichung der Spitzenhöhe für 1g Zr/ml betrug 1,7%, die Zeit für die Messung einer Probe ungefähr eine Minute. Die Nachweisgrenzen sind 2- bis 6mal höher als bei kontinuierlicher Zugabe.

     

Diacetyl-bis-(2-pyridyl)hydrazone as an extracting agent for Cu(II), Co(II), and Ni(II)

Summary DbPH, a quadridentate chelating agent, was studied as a solvent extraction reagent for Cu(II), Co(II), and Ni(II). In all cases 11 complexes were extracted; however for Cu(II) and Co(II) ion-paired species exist, while for Ni(II) only neutral complexes were extracted. In all cases an extraction efficiency of 35–60% was observed unlike the greater than 90% observed for similar mono-hydrazone derivatives. The steric hindrance probably present in the bis adduct prevented a more efficient extraction.

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Diacetyl-bis-(2-pyridyl)hydrazon (DbPH) als Extraktionsmittel für Cu(ll), Co(II) und Ni(II)

Zusammenfassung DbPH bildet mit Cu(II), Co(II) und Ni(II) Komplexverbindungen im Verhältnis 11; diese sind für Cu und Co ionisierbar, im Falle des Ni läßt sich ein neutraler Komplex extrahieren. Die Extraktion erreicht jedenfalls nur 35–60% im Gegensatz zu mehr als 90% bei ähnlich gebauten Monohydrazon-Derivaten. Sterische Hinderung dürfte hierfür die Ursache sein.

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Presented at the 18th Middle Atlantic Regional Meeting of the American Chemical Society, Newark, New Jersey, May 21, 1984.     

Matrix-isolation-FTIR spectroscopy with an integrating sphere

The use of an integrating sphere for the measurement of absorption spectra of thin films is described. The thin film (for example a rare gas matrix) is grown directly on the inside surface of the sphere. Multiple reflections inside the integrating sphere lead to significant enhancement of weak absorptions of the film, increasing the sensitivity of such measurements.     

Amide interactions in chlorinated solvents

Enthalpies of solution and of transfer of amides for the solvents chloroform (CHCl₃), methylenechloride (CH₂Cl₂), carbontetrachloride (CCl₄), cyclohexane (C₆H₁₂), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), and ethylacetate (EtOAc) have been used to isolate and quantify the solvation interactions of amides in chlorinated solvents. Specific interactions at the aminde carbonyl and N–H groups have been identified. An analysis of the transfer enthalpies of pyrrole and methylpyrrole from cyclohexane to the chlorinated solvents shows that specific interactions between the pyrroles and these solvents are similar in nature. A means of calculating differences in the transfers of different solutes between the same solvent pair is given.Work done at Lebanon Valley College.     

SCF perturbation theory for unimolecular reactions

A CNDO/2 SCF perturbation theory is presented for interpreting the form of CNDO/2 potential energy surfaces of unimolecular reactions. The analysis is performed by calculating the energy change E arising from a distortion of the molecular geometry along the reaction coordinate. E is decomposed into different perturbational contributions which are appropriate for an interpretation of the perturbation energy E. Moreover, E is resolved into energy parts arising from a single occupied orbital and contributions due to pairwise orbital interactions. In this way one evaluates numerically how the form of the occupied and unoccupied orbitals determines the magnitude of E. If the distortion occurs along a definite symmetry coordinate, group-theoretical arguments can be applied to discuss the magnitude of characteristic components of the perturbation energy. The SCF perturbation theory is used to analyze the isomerization of ethylene, cis-2-butene and cis-2-butenenitrile.This work was partially supported by Nato-Grant No. 1072     

Nonlinear desingularization in certain free-boundary problems

We consider a nonlinear, elliptic, free-boundary problem involving an initially unknown setA that represents, for example, the cross-section of a steady vortex ring or of a confined plasma in equilibrium. The solutions are characterized by a variational principle which allows us to describe their behaviour under a limiting process such that the diameter ofA tends to zero, while the solutions degenerate to the solution of a related linear problem. This limiting solution is the sum of the Green function of the linear operator and of a smooth function satisfying the boundary conditions. Mathematically speaking, this limiting process, that we call nonlinear desingularization, is a novel kind of bifurcation phenomenon since the nonlinear effect here involves smoothing the singularity of the associated linear problem.Research partially supported by A FOSR and NSF grants     

Organometallic complex compounds,part 6(1). Property-specific ligand control of stability and reactivity of (1,3-dimethyl-η3-allyl)methylnickel-ligand complexes. Separation of electronic and steric effects

Summary The property-specific ligand control of 28 ligands on the decomposition temperatures in solution, measured by d.t.a. of a four-coordinate nickel(II)-complex is reported. A quantitative separation of electronic and steric effects by a multilinear regression analysis (75% electronic and 25% steric influence for the chosen ligands) is presented. The controlling effect of the selectivity on the decomposition (fraction of the C-C-linked product) (25 P-ligands) leads to an electronic: steric ratio of the property-specific ligand control of 5545 for the chosen ligands. An increase in the relative acceptor character of the P-ligands relatively destabilizes the complexes and thereby favours formation of a C-C-bond. An increase in steric hindrance also favours C-C-bond formation. A method for revising the steric parameter of P-ligands is presented and is used to correct the -value of (PhCH₂)₃P is corrected to 135°. SCCC-MO-calculations for testing the chemical reasoning of the separated electronic and steric ligand property control are shown.