Synthesis of tetrahydrobenzophenanthridinones. V

The preparation of tetrahydrobenzophenanthridinones 4 and 5 , potential useful intermediates for the synthesis of Dynemicin A models, is described. The structure of all products was corroborated by ir, ¹H-nmr, ms and X-ray spectroscopy.     

On the reactivity of μ2-acetylenes coordinated to cobalt : II. Regiospecifity of the carbonylation of internal acetylenes

The μ₂-carbonyl- μ₂-spiro(2,3-substituted-2-butene-4-olide-4-ylidene)bis(tricarbonylcobalt)(CoCo), Co₂(CO)₇(C₄O₂R¹R²), “lactone” complexes were prepared from internal acetylenes. It was found that the reaction is regiospecific; in the products from an asymmetric internal alkyne the sp carbon atom which had the higher value of the ¹³C NMR chemical shift (δ) occupied the 2-, while that with the lower δ value the 3-position of the lactone ring. fa]For Part I, see ref. 1. Some results or this work were presented at the Annual Meeting of the Hungarian Chemical Society (MKE Vegyészkonferencia), Aug. 23–26, 1977. Debrecen. Abstracts (Elöadások összefoglalói) p. 156     

Thermal stability of three amines in pressurized water reactor secondary systems. Laboratory and loop experiments

Laboratory and loop tests have been carried out in order to investigate the thermal stability of the three amines, morpholine, AMP (aminomethylpropanol) and sarcosine in PWR secondary conditions. Laboratory experiments have been performed in a titanium autoclave at 300°C. The results pointed out high thermal decomposition rates of AMP and sarcosine. A decomposition mechanism is proposed for the 3 amines. Loop tests have been performed in order to compare steam cycle conditioning with ammonia, morpholine and AMP. The amine concentrations and the decomposition products such as acetate and formate have been followed around the secondary circuit of the ORION loop which reproduces the main physico-chemical characteristics of a PWR secondary circuit. These concentrations are reported together with the evolution of cationic conductivities. The influence of oxygen concentration on amine thermal stability has been observed. Results are expressed also in terms of decomposition rates and of relative volatility.Presented at the Second International Symposium on Chemistry in High Temperature Water, Provo, UT, August 1991.     

Cis-UROCANIC ACID SYNERGIZES WITH HISTAMINE FOR INCREASED PGE2 PRODUCTION BY HUMAN KERATINOCYTES: LINK TO INDOMETHACIN-INHIBITABLE UVB-INDUCED IMMUNOSUPPRESSION

Abstract— There is considerable evidence that suppression of the immune system by UVB (280–320 nm UV) irradiation is initiated by UVB-dependent isomerization of a specific skin photoreceptor, urocanic acid (UCA), from the trans to the cis form. Previous studies have confirmed that cis -UCA administration to mice 3–5 days prior to hapten sensitization at a distant site, suppresses the contact hypersensitivity (CHS) response upon challenge. This study demonstrates in mice that cis -UCA, like UVB, suppresses CHS to trinitrochlorobenzene by a mechanism partly dependent on prostanoid production. In vitro experimentation showed that human keratinocytes, isolated from neonatal foreskin, increased prostaglandin E₂ (PGE₂) production in response to histamine but not UCA alone. However, cis -UCA synergized with histamine for increased PGE₂ production by keratinocytes. cis -urocanic acid also increased the sensitivity of keratinocytes for PGE₂ production in response to histamine. Prostaglandin E₂ from keratinocytes exposed to cis -UCA and histamine may contribute directly, or indirectly, to the regulation of CHS responses by UVB irradiation.     

Das Schwingungsspektrum des synthetischen Carnotits

The infrared and laser-Raman spectra of synthetic carnotite, K₂[(UO₂)₂V₂O₈], are reported and discussed. Force constants for the terminal V-O bonds as well as for the UO₂ ²⁺ ions are evaluated. From the spectroscopic data, a U-O bond length of 1.81 Å is estimated for the uranyl ion in this compound.

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15. Mitteilung der Reihe Orthovanadate und verwandte Verbindungen 14. Mitt:E. J. Baran, J. C. Pedregosa undP. J. Aymonino, Mh. Chem.106 1085 (1975).     

Structure of (Z)-1-p-methoxyphenyltelluro-1,4-diphenyl but-1-en-3-yne

C₂₃H₁₈TeO,M _r=437.97, ,a=9.940(2),b=13.664(3),c=7.895(2) Å, =80.60(1), =69.71(2), =75.95(1)°,V=972.0(4) ų,Z=2,R=0.041 for 2668 observed reflections. The Te–C bond distances are 2.109(5)Å and the C–Te–C angle is 96.0(2)°. The phenyl rings are planar to within experimental accuracy, making dihedral angles of 64.6(2), 65.3(2) and 31.1(3)°.     

Comparison of the simplex,marquardt, and extended and iterated extended kalman filter procedures in the estimation of parameters from voltammetric curves

The use of the simplex, Marquardt, and extended and iterated extended Kalman filter nonlinear least-squares curve-fitting methods is examined for evaluation of parameters in linear-sweep and cyclic voltammetric curves. The EE mechanism (two-electron transfer) is considered as a reference process and the relevant results are compared on the basis of accuracy, computing time and robustness. The E° values for l-β-3,4-dihydroxyphenylalanine are calculated.     

Das Schwingungsspektrum von Sr2V2O7 und die Schwingungseigenschaften des Divanadat-Ions

The infrared and laser-Raman spectra of Sr₂V₂O₇ are reported and discussed by means of a Site Symmetry analysis. The principal force constants as well as the mean amplitudes of vibration for the V₂O₇ ^4– ion have been calculated using a simplified molecular model. Some aspects of the vibrational behaviour of the V–O–V bridge in this ion are also discussed.

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22. Mitt. der Reihe Orthovanadate und verwandte Verbindungen. 21. Mitt.:M. E. Escobar undE. J. Baran, Z. Naturforsch.B32, 349 (1977); 20. Mitt.:E. J. Baran undI. L. Botto, Mh. Chem.,108, 311 (1977); 19. Mitt.:E. J. Baran, Z. anorg. allgem. Chem.427, 131 (1976).     

Enantioseparations in nonaqueous capillary liquid chromatography and capillary electrochromatography using cellulose tris(3,5-dimethylphenylcarbamate) as chiral stationary phase

The potential of the widely used chiral stationary phase for high-performance liquid chromatography (HPLC) enantioseparations, cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC, sold under the trade name Chiralcel OD) was evaluated under the conditions of nonaqueous capillary electrochromatography (CEC). The effect of the particle size of the silica gel, the loading of CDMPC on the silica gel and nature of the organic solvent, as well as electrolyte salts on the separation characteristics were investigated. This study illustrates the applicability of CDMPC for obtaining highly efficient enantioseparations under the conditions of nonaqueous CEC. Comparative study of enantioseparations in capillary liquid chromatography (CLC) and CEC indicated the significant advantages of CEC such as higher plate number at the similar linear flow rates of the mobile phase as well as better tolerance of higher linear flow rates.