Nitrosation of mefenorex in the presence of cyclodextrins

- and -Cyclodextrin (CD) and heptakis-2,6-di-O-methyl--cyclodextrin (DIMEB) form soluble inclusion compounds with mefenorex (MEF); with -CD a partial inclusion occurs. No solid inclusion compound could be obtained with the four CDs. -, -CD and DIMEB, but not -CD, enhance the nitrosation rate of MEF if the nitrosation assay procedure (NAP test) is applied. During this reaction with - and -CD, solid inclusion compounds of the CDs and nitrosomefenorex (NMEF) precipitate.Part of the Ph.D. thesis of V. Wedelich, Freie Universität Berlin, 1985.     

Charge-transfer complexes betweenp-toluidine and iodine in solution: A kinetic study

The kinetics of charge-transfer interaction betweenp-toluidine and iodine in methylene chloride was investigated in depth. Thethermal process of formation of theinner complex was found to proceed to an equilibrium. Thephotochemical process follows a different reaction coordinate, going through the formation of an exciplex between the excitedouter complex and the amine ground state. In both cases the same ionic complex (Am ₂I⁺I ₃ ^– , whereAm stands forp-toluidine) was detected as the final product.

---

Kinetische Untersuchung der Charge-Transfer-Komplexe zwischenp-Toluidin und Jod

Zusammenfassung Die Kinetik der Charge-Transfer-Wechselwirkung zwischenp-Toluidin und Jod in Methylenchlorid wurde ausführlich untersucht. Derthermische Prozeß, der zur Bildung desinner-Komplexes führt, geht bis zu einem Gleichgewicht. Derphotochemische Prozeß folgt einer unterschiedlichen Reaktionskoordinate und verläuft über die Bildung eines Exziplexes zwischen dem angeregtenouter-Komplex und dem Amin im Grundzustand. In beiden Fällen wurde derselbe ionische Komplex (Am ₂I⁺I ₃ ^– , wobeiAm fürp-Toluidin steht) als Endprodukt festgestellt.

     

Synthesis and biological activity of yuccagenin bisrhamnoside

The two hydroxyls of yuccagenin can be glycosylated by Koenigs-Knorr condensation with acetobromorhammose in dichloroethane in the presence of mercuric cyanide. The bisrhamnoside of yuccagenin markedly lowers the cholesterol and triglyceride content in blood serum of healthy animals and animals with experimental hyperlipidemia.Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 242–243, May–June, 2000.     

Band structure of nonclassical polymers

It is shown that fully conjugated alternant nonclassical polymers are comparatively stable systems as a result of the considerable delocalisation energy.The energy characteristics of the polymers are strongly determined by the electron spin distribution of the degenerate nonbonding molecular orbitals; the full spin configuration,S>0, is favoured. The spin densities depend on the electron correlation and alternate; this corresponds to a ferrimagnetic state of the polymer at 0°K.     

Configuration interaction methods for improving unrestricted Hartree-Fock spin densities

Limited Configuration Interaction wave functions based on Unrestricted Hartree-Fock natural orbitals are found to be easy to compute and to give much more satisfactory spin densities than are provided by techniques currently in use.     

Conformational analysis of dimethylphosphate with quantum-mechanical and classical methods

In order to shed light on the conformational behavior of polynucleotide chains, and in particular to clarify the origins of the barriers to internal rotation in the phosphodiester linkage, we computed, with a quantum-mechanical ab initio procedure, the energies associated to 86 combinations of the two torsion angles in the dimethylphosphate anion (CH₃O)₂PO₂ ^–, and then we sought for an analytical expression apt to reproduce these energies with the highest possible accuracy. An excellent agreement (standard deviation of the fitted energies from the ab initio energies 0.28 kcal/mole) with the quantum-mechanical calculations was reached with a potential consisting of four terms: 1) a 6–12 Lennard-Jones contribution, in which different parameters are used to describe the interactions of methyls with the ester oxygens and with the anionic oxygens; 2) a contribution with twofold periodicity, accounting for the anomeric effects connected to the interactions between the lone pair electrons and the polar bonds of phosphorus with the anionic oxygens; 3) a contribution with threefold periodicity, representing the usual bond-staggering term; and 4) a Coulombic contribution, arising from electrostatic interactions between partially charged atoms.     

A quantum-mechanical study of the interaction of methylglyoxal with guanine

Ab initio self-consistent field molecular orbital computations on the relative stabilities of the different possible intermediate adducts for the reactions between methylglyoxal and guanine, as well as the evaluation of the relative stabilities of the two different possible final cyclic products (IIIb and IIIc) point all to the conclusion that it is the addition product in which the methyl group is close to the amino nitrogen which is the most stable one.     

Reaction of β-Cyclodextrin with N-2,3-Epoxypropylphthalimide. Preparation, Characterisation and Study of a New Substituted Cycloheptaamylose. Effects on the Water Solubility of Drugs

The reaction of -cyclodextrinwith N-2,3-epoxypropylphthalimide yielded a set of newamorphous host compounds with high solubility whichwas transmitted to the corresponding host-guestcomplexes. The structure was determined by comparing the 1H- and 13C-NMR spectra with those of theparent compound, the degree of substitution by integration of the corresponding NMR signals, and C, H,and N elemental analysis.     

Multiplicity of the ground state of large alternant organic molecules with conjugated bonds

The multiplicity and the full spin of the ground state of large alternate molecules with conjugated bonds are considered. It is strictly shown that if the numbers of starred and unstarred atoms (say, carbon) differ from each other the full spin of the molecule is more than zero. Some possible planar and linear molecules having the full spin to be proportional to their sizes are presented. Particularly, they would be ferromagnets at infinite sizes.     

Influence of the Structure of Steroid Hormones on Their Association with Cyclodextrins: A High-Performance Liquid Chromatography Study

The association constants of fourteen steroid hormones with - and -cyclodextrin were measured in methanol-water (20 : 80 v/v) at 35 °C using the chromatographic Hummel-Dreyer method. It was found that the greatest influence on the association constants is the structural features of ring A of these compounds but the substituents of ring D also alter the complex stability to an appreciable degree. The measured association constants were considerably greater than the corresponding values measured previously in the medium containing more methanol (45 instead of 20%).     

NMR Investigations of the Inclusion of Thyroxine and Derivatives in Natural Cyclodextrins

Thyroxine T4 and its derivatives (T3, T2) are very sparingly soluble in aqueous solutions even in the form of salts. In the presence of or -cyclodextrins and in buffered basic solution, their solubilities are increased by inclusion in the cavity. The inclusion of these hormones in cyclodextrins was investigated by 1H-NMR in order to derive the influence of the number and position of the iodine atoms, and of the ionization state of the phenol group on the inclusion geometries.     

Effect of the melt annealing time on the crystallization of nylon-6 with various molecular weights

The effect of melt annealing duration at 260 °C-high above melting temperature on the crystallization of nylon-6 with various molecular weights (between 5 800 and 255 500) using dilatometric and calorimetric (DSC) techniques has been studied. The samples were laboratory synthesized, purified and characterized by GPC. It was found that the crystallization behavior of nylon-6 depends strongly on the melt annealing duration as well as on the molecular weight. This effect is explained by the gradual destruction of the crystallization centers during annealing of the melt. The experimental data support the well known memory effect and the recently observed accumulative memory effect on the same polymer     

Synthesis of 4′4″(5″)-dibenzo-18-crown-6-disulfonic acid disalsolidinide,disalsolinide, and dianabasinide

New disulfamides of dibenzo-18-crown-6 with salsolidine, salsoline, and anabasine were prepared by condensation of the corresponding alkaloids with 4,4(5)-dibenzo-18-crown-6-disulfonyl chlorides.Presented at the 5th International Symposium on the Chemistry of Natural Compounds (Tashkent, Uzbekistan, May 20–23, 2003).Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 413–415, September–October, 2004.     

Triterpene Glycosides from Plants of the Astragalus Genus. Structure of Cyclounifolioside A from Astragalus unifoliolatus

The known compound oleanolic acid (1) and a new cycloartane glycoside cyclounifolioside A (2), which has the structure 6,16-di-O-acetyl-24R-cycloartan-6,16,24,25-pentaol 3-O--D-glucopyranoside, were isolated from Astragalus unifoliolatus Bunge. The structures of the isolated compounds were established using chemical transformations and two-dimensional spectra (TOCSY, ROESY, HMBC, HSQC, COSY).     

Studies of the energy spectrum of α, ω- substituted polymethine chains. II. Polymethine chains with odd number of methine groups

The analysis of the experimental data for the energy of the longest wavelength optical transitions _n,opt of substituted polymethines X (CH)_2n+1 X shows that in the asymptotic case (n) _,opt does not tend to zero, as it follows from the empirically established correlations, but has a finite, non-zero value. It is shown that the energy gap of odd polymethines is the same as that of the even polymethines - the polyenes (E 2 eV). The substituents (X N, O, B) are responsible for the appearance of levels in the gap. These, depending on the substituent character, are vacant (X B) or occupied (X N, O). The transition from or to such a level determines the longest wavelength optical transition energy of polymethines.     

Photochemical addition of diethyl ether to β,β,β',β'-tetrakis(trifluoromethyl)divinyl ether

The 1:1 adducts of diethyl and ,,','-tetrakis(trifluoromethyl)divinyl ether (1),i.e., 3,5-(ee)-bis[2,2,2-trifluoro-1-(trifluoromethyl)ethyl]-2,6-dimethyl-1,4-dioxane (2) (3 isomers) and 4-ethoxy-1,1,1-trifluoro-2-trifluoromethyl-3-[3,3,3-trifluoro-2(trifluoromethyl)propenyloxy]pentane (3), have been obtained by UV-irradiation of a solution of divinyl ether1 in diethyl ether. The X-ray structural investigation of the all-(e)-isomer of dioxane (2) has been carried out.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 85–88, January, 1994.     

Theoretical assignments of the electronic spectrum of acetylene

Non empirical calculations of energies and properties of some excited states of acetylene are presented. A frozen core approximation is used and excitations to , and MO's are taken into account. Both valence and Rydberg states are considered. Assignments of the UV and electron impact spectra are proposed and some questions are raised.     

Investigation of the Regio- and Stereochemistry of the [2+4] Cyclocondensation of 3,4-Dihydroisoquinolines with 2-Acetyl-4-hydroxycyclohexane-1,3-dione. Synthesis and Properties of the Regioisomeric 15- and 17-Hydroxy Derivatives of 8-Aza-D-homogona-12,17a-diones

The 15- and 17-hydroxy derivatives of 8-aza-D-homogona-12,17a-diones were obtained by the annelation of 3,4-dihydroisoquinolines with 2-acetyl-4-hydroxycyclohexane-1,3-dione. It was shown that the reaction proceeds stereoselectively with the intermediate formation of 9,15- and 9,17-trans isomers. The probable mechanism and certain aspects of the interconnection between the structural and physicochemical characteristics of the obtained compounds are discussed.