Solubility of Oxygen in Some 1-1, 2-1, 1-2, and 2-2 Electrolytes as a Function of Concentration at 25°C

The solubility of oxygen has been measured in a number of electrolytes [(LiCl, KCl, RbCl, CsCl, NaF, NaBr, NaI, NaNO₃, KBr, KI, KNO₃, CaCl₂, SrCl₂, BaCl₂, Li₂SO₄, K₂SO₄, Mn(NO₃)₃)] as a function of concentration at 25°C. The solubilities, mol (kg-H₂O)^–1, have been fitted to a function of the molality m (standard deviation < 3mol-kg^–1)

Theoretical Study on the Stable Structures and Aromaticities for Pnictogen Dianionic Sb4^2-, Bi4^2-, and （SbBi）2^2- Clusters

Through the theoretical calculation of structural optimization, vibrational frequencies and atomization energies with one method of density functional theory （B3LYP） and two post- Hartree-Fock approaches （MP2, CCSD（T））, several stable isomers for new three pnictogen dianionic Sb4^2-, Bi4^2-, and （SbBi）2^2- species were determined. For two homoatomic Sb4^2- and Bi4^2- species, there are three stable isomers： square （D4h）, roof-shaped （C2v-1）, and C2v-2 structure with the square isomer being the ground state. For the heteroatomic dian- ionic （SbBi）2^2- species, there are also three stable isomers： rhombus （D2h）, roof-shaped （C1）, and C2v structures with the rhombic isomer being the ground state. The calculated NICS values show that nucleus-independent chemical shifts （NICS） values of roof-shaped isomers for Sb4^2-, Bi4^2-, and （SbBi）2^2- species are all negative, consequently indicating that these roof-shaped isomers possess aromaticities. NICS values for the planar ring isomers are all positive, suggesting that these three planar ring isomers have antiaromatic characters. The aromaticity for the two stable roof-shaped and square isomers are preliminarily explained and discussed with MO analysis.     

Enantioselective preparation of (2R,3R)-(+)- and (2S,3S)-(−)-2,3-epoxy-2-methylbutanoic acids and some derivatives

(2R,3R)-(+)- and (2S,3S)-(−)-2,3-epoxy-2-methylbutanoic acids (epoxyangelic acids) were prepared from (Z)-2-methyl-2-butenoic acid using the Sharpless asymmetric epoxidation method in combination with the use of (−)- and (+)-menthol as chiral auxiliaries. Both substances, obtained in high enantiomeric excess, were characterized by spectroscopic and optical activity data. Their absolute configuration was determined by correlation with (R)-(+)-2-methyl-1,2-butanediol.     

Design,Synthesis and Biological Activity of Ethyl 2-（N-Substituted-arylsulfonamido）-2-oxoacetate

Thirteen new ethyl 2-（N-substituted-arylsulfonamido）-2-oxoacetates（3a-3m）, based on the structure of Ketol-acid reductoisomerase（KARI） inhibitor IpOHA, were designed and synthesized. Their structures were established on the basis of ^1H NMR, IR, MS, and elemental analyses. The bioassay result reveals that the structural changes from hydroxyl group on the N atom of IpOHA to arylsulfonyl groups does not enhance the inhibitory activity of the compounds to KARI in vitro. Compounds 3c, 3h, 3k, and 3m are more effective than IpOHA against the monocotyledonous bamygrass at 100 ug/mL in herbicidal tests.     

NHC-Activations on α-, β-, γ-, and Beyond

Over the recent decades, due to the special electronic characteristics and diverse reactivities, N-heterocyclic carbene (NHC) has received significant interest in organocatalyzed reactions. The formation of Breslow intermediates by NHC can convert into acyl anion equivalent, enolates, homoenolate, acyl azolium, and vinyl enolate etc., and the cycloaddition reactions of these species has attracted lots of attention. In this review, we focus on the summry of the development of NHC-activation of carbonyl carbon (or imine carbon) in situ, α-, β-, γ-, and beyond, and the cycloaddition reaction of these species.     

Synthesis, Crystal and Molecular Structure and Biological Activity of Dimethyl Trans-3-（2- bromophenyl）-2-methylisoxazolidine-4,5-dicarboxylate

The compound of dimethyl trans-3-(2-bromophenyl)-2-methylisoxazolidine-4,5-dicarboxylate has been synthesized and characterized by IR, 1H-NMR, 13C-NMR, 2D-NMR (COSY, NOESY, HMQC, HMBC) and UV-vis. spectroscopy techniques and single-crystal X-ray diffraction (XRD). The biological activities of the title compound have been investigated in detail. The new compound crystallizes in monoclinic, space group C2/c with a = 26.9263(10), b = 7.0970(2), c = 19.8554(7) ?, and β = 126.630(2). In addition to the single crystal structure, the molecular geometry, vibrational frequencies, chemical shifts, molecular electrostatic potential and frontier molecular orbital analysis of the title compound in the ground state have been calculated by Density Functional Theory (DFT) method.     

Separation and Determination of Cobalt, Rhodium,Nickel and Iridium with 2-(6-Methyl-2-Benzothiazolylazo)-5-Diethylamino Phenol by HPLC

The synthesis and spectrophotometric properties of 2-(6-methyl-2-benzothiazolylazo)-5-diethylamino phenol (MBTAE), and the use of it as a precolumn derivatizing reagent to separate Co(Ⅱ), Ni(Ⅱ), Rh(Ⅲ) and Ir( Ⅳ) complexes by HPLC are discussed. When the mobile phase consists of methanol/water(90/10 Ⅴ/Ⅴ), acetate buffer with pH 4. 0 and 5×10-5 mol/L EDTA solution, the four complexes Can be separated within 9 min on ODS column. The detection limits (20 μL sample size) are 0. 059 ppb, 0. 062 ppb, 0. 053 ppb and 0. 049 ppb for Co(Ⅱ) , Rh(Ⅲ), Ni(Ⅱ) and lr(Ⅳ) respectively at a signal-to-noise ratio of 3.     

Synthesis of 2-(hydroxyphenylamino)- and 2-(aminophenylamino)-4-methylquinolines and N,N′-bis(4-methylquinolin-2-yl)benzenediamines

2-(Hydroxyphenylamino)- and 2-(aminophenylamino)-4-methylquinolines and N,N′-bis(4-methylquinolin-2-yl)benzenediamines were synthesized by reactions of 2-chloro-4-methylquinolines with o-, m-, and p-aminophenols and o-, m-, and p-phenylenediamines.     

Chemical and enzymatic synthesis of 2-(2-carbamoylethyl)- and 2-(2-carboxyethyl)aziridines and their conversion into δ-lactams and γ-lactones

Treatment of 1-arylmethyl-2-(2-cyanoethyl)aziridines with a nitrile hydratase afforded the corresponding 2-(2-carbamoylethyl)aziridines, which underwent rearrangement into 5-hydroxypiperidin-2-ones upon heating under microwave irradiation. In addition, treatment of 2-(2-cyanoethyl)aziridines with a nitrilase selectively afforded 5-hydroxypiperidin-2-ones in good yields. On the other hand, chemical hydrolysis of 2-(2-cyanoethyl)aziridines using KOH in EtOH/H(2)O furnished the corresponding potassium 3-(aziridin-2-yl)propanoates, which, upon acidification with acetic acid, smoothly rearranged into 4-(aminomethyl)butyrolactones.     

Spectral and electrochemical properties of mono-, bi-, and tetranuclear cyclopalladized complexes based on 2-(2-thienyl)pyridine and 2-phenylpyridine with pyridine and 4,4′-bipyridyl

Mono-, bi-, and tetranuclear cyclopalladized complexes based on 2-(2-thienyl)pyridine and 2-phenylpyridine with pyridine and 4,4′-bipyridyl were prepared and characterized by the methods of ¹H NMR, electron absorption and emission spectroscopy, and also by the voltammetry method. The values of the coordination-induced shifts of proton in the ligands of the complexes were determined; the upfield displacement of chemical shifts of protons of the cyclopalladized ligand nearest to the metal was assigned to the anisotropic action of a ring current of the pyridine rings orthogonal to the coordination plane in 4,4′-bipyridyl and pyridine. Long-wave absorption bands of the complexes were assigned to the spin-allowed optical d-π charge-transfer transitions, and the bands of the low-temperature phosphorescence, to the intraligand π-π_NyyC^* transitions. Three waves of the reduction of the complexes were assigned to the ligand-centered processes of successive electron transfer on π* orbitals preferentially localized on coordinated pyridine and cyclopalladized ligands.     

Hydrogen Bonds, Tautomers, and Conformation in 2-Hydroxyphenyl 2-hydroxy-2-(β-naphthyl)vinyl Ketone

Single crystal X-ray diffraction and IR spectroscopy have been used to study the conformation of 2-hydroxyphenyl 2-hydroxy-2-(-naphthyl)vinyl ketone in solid state. It was found that one of the two possible enol tautomeric forms is stabilized in the crystal. The 1-hydroxy-3-oxo-1,3-propenylene moiety, O=C—CH=C—OH, shows a strong intramolecular H bond with a definite character of reasonance-assisted hydrogen bond in spite of being in competition with ring intermolecular hydrogen bonds. The comparison of the present results with solution NMR data indicates that the molecular geometry in solid state and in solution are similar.     

Synthetic Approaches to α-, β-, γ-, and δ-Lycoranes

Lycorane is a pentacyclic core presented in alkaloids isolated from the Amaryllidaceae family of herbaceous flowering plants. Members of this class of natural products have shown to display important biological properties including analgesic, antiviral, and antiproliferative activities. This review presents the known synthetic routes toward α-, β-, γ-, and δ-lycoranes. α-(19 routes), β-(10 routes), γ-(38 routes), and δ-(6 routes).     

Synthesis and characterization of α-, β-, and γ-Ga2o3 prepared from aqueous solutions by controlled precipitation

α, β and γ-Ga₂O₃ have been successfully obtained in an easily scalable synthesis using aqueous solution of gallium nitrate and sodium carbonate as starting materials without any surfactant and additive. α and β-Ga₂O₃ were obtained by calcination at 350 and 700 °С, respectively, of α-GaOOH, prepared by controlled precipitation at constant pH 6 and T = 55 °С, with 24 h of aging. Aging was necessary to fully convert the initially preciptated gel into a well-crystalline and phase-pure material. γ-Ga₂O₃ was obtained after calcination at 500 °С of gallia gel, synthesized at constant pH 4 and T = 25 °С, without aging. These three polymorphs have a for gallia relatively high surface area: 55 m²/g (α-Ga₂O₃), 23 m²/g (β-Ga₂O₃) and 116 m²/g (γ-Ga₂O₃). The combination of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), nitrogen physisorption and thermogravimetry (TG) was employed to characterize the samples and their formation.     

Synthesis and Molecular Structure of 5, 5-Dimethyl-2- (4' -methoxy)phenyl-1, 3, 2- thiazaphospholidine-4-thione 2-sulfide

1 INTRODUCTION In our previous study [1], we found that 1, 3, 2-thiazaphospholidine-4-thione 2-sulfide deriva- tives possessed various bioactivities such as herbicidal, antiviral, fungicidal activity, Which the is strongly held our interest to exploit new method for the synthesis of such phosphorohe- terocycles and investigate their biological activities. Different method for the preparation of 1, 3, 2-thiazaphospholidine-4-thione (one) 2-sulfides have been reported [2~4]. According to …     

Synthesis,reactions, and antimicrobial activity of 2-cyano-N′-(4-(2-oxo-2-phenylethoxy)benzylidene)acetohydrazide derivatives

Knӧvenagel condensation of the starting 2-cyano-N′-(4-(2-oxo-2-phenylethoxy)-benzylidene)acetohydrazide with different aromatic aldehydes produced the comparable arylidenes derivatives. Else way, 2-cyano-N′-(4-(2-oxo-2-phenylethoxy)-benzylidene)-acetohydrazide condensed with o-hydroxybenzaldehydes affording the respective chromenes which latter underwent acid hydrolysis giving the oxo-chromenes analogues. Moreover, the reaction of 2-cyano-N′-(4-(2-oxo-2-phenylethoxy)benzylidene)acetohydrazide with istain yielded the respective indeno[2,1-b]furan derivative that was converted to its oxo-analogue through acid hydrolysis. The treatment of 2-cyano-N′-(4-(2-oxo-2-phenylethoxy)benzylidene)acetohydrazide with α-halocompounds produced the relevant thiazoles. The enamine 2-cyano-3-(dimethylamino)-N′-(4-(2-oxo-2-phenylethoxy)benzylidene)acrylohydrazide underwent nucleophilic substitution reaction with guanidine hydrochloride followed by heterocyclization to get the relative aminopyrimidine. Contrarily, the reaction with various 4-arylazo-3,5-diaminopyrazoles provided the relative pyrazolo[1,5-a]pyrimidines. The antimicrobial investigation was carried out for some of the newly synthesized compounds using agar well diffusion method.     

Synthesis,spectroscopic characterization,thermal, and photostability studies of 2-(2′-hydroxy-5′-phenyl)-5-aminobenzotriazole complexes

Three Mn(II), Co(II), and Cu(II) new transition metal complexes of the fluorescence dye: 2-(2′-hydroxy-5′-phenyl)-5-aminobenzotriazole/PBT derived from o-aminophenol and m-phenylenediamine have been synthesized. The structural interpretations were confirmed from elemental analyses, magnetic susceptibility and molar conductivity, as well as from mass, IR, UV–Vis spectral studies. From the analytical, spectroscopic, and thermal data, the stoichiometry of the mentioned complexes was found to be 1:2 (metal:ligand). The molar conductance data revealed that all the metal chelates are non-electrolytes and the chloride ions exist inside the coordination sphere. The thermal stabilities of these complexes were studied by thermogravimetric (TG/DTG) and the decomposition steps of these three complexes are investigated. The kinetic parameters such as the energy of activation (E*), pre-exponential factor (A), activation entropy (ΔS*), activation enthalpy (ΔH*), and free energy of activation (ΔG*) have been reported. Photostability of phenyl benzotriazole as fluorescence dye and their metal complexes doped in polymethyl methacrylate/PMMA were exposed to UV–Vis radiation and the change in the absorption spectra was achieved at different times during irradiation period.     

Syntheses,structures, and properties of transition metal complexes with 2-( n -pyridyl)benzimidazole ( n = 2, 3, and 4)

Three pyridylbenzimidazoles (2-PBIM, 3-PBIM, and 4-PBIM) have been prepared (2-PBIM: 2-(2-pyridyl)-benzimidazole, 3-PBIM: 2-(3-pyridyl)-benzimidazole, 4-PBIM: 2-(4-pyridyl)-benzimidazole). Reactions of several transition metals (Cd²⁺, Cu²⁺, Fe²⁺) with the three ligands gave four new coordination complexes, [(Cd)₂(2-PBIM)₂(CH₃COO)₄] (1), [Cu(3-PBIM)₂(CH₃COO)₂]?·?2H₂O (2), [Cu(4-PBIM)₂(CH₃COO)₂(H₂O)]?·?H₂O (3), and [Fe(4-PBIM)₂(Cl)₂(H₂O)₂] (4), respectively. These four complexes have been characterized by X-ray crystallography, IR spectroscopy, and UV absorption spectroscopy. Thermogravimetric properties of 2 and 4 were also measured. X-ray crystallographic studies reveal that these four complexes are very different, although the ligands are similar in structure. The role of hydrogen-bonding and π–π interactions in extending dimensionality of simple complexes has been discussed.     

5-芳酰氨基-2-苯基-2H-1, 2, 4-噻二唑-3-酮的合成

用1-芳酰基-5-苯基-2-硫代双脲与溴进行氧化成环反应制备了九个新的5-芳酰氨基-2-苯基-2H-1, 2, 4-噻二唑-3-酮, 相应的1-芳酰基-5-苯基-2-硫代双脲可以通过苯基脲与酰基异硫氰酸酯加成制得。