Verification of Solvation Theory of Dilute to Concentrated Solutions of Some Strong 1–1 Electrolytes

Density, ultrasonic velocity and isobaric heat capacity data have been used to study solvation parameters of aqueous solutions of NaCl, NaNO₃, and KI. Using correct thermodynamic relations, quantitative solvation parameters have been determined at temperatures from 278.15 to 323.15 K: the hydration numbers h, the molar isentropic compressibilities of the solvation complexes $ \beta_{S,h} V_{h} , $ the volume V _1h , the coefficient of isentropic compressibility β _1h of water in the solvation shells of ions, and others. It has been shown that h is independent of the temperature in the range of the investigated conditions, $ \beta_{S,h} V_{h} $ is dependent both on the temperature and concentration, whereas the electrostriction compression in the vicinity of ions has a greater effect on its structure than that due to the mere change of pressure.     

Effect of Solvents on Oxidation of 1, 1′-Bi-2-naphthol

A novel biomimetic catalyst of complex Cu (p-OTs)2/ethanolamine (1 : 1 ) was used to oxidize 1, 1′-bi-2naphthol into xanthene derivatives with a relative high yield in a mixed solvents of dimethyl sulfoxide (DMSO) and CH3OH. The studies on the effect of some solvents on the yield of xanthene derivatives indicates that the yield reduces dramatically with the increase of the content of H2O in the mixed solvents of H2O and DMSO. No product can be obtained when the content of H2O is up to 70%. The cyclic voltammetric study demonstrated that the copper ion in complex Cu(p-OTs)2/ethanolamine(1:1) is reduced via a twostep one-electron reduction process from Cu (Ⅱ) to Cu in the mixture of DMSO and H2O. Water as a poor solvent in respect to the reactants probably hampered the coordination of 1, 1′-bi-2-naphthol to copper/amine complex and led to the insufficient catalytic efficiency of complex Cu(p-OTs),/ethanolamine(1:1).     

Toward the synthesis of 1′E-isomer of ent-hyptenolide

A short total synthesis of a diacetoxylated E,E-diene lactone ent-hyptenolide, was achieved involving from Phosphonate and cis-butene 1,4-diol. Brown Asymmetric allylation, Acrylation, Acetylation, Ring-closing metathesis as the key steps has been described. Moreover, the biological activity of ent-hyptenolide was evaluated on HeLa, A549, IMR32, and MDA-MB231 cancer cell lines. The ent-hyptenolide selectively and potently inhibited the growth of IMR32 cell line.     

Synthetic Studies of an Analogue of HIV-1 Protease Inhibitors of Didemnaketals:Construction of the C1-C8 Intermediate

ThedidenlnaketalsAandBhaveprovedtobesignificantinhibitorstoHIV-Iprotease'.UPtotilepresent.however,nosuccessfulsynthesishasbeenreported.Inconnectiollx'l,lthOLlrs}'ntheticstudiesoftheiranalogLles,wehavereportedasuccesslillsynthesisofthesimilarilltermediateof32.Hereinwewouldpresentanefficientprocedureforthediastereoselectivesynthesisofanotherintermediate4.Basedoiltileretrosyntheticanalysis,theintermediate4couldbesynthesizedfromllaturalI.-(-)-nlelltllollebecauseofthevaltlablechiralCSmethyl.…     

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.     

Characteristics of mass spectra of dichlorocarbene derivatives of isomeric dodecen-1-ols

The m/z of characteristic ion of the mass spectra of the dichlorocarbene derivatives of dodecen-1-ols was used as a parameter to locate the position of double bond in these isomers by a new formula.     

Association-Assisted Kinetics of Pentanol-1 and Heptanol-1 Oxyethylation: Kinetic Parameters of Reactions and Association Parameters of Alcohols in the Series Butanol-1–Heptanol-1

The kinetics of pentanol-1 and heptanol-1 oxyethylation in the absence and in the presence of solvents (dodecane, p-xylene, and 1,4-dioxane) is studied under the conditions of base catalysis at 80–150°C and the concentrations of the catalyst (the corresponding sodium alkoxide) and ethylene oxide in the starting mixture of 1 and 10^–3–10^–1 mol/l, respectively. The experimental results are adequately described by the rate law that takes into account the association of alcohol molecules via hydrogen bonds. A hypothesis is advanced that an associate consisting of n alcohol molecules acts as a kinetically independent species in this reaction. The kinetic and association parameters for alcohols in the C₄–C₇ series are compared with the published data.     

Microbiologically-assisted hemisynthesis of 1α-hydroxydrimenol

The hemisynthesis of 1α-hydroxydrimenol has been selected to illustrate a synthetic route involving an initial microbial 3β-hydroxylation of a drimenol derivative followed by a functionalization transfer to position 1α, thus generating a new potentially bioactive hydroxylated terpenic compound. Several methods have been investigated for the protection and the regeneration of the 7,8-double bond of drimenyl derivatives.     

Synthesis of the reported structure of trans-africanan-1α-ol

A trisubstituted cyclopentane chiron has been prepared by dynamic kinetic reduction of a pulegone-derived β-keto ester. This chiron served as the starting material for the synthesis of the reported structure of the tricyclic sesquiterpene trans-africanan-1α-ol. The synthetic material was not congruent with the natural product.     

Synthesis of substituted α-tetralones and substituted 1-naphthols via regioselective ring expansion of 1-acyl-1-indanol skeleton

Substituted 1-acyl-1-indanols were prepared using the corresponding readily commercially available substituted indanones as starting materials. Treatment of each 1-acyl-1-indanol derivative with sodium methoxide in hot methanol furnished a regiospecific 2-hydroxy-α-tetralone derivative, which was an α-keto rearrangement product. Each substituted 2-hydroxy-α-tetralone then underwent dehydration to afford the corresponding 1-naphthol derivative.     

Reduction of 1-Deoxy-13-oxotaxanes

Reduction of 1-deoxy-13-oxotaxanes has been studied under different reaction conditions. Some interesting reactions were reported.     

Comparative study of ionic interactions of 1 : 1 and 1 : 2 electrolytes of nitrates salts solutions with water analysed with physicochemical data

Densities (ρ), viscosities (η) and surface tension (γ) as function of the molarity of 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 for LiNO₃, NaNO₃, KNO₃, Sr(NO₃)₂, Ba(NO₃)₂ and Pb(NO₃)₂ electrolytes are reported at 32°C. Data were regressed for limiting values for solute–solvent interactions and effects of shell numbers and electronic configurations. A confidence variance of 95.5% at Gaussian distribution was noted. Densities explained ionic forces and sizes, and viscosities defined frictional forces while the surface tension focused surface energies of hydrated ions. Slopes of densities, viscosities and surface tensions explained the concentration effects on ionic interactions. Limiting densities from Li⁺ to Ba²⁺ increased with increase in sizes. Pb²⁺ smaller in size than the Ba²⁺ had lower limiting densities. The ρ ⁰ are Ba^2+?>?Sr^2+?>?Pb^2+?>?K^+?>?Na^+?>?Li⁺ with 3.24, 2.98, 4.53, 2.109, 2.257 and 2.38?×?10^3?kg?m^?3 densities of nitrate salts, respectively, in the solid state.     

Characterization of Immobilized β-N-Acetylhexosaminidase1

Abstract

The properties of fl-N -acetylhexosaminidase chemically bound to Sepharose 4B were determined and compared to those of the soluble enzyme. External diffusion effects on the kinetics of the immobilized enzyme were eliminated by assaying in a recirculation reactor with rapid flow rates. The immobilized 15-N-acety Hexosaminidase exhibited a broad pH optimum quite similar to that of the soluble enzyme. Compared to the soluble enzyme the immobilized enzyme demonstrated a markedly enhanced stability at each pH and temperature investigated. Immobilization caused an increase in both the apparent K and K., with rrm. A preliminaty account of this work was presented at the Annual Meeting of the Federation of American Societies for Experimental Biology, Atlantic City, N. J., April, 197 3.     

Characterization of Galactosyl-neoglycoalbumin~1 by MALDI-TOF-MS

It was reported there was a membrane receptor, hepatic binding protein (HBP), which resides only at the cell surface of mammalian hepatocytes, selectively bind galactose- terminated glycoprotein for transporting to hepatic lysosomes1. According to this discovery, a special analog ligand, galactosyl-neoglycoalbumin(NGA), was prepared as hepatic targeting drug carrier and hepatic screening agents. The ligand was synthesized by covalent coupling of carbohydate bifunctional reagent, 2-imino-2-et…     

Franck-Condon simulation of the A1B2→X1A1 dispersed fluorescence spectrum of fluorobenzene and its rate of the internal conversion

By using three different hybrid exchange-correlation functionals containing 20%, 35%, and 50% of exact Hartree-Fock (HF) exchange of the density functional theory and its time-dependent extension plus the Hartree-Fock and the configuration interaction of single excitation methods, equilibrium geometries, and their 30 vibrational-normal-mode frequencies of the ground S(0)((1)A(1)) and the first excited S(1)((1)B(2)) states of fluorobenzene (FB) were calculated. The dispersed fluorescence spectrum and internal conversion (IC) rate of the A(1)B(2)→X(1)A(1) transition were simulated by Franck-Condon (FC) calculations within the displaced harmonic oscillator approximation plus anharmonic and distorted corrections. The simulated spectral profile is primarily described by the Franck-Condon progression from the ring-breathing modes ν(9) and ν(10) which belong to totally symmetry modes. Anharmonic corrections simultaneously improve the intensity order of 9(1)(0) and 10(1)(0) bands and diminish 1(1)(0) transition that is fairly strong in harmonic simulations. It is concluded that the amount of Hartree-Fock exchange does impact the geometries and vibrational frequencies of FB molecule, but not the relative intensities of the transitions. It is anharmonic corrections that make the relative intensities of the transitions in good agreement with experimental results. Distorted corrections could assign most of the dominant overtones of out-of-plane nontotally symmetry modes, and the results agree well with the experimental assignments. Furthermore, it was found that the internal conversion rate is dominated by three promoting modes that are computed with lowing symmetry to C(1). By choosing dephasing width as 10 cm(-1) that is consistent with spectral simulation, we obtained the lifetimes of the A(1)B(2)→X(1)A(1) de-excitation as 11 and 19 ns, respectively, from TD(B3LYP) and HF∕CIS calculations in comparison with the experimental value 14.75 ns.     

Hyperspherical Harmonic Expansions of Potential 1／rjt of Molecular Systems

The expansion coefficientC^D｜L｜ of Coulomb potential 1/jt of molecular systems in hyperspherical harmonics is derived in detail,and the explicit expression is given.     

Promoting the Activity of Bifunctional Catalysts for Autoxidation of 1-Octanethiol

Mercaptans in petroleum products wreck the quality of finished products, so it is necessary to remove them in petroleum refining industry. Merox fixed-bed process is widely used in which mercaptans are converted by contacting feedstock with a metal phthalocyanine catalyst in the presence of air and an alkaline agent. However, use of caustic brings a spent caustic disposal problem so that novel caustic-free catalysts are highly desired to meet environment requirements1-3. It is not just simply …     

The Preparation of 1H-Pyrazole-1-carboxylic Acid, 1, 1-Dimethylethyl Esters from Dilithiated C(α), N-Hydrazones of Hydrazinecarboxylic Acid, 1, 1-Dimethylethyl Ester

C(α), N-Hydrazones of hydrazinecarboxylic acid, 1, 1-dimethylethyl ester [C(α), N-carbo-t-butoxyhydrazones] were metalated with excess lithium diisopropylamide, and the dianion-type intermediates were condensed with select aromatic esters followed by acid cyclization to substituted 1H-pyrazole-1-carboxylic acid, 1, 1-dimethylethyl esters (N-carbo-t-butoxypyrazoles).