Conductivities of 1∶1 salts in 2-cyanopyridine

Electrolytic conductivities of eight simple 11 electrolytes have been measured in dilute solutions of 2-cyanopyridine (2CNP) at 30°. Infinite dilution mobilities and association constants were calculated using the Fuoss-Hsia equation. With the exception of LiCF₃SO₃ all salts show very little association, consistent with the very high dielectric constant of 2CNP. The weak association which does occur is attributed to weak ion-solvent interactions. No evidence was found for triple ion formation. Conductivities of concentrated solutions of LiAsF₆ in 2CNP increase slowly with concentration reaching a maximum at a concentration of around 0.65 mol-dm^–3. These conductances are slightly lower than those in propylene carbonate which has a lower dielectric constant and a higher viscosity. Conductivities of concentrated LiAsF₆ solutions in 2CNP mixtures with acetonitrile vary monotonically, consistent with solution viscosities, and show no sign of the maximum commonly observed in mixed organic solvents.     

X-ray crystallographic studies and molecular calculations on 1∶1 inclusion complexes of cholic acid with acetophenone and its derivatives

Molecular calculations were applied to four channel-type inclusion complexes of cholic acid (CA) with acetophenone or its derivatives (3-, 4-fluoroacetophenone and 2-chloroacetophenone). According to the calculated results, both the total and van der Waals interaction energies between channel and included guests depend on the channel form determined by the guest species. Similarly, the channel form is responsible for the dipole moment of the channel. Further examination of the results suggests that dipole-dipole interaction does not play an important role in the determination of the guest orientation. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82193 (26 pages).     

Solvent extraction of sodium picrate with 15-crown-5 into carbon tetrachloride. The determination of the dimer-formation constant of a crown ether-univalent metal salt 1∶1∶1 complex

The theory is derived to determine the dimer-formation constant,K ₂, of a crown ethermetal salt 111 complex in organic solvents of low dielectric constant by solvent extraction. The theoretical predictions are verified experimentally by extraction of sodium picrate (NaA) with 15-crown-5 (15C5) into carbon tetrachloride. All the experiments were conducted at 25°C. The logK ₂ value of the Na(15C5)A complex in carbon tetrachloride has been determined to be 4.05±0.11. Moreover, the partition constant of the complex is calculated.     

Enthalpies of dilution for 1∶3 and 3∶1 electrolytes aqueous solutions

The enthalpies of dilution for aqueous solutions of [Co(cn)₃)]Cl₃, [Co(pn)₃)]Cl₃ and [Co(tn)₃]Cl₃, (whereen=1,2-diaminoethane,pn=1,2-diaminopropane, andtn=1,3-diaminopropane) have been measured at 298.15 K, and up to 1 mol kg^–1+, using a new large isoperibol calorimeter by the long-jump method. Relative apparent molar enthalpies,_291-01, have been extracted as an empirical equation relatingL andm. We have compared our complex salts with the 31 and 13 aqueous systems found in the literature. Theoretical predictions for 13 and 31 electrolytes in the Restricted Primitive Model are also shown.This work was supported in part by CICYT (M.E.C., Spain) under Research Project No.: PB92-0553.     

Clathrate and inclusion compounds. Part 11 [1]. A pre-resonance Raman study of the β-quinol/SO2 clathrate

A pre-resonance Raman study of the yellow -quinol/SO₂ clathrate has been carried out using 609.8, 586.8, 514.5, 488.0 and 457.9 run excitation. Pre-resonance enhancement is observed for the guest v_l (Al) band at 1147 cm^–1 and the host band at 1257 cm^–1. These observations are consistent with a charge transfer interaction arising from the LUMO of S0₂ (S 3pz) and the HOMO of quinol, which consists mainly of the ring electrons.     

New synthesis and complexing properties ofp-tert-butyldihomooxacalix[4]arene. Structure of its 1∶2 complex with tetrahydrofuran

A new method is described for the synthesis of isolatedp-tert-butyldihomooxacalix[4]arene (CALO) with a 24% yield. The ability of CALO to form complexes in the solid state with small neutral molecules has been studied; the potential guests were common solvents bearing various chemical functions. The powder obtained after evaporation of the solvent has been characterized by the X-ray powder diffraction technique. Analysis of the patterns shows the non-complexation of linear alkanes and alcohols, but formation of complexes when the guest is cyclic or when it bears an amine or a ketone function. As illustration of the possible arrangement of molecules in complexes, the structure of the 1:2 complex with tetrahydrofuran (THF) is presented: the crystals are monoclinic, space groupP2₁/c,a=9.459(2) Å,b=17.286(2) Å,c=30.469(6) Å, =92.52(2)^o,V=4977(2) ų,Z=4,D _c=1.099 Mg m^–3, =1.54178 Å, =5.6 cm^–1,R=0.086 for 3590 reflections withF>4 (F); one of the THF molecules is inside the cavity of the macrocycle, while the other, in the interhost space, exhibits disorder. In the CALO molecule, three out of the fourtert-butyl groups are disordered which may induce the disorder of the THF molecule. Supplementary Data: relating to this article are deposited with the British Library: Supplementary Publication No. Sup. 82191 (29 pages).     

Synthesis and characterization of praseodymium-2-hydroxypropyl-β-cyclodextrin inclusion complex

Journal of Radioanalytical and Nuclear Chemistry - The inclusion complex of PrCl3-XH2O-2-hidroxypropyl-β-cyclodextrin (Pr-2HPβCD) was prepared to increase the solubility and stability of...     

Preparation and characterization of the 1:1 inclusion compound γ-cyclodextrin/[Ni(dmit)2]1-

Abstract

The preparation of a 1:1 inclusion compound involving γ-cyclodextrin and bis(4,5-dimercapto-1,3-dithiole-2-thionato)nickelate (III) complex ion, [Ni(dmit)₂]^1-, is reported. The inclusion complex is characterized by UV-visible and Raman spectroscopy, thermal analysis and X-ray powder diffractometry.     

Host-guest binding in two coordinatoclathrates of 1,1′-binaphthyl-2,2′-dicarboxylic acid. x-ray crystal structures of the inclusion compounds with 1-propanol (2 : 1) andt-butanol (1 : 1)

1,1'-Binaphthyl-2,2'-dicarboxylic acid (1) forms crystalline inclusion compounds with 1-PrOH (2:1) andt-BuOH (1:1). X-ray crystal structures of the two inclusion compounds are reported. Crystals of1·1-PrOH (2: 1) show triclinic ( ) symmetry with the unit cell dimensionsa = 10.160(1),b = 14.050(2),c = 15.167(1) Å = 100.37(1), = 104.40(1), and =94.82(1)°. Crystals of1s·t-BuOH (1: 1) are monoclinic (P2₁/n) with the cell dimensionsa = 10.603(5),b = 14.377(4),c = 15.664(7) Å, = 104.24(4)°. In both structures, H-bonded loops involving host –000H functions and guest –OH groups establish the supramolecular association. They relate these coordinatoclathrates to previous alcohol inclusions of1. Due to the unusual 2:1 (host: guest) stoichiometry, additional dimer-like interactions between –000H groups of host molecules are found in the 1-PrOH inclusion compound. From the point of view of topology these structures can be referred to as channel inclusion compounds.     

NixZry(x:y=1∶2或2∶1)团簇的量子化学研究

根据化学键理论和拓扑学原理,设计了非晶态团簇NixZry(x:y=1∶2 或2∶1, x+y≤9)的几十种可能的构型,并应用量子化学从头算方法对它们的几何构型进行了优化,分析比较了这些构型的能量和稳定性。结果表明对于NixZry(x:y=1∶2)低对称性的平面构型最稳定,而NixZry(x:y=2∶1)三棱柱构型最稳定。这可能是由于两者外层价电子的数量差异所致： Zr仅有4个价电子,较适宜配位数低的平面构型,而Ni（4s23d8),更适宜立体构型。     

2-Benzopyrylium salts. 41. Intramolecular transformations of 4-1′-dimers of α-unsubstituted 2-benzopyrylium salts

Recyclization reactions of 4-1-dimers of 2-benzopyrylium salts leading to naphthalene derivatives are described. A new variant of the intramolecular Cannizzaro rearrangement has been discovered.For communication 40, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 175–180, February, 1991.     

Some Structural and Thermodynamic Aspects of Solvation of Single Ions. 2. Salt Effects in Aqueous Solutions of 1–1 Electrolytes

The ionic coefficients of the pair interionic interaction in aqueous solutions of 1–1 electrolytes at 298 K were determined from the real activity coefficients of single-charged single ions using the McMillan–Mayer formalism. Analysis of the results of calculations revealed that salt effects are stronger in the case of cations. The weakening of cation hydration (increased negative hydration) and the strengthening of anion hydration (increased positive hydration) enhance the mutual salting of cations and anions. It is shown that the structural effects of hydration produce a strong effect on the interionic interaction in solutions.     

Rearrangement of 1-oxa-2-azoles. 5. Synthesis and rearrangement of α-oximodimethyl-hydrazones of 1,2,4-oxadiazolyl-3-glyoxal

The acid halides of 1,2,4-oxadiazol-3-carbohydroxamic acids react with formaldehyde dimethylhydrazone to give the corresponding -oximohydrazones, which with hydrochloric acid rearrange to yield the dimethylhydrazone of 3-amino-4-formylfurazane. In the absence of an acid catalyst, the 5-trifluoromethyl derivative undergoes a rearrangement to give 1-dimethylamino-4-nitroso-3-trifluoroacetamidopyrazole.For Communication 4, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 976–978, July, 1991.     

Effects of inclusion of cetirizine hydrochloride in β-cyclodextrin

Following the preparation of inclusion complex of cetirizine (CTZ) and β-cyclodextrin (β-CD), the compound was investigated to assess the possibility of modifying the physicochemical properties (solubility, release, stability, permeability) of CTZ after complexation that are vital for subsequent formulation studies involving the said complex. Changes in FT-IR/Raman spectra, DSC thermograms and XRD diffractograms confirmed the formation of a CTZ–β-CD system. Hydrophilic interaction chromatography with a DAD detector was employed to determine alterations of the CTZ concentration during studies following complexation. An analysis of a phase-solubility diagram of c_CTZ?=?fc_β-CD indicated a linear rise in the solubility of CTZ as the concentration of β-CD increased. The inclusion of CTZ in a system with β-CD significantly reduced the instability of CTZ in the presence of oxidizing factors. It was also found that regardless of the pH of the acceptor fluids used in the release studies an increase was observed in the concentration of CTZ in CD system compared to its free form. The ability to permeate artificial biological membranes manifested by CTZ after complexation was enhanced as well. In summary, CD has significant potential to mask the bitter taste of CTZ and to counter the instability induced by oxidizing factors.     

Co-solvent modulation of the inclusion selectivity ofβ-cyclodextrin

The solubility of-CD, which is increased to 87 gL^–1 in 75% water - 25% isopropanol mixtures, does not behave in a linear fashion as a function of the water/isopropanol ratio. Application of this increased solubility to the formation of inclusion complexes between-cyclodextrin and cineole : eugenol, cineole : pinene and eugenol : pinene shows strong solvent modulation of the inclusion selectivity. The proportion of guests complexed is in inverse ratio to the compatibility of the guests in the solvent mixture.     

Reaction of γ-Sultines with Electrophilic Reagents. 1. Bromination of 3,5-Diaryl-1,2-oxathiolane 2-Oxides

The effects of the nature of the aryl substituents and the reaction conditions on the bromination of 3,5-diaryl-1,2-oxathiolane 2-oxides (-sultines) have been studied. The possible mechanisms for the bromination of the -sultines are discussed on the basis of the experimental data.     

Solubility characteristics ofβ-cyclodextrin inclusion complexes

Some inclusion complexes of-cyclodextrin (cyclomaltoheptaose) have been investigated, particularly with respect to their solubility. The mathematical characterization of the equilibrated host-guest system containing both solid and solution phases is discussed (first of all those, which contain 1:1 or 1:1 + 2:1 species) and demonstrated by different examples.     

Condensed pyridopyrimidines. 1. Synthesis of new derivatives of pyrano[3′,4′∶5,6]pyrido[2,3-d]pyrimidines

New derivatives of pyrano[3,45,6]pyrido[2,3-d]pyrimidines were synthesized from ethyl 2-amino-7,7-dimethyl-7,8-dihydro-5H-pyrano[4,3-b]pyridine-3-carboxylate.A. L. Mndzhoyan Institute of Fine Organic Chemistry, National Academy of Sciences of the Republic of Armenia, Erevan. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1239–1241, September, 1999.     

Study on inclusion interaction of hydrophilic 2-chloromandelic acid with hydroxypropyl-β-cyclodextrin

The inclusion interaction between hydroxypropyl-β-cyclodextrin (HP-β-CD) and hydrophilic 2-chloromandelic acid (CMA) was studied by ultraviolet (UV) absorption spectrophotometer. A reliable determination of the complex stoichiometry was provided by the continuous variation technique. ¹H NMR spectrum and Thermo-gravimetric/differential thermal analyzer (TG/DTA) techniques were explored to further characterize the inclusion complex, and molecular modeling was used to investigate the mechanism of inclusion interaction. The results showed that HP-β-CD reacted with R,S-CMA to form inclusion complexes, with 1:1 stoichiometry and inclusion stability constants K_R and K_S were 24 and 39 L/mol determined from UV data by the method of Benesi-Hildebrand’s. Molecular modeling confirmed experimental observation and indicated that the hydrogen bonding interaction plays an important role in the interactive inclusion between HP-β-CD and CMA. Besides, compared with the HP-β-CD, molecular modeling showed R, S-CMA interact with β-CD through different binding modes, in which Vander Waals is the main intermolecular force between β-CD and R-CMA (or S-CMA) while without obvious hydrogen bonding interaction.     

Synthesis and properties of furan derivatives. 1. Synthesis of 3,5-disubstituted Δ2-isoxazolines containing furfuryl fragments

3,5-Disubstituted ²-isoxazolines containing furan fragments have been synthesized by 1,3-dipolar cycloaddition reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 449–452, April, 1991.