正交试验法研制多烷基二氢化茚

双环苯型麝香化合物对香料工业具有重要意义。如粉檀麝香是合成麝香料。而1,1,2,3,3,5-六甲基-2.3-二氢化茚(HMI)则是制备粉檀麝香的母体化合物, 其经酰化后即可得到粉檀麝香。本文以对甲基异丙苯和2-甲基-丁烯-[2]为原料, 合成了HMI。     

Chemical applications of group theory and topology

The following procedure is described for investigating the qualitative dynamics of simple chemical systems: 1) A so-called influence diagram is generated representing the relationships between the reference reactants (phase-determining intermediates); 2) This influence diagram is used to generate a p/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">truth tablep/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> indicating possible transitions between state vectors representing the signs of the time derivatives of of the reference reactant concentrations; 3) The truth table is used to determine a state transition diagram representing the flow topology around unstable equilibrium points; 4) The characteristic equation of the adjacency matrix of the influence diagram is solved in order to determine the presence of such unstable equilibrium points. The two types of qualitative dynamics possible for chemical systems containing two reference reactants and one feedback circuit are bifurcation between two attracting regions (bistability) and limit cycle oscillation. However, in two reference reactant systems oscillation requires an additional self-activating loop to generate the unstable equilibrium point required for its realization. Bistability and limit cycle oscillation are also two of the possible types of qualitative dynamics for chemical systems containing three reference reactants. However, chemical systems with three reference reactants and two or more feedback circuits can also contain interlocking limit cycles, which can lead to toroidal oscillations or chaos. The influence diagrams are given for the systems exhibiting these various types of dynamic behavior along with a summary of the important properties of all 729 possible influences for simple chemical systems containing three reference reactants.     

The inclusion complex of piromidic acid with dimethyl-β-cyclodextrin in aqueous solution and in the solid state

Inclusion complex formation of piromidic acid (PA) with dimethyl-p50q46qm188524t7/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin (DM-p50q46qm188524t7/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD) in aqueous solution and in the solid state was confirmed by the solubility method, differential scanning calorimetry (DSC) and proton nuclear magnetic resonance (p>1p>H-NMR) spectroscopy. The apparent stability constant,K _c , of the complex was estimated to be 244 Mp>–1p>. The stoichiometry of the complex was given as the ratio 1:2 of PA to DM-p50q46qm188524t7/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD. The dissolution rate of the PA/DM-p50q46qm188524t7/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD complex was much greater than that of intact PA.Presented at the Fourth International Symposium on Inclusion Phenomena and the Third International Symposium on Cyclodextrins, Lancaster, U.K., 20–25 July 1986.     

Synthetic receptors based on calix[4]arene functionalized at the lower rim in molecular recognition of dicarboxylic, α-hydroxycarboxylic,and α-amino acids

New calix[4]arenes, di- and tetrasubstituted at the lower rim, with different functional groups were synthesized. They were studied as carriers of a series of dicarboxylic and p844841561325238/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-hydroxycarboxylic acids through a liquid impregnated membrane. The calix[4]arenes under study are capable of molecular recognition of oxalic acid in the series of structurally similar dicarboxylic and p844841561325238/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-hydroxycarboxylic acids. The regularities found make it possible to change purposefully the receptor ability of 1,3-disubstituted calix[4]arenes by variation of the nature of substituents.     

Investigation of the phosphinyl analog of α-ketoglutaric acid

It was shown byp>31p>P andp>13p>C NMR spectroscopy that methyl(3-carboxy-3-oxopropyl)phosphinic acid (4-methylhydroxyphosphinyl-2-oxobutyric acid) (1) and the amide (2) of the latter exist in keto forms in non-aqueous solutions. In aqueous solutions an equilibrium between the keto,gem-diol, and enol forms has been observed. The proportions of the diol and enol forms increase as the acidity of the media increases. Silylation of acid 1 with hexamethyldisilazane gives the tris(trimethylsilyl) derivative of enol form (3) (Z- andE-isomers).Translated fromIzyestiya Akadetnii Nauk. Seriya Khimicheskaya, No. 1, pp. 125–128, January, 1994.     

Reactions of hexamethylditin and trimethyltin sulfide withN-thio-derivatives of phthalimide

The initial formation of organotin derivatives with Sn-S-N bonds in heterolytic reactions of hexamethylditin or trimethyltin sulfide withN-(chlorothio)phthalimide is suggested. Subsequent interaction of these compounds with sulfenyl chloride affordsN, Np51286176/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-thioorN, Np51286176/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-dithiobisphthalimide. Homolytic reaction of hexamethylditin withN, Np51286176/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-dithiobisphthalimide also occursvia an organotin intermediate, which, in the absence of a nucleophilic reagent, eliminates sulfur and converts intoN-trimethylstannylphthalimide.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2111–2114, December, 1993.     

Ab initio calculation of 4-ClC6H4CH2Cl and peculiarities of electron density distribution in this molecule

Ab initio calculation of the 4-ClC₆H₄CH₂Cl molecule was performed by the restricted Hartree-Fock method in the split valence 6–31 G* basis set with complete optimization of its geometry. Populations of p-orbitals of atoms of this molecule were analyzed.p>35p>Cl NQR frequencies and asymmetry parameters of the electric field gradient onp>35p>Cl nuclei were estimated on the basis of the populations of valent p-orbitals of CI atoms and their components. Good conformity with the experimental values was obtained when only less diffuse components of p-orbitals were used in calculations of populations.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 823–826, April, 1996.     

Solubility Enhancement of Low Soluble Biologically Active Compounds by β-Cyclodextrin and Dimethyl-β-cyclodextrin

The solubility enhancement of triflumizole by complexation with p4586834/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin and with dimethyl-p4586834/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin is compared with respect to the different physico-chemical properties of the host molecules. Although the inclusion reaction constants are rather similar for both complexation reactions, a completely different temperature dependence of the host-guest interaction is observed, which indicates a change of the reaction mechanisms. Moreover, the influence of ethanol as cosolvent is studied.     

Polygrammal Symmetries in Biomacromolecules: Heptagonal Poly d(As4T)· poly d(As4T) and Heptameric α-Hemolysin

Polygrammal symmetries, which are scale-rotation transformations of star polygons, are considered in the heptagonal case. It is shown how one can get a faithful integral six-dimensional (6-D) representation leading to a crystallographic approach for structural properties of single molecules with a sevenfold point symmetry. Two biomacromolecules have been selected in order to demonstrate how these general concepts can be applied: the left-handed Z-DNA form of the nucleic acid poly d(Asp>4p>T) · poly d(Asp>4p>T), which has the line group symmetry 7₆22, and the heptameric transmembrane pore protein α-hemolysin. Their molecular forms are consistent with the crystallographic restrictions imposed on the combination of scaling transformations with sevenfold rotations. This all is presented in a two-dimensional (2-D) description, which is natural because of the axial symmetry.