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1.
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. 相似文献
2.
SONGJi-guo SHENPei-kang 《高等学校化学研究》2005,21(1):88-91
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). 相似文献
3.
ThedidenlnaketalsAandBhaveprovedtobesignificantinhibitorstoHIV-Iprotease'.UPtotilepresent.however,nosuccessfulsynthesishasbeenreported.Inconnectiollx'l,lthOLlrs}'ntheticstudiesoftheiranalogLles,wehavereportedasuccesslillsynthesisofthesimilarilltermediateof32.Hereinwewouldpresentanefficientprocedureforthediastereoselectivesynthesisofanotherintermediate4.Basedoiltileretrosyntheticanalysis,theintermediate4couldbesynthesizedfromllaturalI.-(-)-nlelltllollebecauseofthevaltlablechiralCSmethyl.… 相似文献
4.
Purushotham Reddy Karra 《合成通讯》2013,43(18):2333-2338
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. 相似文献
5.
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. 相似文献
6.
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. 相似文献
7.
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. 相似文献
8.
《Physics and Chemistry of Liquids》2012,50(5):617-629
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 Ba2+?>?Sr2+?>?Pb2+?>?K+?>?Na+?>?Li+ with 3.24, 2.98, 4.53, 2.109, 2.257 and 2.38?×?103?kg?m?3 densities of nitrate salts, respectively, in the solid state. 相似文献
9.
《Analytical letters》2012,45(6):501-514
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. 相似文献
10.
Chun CAI Yong WU West China School of Pharmacy Sichuan University Chengdu Guangdong Medical College Zhanjiang 《中国化学快报》2005,16(6)
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… 相似文献
11.
《Tetrahedron: Asymmetry》2001,12(14):2013-2018
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. 相似文献
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13.
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. 相似文献
14.
Te-Fang Yang Kuan-Yu Wang Hsuan-Wei Li Yang-Chan Tseng Tai-Chen Lien 《Tetrahedron letters》2012,53(5):585-588
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. 相似文献
15.
MengZHANG DaLiYIN JiYuGUO XiaoTianLIANG 《中国化学快报》2005,16(7):893-896
Reduction of 1-deoxy-13-oxotaxanes has been studied under different reaction conditions. Some interesting reactions were reported. 相似文献
16.
《Chemical physics letters》1986,126(6):558-566
The Doppler-free two-photon excitation spectrum of the qqQ branch of the 1410 vibrational band of the S1(1B2u) ← S0(1A1g) transition of benzene-d1 has been recorded using a cw single-mode dye laser coupled to an external concentric resonator. The spectrum has been analysed using a non-rigid Watson Hamiltonian. More than 200 lines with J up to 20 have been assigned and the rotational constants which best reproduce the spectrum are A1v = 0.181435, B1v = 0.169990, C1v = 0.089055 cm−1. The Ka = odd lines of the qqQ5(J) subbranch show small and quite regular perturbations of 60 ± 5 MHz which are probably due to a coupling to another vibrational state of the S1 manifold. 相似文献
17.
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. 相似文献
18.
《Chemical physics letters》1985,119(1):38-41
We present photoelectron spectra of the lowest singlet state (1E′') of sym-triazine obtained with 2 ns and 5 ps excitation sources. Comparisons of picosecond and nanosecond spectra are made at three wavelengths, corresponding to the 601, 602 and the 6011201 vibrational levels. The spectra show that rapid (</ 5 ps) relaxation to the lowest triplet state occurs subsequent to singlet excitation. Coupling of S1 levels to the T1 manifold is very inhomogeneous with intersystem crossing rates ranging from 107 s−1 to > 1011 s−1. Furthermore, for excitation at the 6011201 level we find evidence for relaxation to another excited state at rates ⩾ 1011 s−1. 相似文献
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