Diels-Alder reaction volumes in the solid state and solution

The densities of anthracene, tetracyanoethylene, maleic anhydride, N-phenylmaleineimide, trans, trans-1,4-diphenylbuta-1,3-diene, and their Diels-Alder adducts were measured in the solid state and in solution at 25 °C. The reaction volumes in the solid state were calculated from the difference in molar volumes. They turned out to be low, close to each other (–4 to –11 cm³ mol^–1), and slightly different from the reaction volumes (–8±1 cm³ mol^–1) calculated from the van der Waals radii. The reaction volumes in solutions (–15 to –32 cm³ mol^–1) were found from the difference in partial molar volumes of the reactants in dioxane, acetonitrile, and 1,2-dichloroethane, The experimental Diels-Alder reaction volumes in solution are determined not only by the formation of new bonds in an adduct: a considerably higher contribution (to 75%) is made by a change in the volume of intermolecular empty spaces in solution on going from reactants to adducts.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2386–2390, November, 2004.     

Adsorptive stripping voltammetric determination of cobalt in the presence of dimethylglyoxime and cetyltrimethylammonium bromide

A sensitive procedure for determination of micro-traces of Co(II) by adsorptive stripping voltammetry is proposed. The procedure exploits the enhancement of the cobalt peak obtained by use of the system Co(II)–dimethylglyoxime–piperazine-1,4-bis(2-ethanesulfonic acid)–cetyltrimethylammonium bromide. Using the optimized conditions, a detection limit (based on the 3 criterion) for Co(II) of 1.2×10^–11 mol L^–1 (0.7 ng L^–1) was achieved. The calibration plot for an accumulation time of 30 s was linear from 5×10^–11 to 4×10^–9 mol L^–1. The procedure was validated by analysis of certified reference materials and natural water samples.     

Studies on recrystallised aluminium trihydroxide precipitates: The energetics of dissolution by sodium hydroxide solutions

Summary Aluminium hydroxide gels were recrystallised in high pH solution for 2–1000 hr to give a series of gibbsite powders of different surface areas, 1`11/2, P11/8, P11/48, P11/360 and P11/X; their average platelet lengths were 30, 60, 130, 260 and 450 nm. The dissolution equilibria of these powders in sodium hydroxide solutions of C=1-8 M were studied at 20° to 80°C.The equilibrium constants (for formation of diaquo-tetrahydroxoaluminate anion) increased with temperature and with increasing surface area; the K value for P11/2 was about four times that of P 11/X at 20 °C and about three times (that for P 11/X) at 80 °C. The dissolutions were endothermic; however, the value over this temperature range increased from –29.5 kJ mol<sup>–1</sup> (for P11/X) to –24.7 kJ (for P 11/2). This increase was related to the appreciable surface energies of the high surface-area materials.The (– G°) values increased with increasing temperature and in turn with increasing surface area; the (– G°) values for 1`11/2 dissolution at any temperature were about 4 kJ mol^–1 higher than those for P11/X dissolution.With 1 figure and 1 table     

Insect pheromones and their analogs

(Z)-hexadec-11-enal and (Z)-hexadec-11-1-yl acetate — components of the sex pheromone of insects of the generaHeliothis andManestra, respectively — have been synthesized by the condensation of undec-10-enal with hex-1-yne, deoxygenation of the heptadec-1-en-12-yn-11-ol formed via the corresponding tosylate to heptadec-1-en-12-yne, and the selective oxonolysis of the latter.Institute of Chemistry, Bashkir Branch, Academy of Sciences of the USSR, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 440–444, May–June, 1987.     

Mass-spectrometric study of the new alkaloids from plants of the family Liliaceae

A review is given of the mass spectra of alkaloids isolated from plants of the generaColchicum L.,Merendera ramond, family Liliaceae that are derivatives of homoproaporphine, homoaporphine, homomorphine, and allochlchiceine. The basic fragmentation pathways and the analytical indications of individual structural types and differences due to the mutual positions of the functional groups, substituents, and the unsaturation of individual rings are given.Yuldash Akhunbabaev Institute of Textiles and Light Industry, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 3–11, January–February, 1985.     

MD Simulation of an Infinitely Dilute Aqueous Solution of Formamide. Study of Thermodynamic, Structural, Dynamic, and Spectroscopic Properties

A molecular dynamics simulation of an infinitely dilute aqueous solution of formamide was carried out using an MP2-CP ab initio potential to describe the solute–solvent interaction. Various static and dynamic properties were calculated using this potential obtained by fitting the formamide–water interaction energies to a 12-6-1 type function. These energies were calculated with the supermolecular approach by considering the MP2 correlation and the CP superposition. The values presented for the thermodynamic functions (H _S–W = –25.5 kcal-mol^–1 and G _S–W = –15.9 kcal-mol^–1), the structure of the first hydration layer (with 5 to 6 solvent molecules bonded to the solute), the solute's translational (D= 1.50 × 10^–5 cm²-s^–1) and rotational ( = 6.6 ps) mobility in the surrounding medium, and the positions of the H···O hydrogen bond spectral bands corresponding to these motions (_i = 92, 246, 379, and 636 cm^–1), are in agreement with the available results for this and other similar systems. In addition, the results are compared with those obtained by using parameters transferred from other systems. We observed that these values depend strongly on the potential used and concluded that it is advisable to avoid the use of such parameters.     

Ion-Selective Electrodes Based on Adamantylcalix[4,8]arenes for the Determination of Alkali Cations

Calix[4,8]arenes bearing adamantyl substituents in the upper rim and ethoxycarbonylmethoxy groups in the lower rim of the macrocycle were proposed as ionophores in membranes of ion-selective electrodes (ISEs) for determining alkali cations. Depending on the number of phenolic fragments (n) in the calixarene molecule, ISEs respond to either sodium (n = 4) or cesium (n = 8) ions. Sensors based on membranes that, along with ionophores, contain tetraphenyl borate ions as a lipophilic additive are selective for Na and Cs ions in the presence of other alkali metals. They exhibit almost theoretical responses over the concentration range from 1 × 10^–4 to 1 × 10^–1 M at pH 5.5–12 for Na-SE and pH 3–11 for Cs-SE, respectively.     

Calorimetric study of phase transitions in the thiourea carbon tetrachloride inclusion compound

Heat capacities of the inclusion compound (thiourea)_3.00CCl₄ have been measured in the temperature range 15–300 K. A first-order phase transition was found at 41.3 K and a second-order transition at 67.17 K. The enthalpy and entropy of the transition are 149 J mol^–1 and 3.7 J K^–1 mol^–1 for the former, and 241 J mol^–1 and 3.9 J K^–1 mol^–1 for the latter. A divergent expression C = A{(T _c –T)/T _c} ^– was fitted to the excess heat capacity of the upper phase transition. The best-fit parameters wereA = 7.4 J K^–1 mol^–1,T _c = 67.166 K and = 0.31. Possible types of molecular disorder in the high temperature phase are discussed in relation to the transition entropy and the molecular and site symmetries of the guest molecule. The heat capacity of the lowest temperature phase was unusually large and may indicate the existence of very low frequency vibrational modes or labile configurational excitation of the guest molecule. Standard thermodynamic functions were calculated from the heat capacity data and are tabulated in the appendix.Contribution No. 11 from the Microcalorimetry Research Center.     

Enhancing effect of DNA on chemiluminescence from the decomposition of hydrogen peroxide catalyzed by copper(II)

In the absence of any special luminescence reagent, emission of weak chemiluminescence has been observed during the decomposition of hydrogen peroxide catalyzed by copper(II) in basic aqueous solution. The intensity of the chemiluminescence was greatly enhanced by addition of DNA and was strongly dependent on DNA concentration. Based on these phenomena, a flow-injection chemiluminescence method was established for determination of DNA. The chemiluminescence intensity was linear with DNA concentration in the range 2×10^–7–1×10^–5 g L^–1 and the detection limit was 4.1×10^–8 g L^–1 (S/N=3). The relative standard deviation was less than 3.0% for 4×10^–7 g L^–1 DNA (n=11). The proposed method was satisfactorily applied for determination of DNA in synthetic samples. The possible mechanism of the CL reaction is discussed.     

Determination of subnanomolar concentrations of cobalt by adsorptive stripping voltammetry at a bismuth film electrode

Procedures for trace cobalt determinations by adsorptive stripping voltammetry at in situ and ex situ plated bismuth film electrodes are presented. These exploit the enhancement of the cobalt peak obtained by using the Co(II)–dimethylglyoxime–cetyltrimethylammonium bromide–piperazine-N,N-bis(2-ethanesulfonic acid) system. The calibration graph for an accumulation time of 120 s was linear from 2 × 10^–10 to 2 × 10^–8 mol L^–1. The relative standard deviation from five determinations of cobalt at a concentration of 5 × 10^–9 mol L^–1 was 5.2%. The detection limit for an accumulation time of 300 s was 1.8 × 10^–11 mol L^–1. The proposed procedure was applied to cobalt determination in certified reference materials and in tap and river water samples.     

Synthesis of Drim-9(11)-en-8α- and -8β-ols from Drimenol

Drim-9(11)-en-8α-ol and drim-9(11)-en-8β-ol were synthesized in six steps from drimenol. Drimenol was oxidized by P₂O₅ and DMSO to drimenal, which isomerized with p-TsOH into isodrimenal. Isodrimenal was reduced by NaBH₄ into isodrimenol, epoxidation of which by m-CPBA gave a mixture (3.4:1) of α- and β-epoxyisodrimenols. These reacted with tosyl chloride in Py to give a mixture of α- and β-epoxyisodrimenol tosylates. Treatment of the tosylate mixture with KI and then Ph₃P produced a mixture of drim-9(11)-en-8α- and -8β-ols that was separated chromatographically. The overall yield was ∼26%.__________Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 152–155, March–April, 2005.     

Nuclear magnetic resonance study of Li and H diffusion in the high-temperature solid phase of LiBH4

In order to study the atomic jump motions in the high-temperature solid phase of LiBH₄, we have measured the ¹H and ¹¹B nuclear magnetic resonance (NMR) spectra and the ¹H, ⁷Li and ¹¹B spin–lattice relaxation rates in this compound over the resonance frequency range of 14–34.4 MHz. In the temperature range 384–500 K, all the spin–lattice relaxation data are satisfactorily described in terms of a thermally activated jump motion of Li ions with the pre-exponential factor τ₀=1.1×10⁻¹⁵ s and the activation energy E_a=0.56 eV. The observed frequency dependences of the spin–lattice relaxation rates in this temperature range exclude a presence of any distributions of the Li jump rate or any other jump processes on the frequency scale of 10⁷–10¹⁰ s⁻¹. The strong narrowing of the ¹H and ¹¹B NMR lines above 440 K is consistent with the onset of diffusive motion of the BH₄ tetrahedra.     

Vanilline Alkanoates in the Synthesis of Hexahydrobenzacridine and Octahydroxanthene Derivatives

Cascade heterocyclization of 1,3-cyclohexanedione and dimedone with 2-naphthylamine and vanilline esters gave derivatives of 2-methoxy-4-(alkyl-11-oxo-7,8,9,10,11,12-hexahydrobenz[a]acridin-12-yl)- and 2-methoxy-4-(alkyl-1,8-dioxo-2,3,4,5,6,7,8,9-octahydro-1H-xanthen-9-yl)phenyl esters of aliphatic (C₁– C₄ ) carboxylic acids.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 654–658.Original Russian Text Copyright © 2005 by Kozlov, Basalaeva.     

Iridoids of plants of the genusGentiana from the family Gentianaceae

The review contains the results of an analysis of the literautre on the study of plants of the genusGentiana, family Gentianaceae Juss. The biological properties of the iridoid compounds are described. Their physicochemical constants are also given: the name of the substance, the melting point, the angle of rotation, details of the UV, IR and PMR spectra, and literature relating to them. The distribution of iridoid compounds in plants over the sections of the genusGentiana is given in the form of tables, and the material is discussed correspondingly.All-Union Scientific-Research Institute of Pharmacy, Moscow. Translated from Khimiya Prirodnikh Soedinenii, No. 1, pp. 3–11, January–February, 1987.     

Membrane separation of ions for the preparation of pure solutions of heteropolycompounds

Reverse osmosis was used for the separation of various types of heteropolyanions (HPA): [PW₁₁O₃₉M(H₂O)] ^k– (M = Co^II, Fe^III, Cr^III), [(PW₁₁O₃₉Fe)₂O]^10– , and [PW₁₁O₃₉ · Fe _n O _x H _y ] ^p– from contaminant ions NO₃ ^– and Na⁺ that are usually introduced into the solution in the synthesis of HPA.Translated fromIzvestiya Akodemii Nauk. Seriya Khimicheskaya, No. 4, pp. 1009–1011, April, 1996.     

Insect pheromones and their analogs. LVIII. Synthesis of hexadeca-7Z,11E-dien-1-yl acetate — a component of the sex pheromones ofPectinophora gossypiella andSitotroga cerealella

A new synthesis of hexadeca-7Z,11E-dien-1-yl acetate — a component of the sex pheromones of the pink bollworm (Pectinophora gossypiella) and the Angoumois grain moth (Sitotroga cerealella) — is proposed that is based on a thermal Claisen rearrangement.Scientific-Research Institute of Small-Tonnage Chemical Products and Reagents, Ufa, fax 8-(3472) 43 17 31. Ufa State Petrotechnical University. Institute of Petrochemistry and Catalysis, Academy of Sciences of the Republic of Bashkortistan, Ufa, fax-8(3472) 31 27 50. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 231–234, March–April, 1998.     

Galactomannan from <Emphasis Type="Italic">Gleditsia macracantha</Emphasis> Seeds and Its Biological Activity

Galactomannan, a nontoxic compound that exhibits in experiments with intact rats a slight hypocholesterinemic and hypoglycemic activity, was isolated from the coating of Gleditsia macracantha seeds. It prevents significantly the development of experimental hyperglycemia and diabetes when administered simultaneously with alloxan.__________Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 10–11, January–February, 2005.     

Metabolites of the marine fungus <Emphasis Type="Italic">Humicola fuscoatra</Emphasis> KMM 4629

A new sesquiterpene of the caryophyllene series, fuscoatrol A (1), and known compounds, 11-epiterpestacin (2) and -nitropropionic acid (3), were isolated from the marine fungus Humicola fuscoatra (Traaen) KMM 4629 associated with the Kuril colonial ascidium. The structure of 1 was established on the basis of X-ray diffraction data and 2D NMR spectroscopy. The antimicrobial and cytotoxic activities of compounds 1–3 were studied.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2534–2537, November, 2004.     

The lactones ofFerula malacophylla

Summary 1. From the roots ofFerula malacophylla three sesquiterpene lactones have been isolated: talassin A and the two new ones — malaphyll and malaphyllin.2. On the basis of spectral and chemical characteristics, for malaphyll is proposed the structure of 1-oxo-11-seneciocyloxy-6-veratroyloxyguaia-2,8-dien-4,5-olide, and for malaphyllin 11-acetoxy-1-oxo-6-veratroyloxyguaia-2,8-dien-4,5-olide.V. L. Komarov Institute of Botany, Academy of Sciences of the Azerbaidzhan SSR, Baku. All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 445–449, July–August, 1978.