Electrochemical fluorination of chlorine-containing amines

The electrochemical fluorination of chlorine-containing alkylamines has been studied. It was found that, in general, the carbon-chlorine bond in the alkylamines is retained during electrochemical fluorination is anhydrous hydrogen fluoride, yielding chlorine-containing polyfluoroalkylamines. Perfluoroalkylamines and fluorocarbons were also produced.By the use of this method, several new chloropolyfluoroamines such as (CF₃)₂NCF₂CClF₂, (C₂F₅)₂NCF₂CClF₂, (CF₃)(C₂F₅)NCF₂CClF₂, (CClF₂CF₂)₂NCF₃, (CClF₂CF₂)₂NC₂F₅, (C₂F₅)(CClF₂CF₂)NF, (CClF₂CF₂)₂NF, (CF₃)₂NCF₂CF₂CClF₂, $\text{CF}{}_2\text{(CF}{}_2\text{)}{}_3\text{N}$CF₂CClF₂, and $\text{CF}{}_2\text{CF}{}_2\text{OC}{}_2\text{F}{}_4\text{N}$CF₂CClF₂ have been isolated and characterized.     

Solid Phase Extractive Preconcentration of Cobalt and Nickel in Hair Samples Using Ethyl Xanthate Modified Benzophenone

The ethyl xanthate complexes of cobalt and nickel are quantitatively retained on benzophenone in the pH range of 8.0–10.0. The solid mixture consisting of metal complex together with benzophenone is dissolved in 5mL of dimethyl formamide, and the cobalt and nickel contents were determined by flame atomic absorption spectrometry. The calibration graphs are rectilinear over the concentration range of 0–75 (Co) and 0–100 (Ni) µgL^–1. The detection limits of flame AAS for cobalt and nickel are lowered by a factor of 200 due to the solid phase extraction preconcentration procedure. NIES CRM Human Hair No. 5 and IAEA Reference Hair HH-1 certified reference materials were used in order to verify the accuracy of the developed preconcentration method in analysing human hair samples. The results obtained were found to be in excellent agreement with certified values. Furthermore, hair samples collected from various inhabitants of different age groups and sex living in the Indian states of Andhra Pradesh and Tamil Nadu were successfully analysed by flame AAS in conjunction with the solid phase extraction preconcentration procedure developed for cobalt and nickel.     

Polymerization of coordinated monomers. XXI. Ab initio molecular orbital study on the binary molecular complex composed of methyl methacrylate and boron trifluoride

The stereo- and electronic structures of the binary molecular complex composed of methyl methacrylate and boron trifluoride are obtained by using an ab initio molecular orbital method with an STO-3G basis set. The total energy change on the binary molecular complex formation is ?1.3 X 10^?2 Hartree (?8.2 kcal/mol). The electron transfer from methyl methacrylate to boron trifluoride and the change in the energy level of the lowest unoccupied molecular orbital of methyl methacrylate on the complex formation with boron trifluoride are much smaller than those on the complex formation with boron trichloride. A twisted form in which the dihedral angle between the vinyl plane and the ester plane is 16.9° is the most stable structure of the binary molecular complex composed of methyl methacrylate and boron trifluoride. A strong bonding overlap population between a β-hydrogen of methyl methacrylate and a fluorine of boron trifluoride is found in this conformation. © 1992 John Wiley & Sons, Inc.     

Rhodium Fluoroapatite Catalyzed Conjugate Addition of Arylboronic Acids to α,β‐Unsaturated Carbonyl Compounds

Rhodium fluoroapatite (RhFAP) is an efficient catalyst for conjugate addition of organoboron reagents to α,β‐unsaturated carbonyl compounds. A variety of arylboronic acids and α,β‐unsaturated carbonyl compounds were converted to the corresponding conjugate‐addition products, demonstrating the versatility of the reaction. The reaction is highly selective. RhFAP was recovered quantitatively by simple filtration, and reused for four cycles.     

Instanton counting on blowup. I. 4-dimensional pure gauge theory

We give a mathematically rigorous proof of Nekrasov’s conjecture: the integration in the equivariant cohomology over the moduli spaces of instantons on ℝ⁴ gives a deformation of the Seiberg-Witten prepotential for N=2 SUSY Yang-Mills theory. Through a study of moduli spaces on the blowup of ℝ⁴, we derive a differential equation for the Nekrasov’s partition function. It is a deformation of the equation for the Seiberg-Witten prepotential, found by Losev et al., and further studied by Gorsky et al. Mathematics Subject Classification (2000) 14D21, 57R57, 81T13, 81T60     

Blei

Ohne Zusammenfassung     

Geometric shapes withg- bosons in the interacting boson model

Geometric aspects of the extended interacting boson model (gIBM) withs, d andg bosons are studied using coherent states. Algebraic expressions for the coherent state expectation values of various terms in the general gIBM Hamiltonian are derived in terms of the quadrupole and hexadecupole deformation variablesβ ₂ andβ ₄ and the asymmetry angleγ. These in turn are used to determine the equilibrium shape parameters (β ₂ ⁰ ,β ₄ ⁰ ,γ ⁰) in the seven dynamical symmetry limits of gIBM.     

Gold‐Catalyzed Enantioselective Synthesis,Crystal Structure,and Photophysical/Chiroptical Properties of Aza[10]helicenes

The enantioselective synthesis of an aza[10]helicene, possessing two pyridone units, has been achieved by the gold‐catalyzed intramolecular quadruple hydroarylation of a tetrayne. This aza[10]helicene was successfully converted into a fully aromatic aza[10]helicene, possessing two pyridine units. Structure–photophysical and chiroptical properties relationship in a series of azahelicene isomers has also been disclosed.