Darstellung,chiroptische eigenschaften und absolute Konfiguration von 4,14-disubstituierten [2.2]Metacyclophanen

Resolution of [2.2]metacyclophane-4,14-dicarboxylic acid (2) was achieved by crystallization of its (+)- and (–)--phenylethylamine salts. Chemical correlation with (–)-(S)_p-[2.2]metacyclophane-4-caboxylic acid (–)-11 via its monobromo derivative (–)-8 established the absolute configuration of the dicarboxylic acid as (–)-(S)_p-2. The key compound (–)-8 was prepared by partial lithiation and subsequent carboxylation of 4,14-dibromo[2.2]metacyclophane (1) and resolution with (–)-phenylethylamine.Recently proposed rules correlating the absolute configurations of planarchiral compounds with theirCD-spectra are discussed and a comparison of the chiroptical properties of 4,14-di- and 4-mono-substituted [2.2]metacyclophanes is presented.

---

---

6. Mitt.:C. Glotzmann, E. Langer, H. Lehner undK. Schlögl, Mh. Chem.106, 763 (1975).     

Extraction of cloransulam-methyl from soil with subcritical water and supercritical CO2

Cloransulam-methyl was extracted from soil samples with supercritical CO2, subcritical water and conventional organic solvents. Supercritical CO2 was less efficient than conventional organic solvents; polarity modifiers had no impact on extraction efficiency. Extraction with supercritical CO2 exhibited a strong temperature dependence. Water was as effective as strong organic solvents for the extraction of cloransulam-methyl; however cloransulam-methyl hydrolyzed when extracted at 150 degrees C. Extraction temperature was the most important variable in increasing the efficiency and rate of extraction, while extraction pressure was not a significant variable.     

Problems of using dynamic NMR techniques in studies of photoinduced molecular dynamics

Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 4, pp. 753–756, July–August, 1995.     

Rapid extraction and analysis of organic compounds from solid samples using coupled supercritical fluid extraction/gas chromatography

Summary Direct coupling of supercritical fluid extractions with gas chromatography (SFE-GC) allows the extraction, concentration, and gas chromatographic analysis of organic analytes from solid samples to be performed in less than 1 h. Coupling of the supercritical fluid extraction step with a capillary gas chromatographic column is achieved using a standard on-column injector and requires no modification of the gas chromatograph. Maximum sensitivity is achieved and analyte degradation or loss is minimized since the extracted species are quantitatively transferred into the fusedsilica capillary gas chromatographic column where they are cryogenically focused prior to normal gas chromatographic analysis using flame ionization (SFE-GC/FID) or mass spectral (SFE-GC/MS) detection. SFE-GC analysis yields good chromatographic peak shapes that compare favorably with those obtained using standard on-column injection techniques. Class-selective extractions can be achieved by performing multiple SFE-GC analyses with different extraction pressures. The ability of coupled SFE-GC to yield rapid extraction and analysis of organic analytes is demonstrated for a variety of samples including polycyclic aromatic hydrocarbons (PAHs) from treated wood, urban dust, and river sediment, phenolic species from wood smoke particulates, nicotine from tobacco, biological markers from coal, and flavor components from food products.

---

Schnelle Extraktion und Analyse von organischen Verbindungen aus festen Proben durch Kopplung von Extraktion mit überkritischen fluiden Phasen und GC

     

Renormalization and blow up for charge one equivariant critical wave maps

We prove the existence of equivariant finite time blow-up solutions for the wave map problem from ℝ²⁺¹→S ² of the form where u is the polar angle on the sphere, is the ground state harmonic map, λ(t)=t ^-1-ν, and is a radiative error with local energy going to zero as t→0. The number can be prescribed arbitrarily. This is accomplished by first “renormalizing” the blow-up profile, followed by a perturbative analysis. Mathematics Subject Classification (1991) 35L05, 35Q75, 35P25     

Application of the imaginary time step method to the solution of the static Hartree-Fock problem

A method of solution of the static Hartree-Fock problem is proposed. The method, based upon the extension of the method of solution of the time-dependent Hartree-Fock problem to imaginary time, promises to be more efficient, and applicable to more complex systems than previously proposed numerical methods.