Chemistry of heteroanalogs of isoflavones

Condensation of 2-pyridylacetonitrile with polyphenols gave the corresponding -(2-pyridyl)-acetophenones, which were converted to the pyridine analogs of natural isoflavones and to 3-pyridylchromones with methyl, trifluoromethyl, and ethoxycarbonyl groups in the 2 position. The antimicrobial activity of 3-pyridylchromones and their reaction with alkylating and acylating agents and phosphorus pentasulfide were investigated.See [1] for communication V.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1180–1185, September, 1977.     

Thermally induced ortho-metalation of dicarbomethoxyacetylenebis(triphenylphosphine)platinum

Heating a toluene solution of dicarhomethoxyacetylenebis(triphenylphosphine)platinum(0) at 130°C gives the ortho-metalated complex (Ph₃P)(Ph₂$\text{PC}{}_6\text{H}{}_4\text{)P}$t-trans-(COOMe)CCHCOOMe.     

Conformational effects in 3-halotetrahydropyrans

The conformational equilibria of 3-chloro- and 3-bromotetrahydropyran were measured by NMR and IR spectroscopy using model 2-alkyl-5-halotetrahydropyrans. The 3-chloro compound was 76·2% equatorial in carbon tetrachloride and 58·5% in acetonitrile and the 3-bromo compound 85% equatorial in carbon tetrachloride. The conformational equilibrium is discussed in terms of dipole, electronic and van der Waals effects.     

Les reactions de transposition photochimique en serie heterocyclique—IV: Photo-isomerisation des phenyl-methyl thiazoles et isothiazoles isomeres

The photochemical behaviour of twelve phenylmethylthiazole isomers is identical to that of non-methylated products. Thus, in order of decreasing reactivity we have: 2-phenylthiazole or 5-phenylisothiazole > 5-phenylthiazole or 3-phenylisothiazole > 4-phenylthiazole or 4-phenylisothiazole. The two latter undergo photoisomerization only to a slight extent.Most of the rearranged compounds (95%) are formed either by a valence bond isomerization mechanism via bicyclic intermediates where the phenyl group is conjugated to the cycle, or by the Kellogg mechanism, through a 180° rotation around the bonds adjacent to the sulphur atom.These results have furthermore allowed us to confirm the selective action of iodine in these isomerization reactions.     

Calculation of molecular geometries by SCF perturbation theory

An SCF perturbation method for investigating the effects of an arbitrary change in nuclear configuration on the electronic structure of a molecule is reported. Illustrative calculations for CO₂ and CH₃OH are presented. It is found that, when taken to second order, the error in the calculated change in energy which results from a change in nuclear configuration is typically in the range of 0.1 to 7%.     

Esr spectra and magnetic constants of α-Al2O3:Co,H

ESR spectra of the defect α-Al₂O₃:Co²⁺, H⁺ are reported and used to derive the magnetic tensors g and A. This defect is shown to exist in several types, and models in the framework of the α-Al₂O₃ structures are proposed.     

Polymerization studies on allylic compounds. III. α(substituted methyl)styrenes

The free-radical polymerization of a series of α-(substituted methyl)styrenes was investigated. These compounds were found to be inactive in homopolymerizations but copolymerized with methyl methacrylate and styrene with a retarding effect. Copolymerization characteristics were followed by rate and viscosity measurements.     

Crystalline calmagite and a study of sulphonation effects on azo dye metal-ion indicators

Calmagite was introduced in 1960 as a stable substitute for Eriochrome Black T in EDTA titrations of calcium plus magnesium. The colour changes were the same but somewhat sharper. Indicator stock solutions were stable indefinitely. The new indicator was designed as an indicator and not as a wool dye. Azo dye impurities which may be present in some commercial supplies tend to lengthen the end-points. A simple means of removing these impurities to yield crystalline indicator has been developed. The effects of sulphonation on the performance of azo dyes as indicators have been studied.     

Über die Michael-Reaktion mit Chinolacetaten, 3. Mitt.

Zusammenfassung Versuche, von o-Benzochinolacetaten ausgehend die hydroaromatischen (primären) Additionsprodukte derMichael-Reaktion zu erhalten, hatten bisher nur bei Ia und Ib mit Malonsäuredinitril Erfolg. Mit p-Benzochinolacetat VI gelingt die Darstellung der primären Additionsprodukte auch mit anderen Reaktionskomponenten, wie z. B. Malonsäurediäthylester. *** DIRECT SUPPORT *** A3615076 00007     

Theoretical study of the effect of frit quality on chromatography using computational fluid dynamics

Summary Frits at both ends of a chromatographic column, especially for a preparative column, have significant influence on the flow distribution within the column and thus the column efficiency. However, frits have received little attention from chromatographers in the past. Here a theoretical study was conducted with the aid of CFD software FLUENT to investigate the effect of frits on the performance of homogeneous and heterogeneous chromatographic columns. A dimensionless number,FQ, was applied to characterize frit quality. This study visualized how frit quality affects the flow distribution and the concentration band, the shape of eluted pulse at the colum exit and column efficiency. Simulation results show that the development length of the flow distribution is related toFQ but has nothing to do with the packing heterogeneity. The curvature of the concentration band in a column depends onFQ and packing quality. This study shows column efficiency can be improved significantly by increasingFQ and/or frit permeability.