Volumetric Properties of Sodium Nitrobenzoate in <Emphasis Type="Italic">N</Emphasis>, <Emphasis Type="Italic">N</Emphasis>-Dimethylformamide–Water Mixtures at 298.15 K

Densities of sodium nitrobenzoate (o-, m-, p-) have been measured in dimethylformamide (DMF)–water mixtures at 298.15 K with an oscillating-tube densimeter. From these densities, apparent molar volumes of sodium nitrobenzoate in DMF–H₂O-mixtures have been calculated and partial molar volumes at infinite dilution have been evaluated. Substituent and solvent effects on the transfer volumes of each isomer from water to DMF–H₂O-mixed solvents have also been obtained. The results are explained in terms of solvent–solvent and solute–solvent interactions.     

Volumetric Properties for Binary and Ternary Mixtures Containing Benzyl Alcohol,Ethyl Butyrate and Diethyl Malonate at <Emphasis Type="Italic">T</Emphasis> = (293.15–313.15) K and <Emphasis Type="Italic">p</Emphasis> = 0.087 MPa

The densities of binary and ternary mixtures of benzyl alcohol + ethyl butyrate and/or diethyl malonate were measured at T = (293.15–313.15) K and p = 0.087 MPa. From these data, the excess molar volumes, partial molar volumes, excess partial molar volumes, partial molar volumes at infinite dilution, thermal expansion coefficients and their excess values were calculated. The Redlich–Kister equations were fitted to the excess molar volumes data. The results show that the excess molar volumes for all considered binary and ternary systems are negative and decrease with increasing temperature. The same behavior was observed for the excess thermal expansion coefficients. Data for excess volumes in ternary system were fitted with the Nagata–Tamura and Cibulka models for which the Cibulka equation showed better fitting. The intermolecular interactions between molecules in these mixtures are discussed and explained based on these experimental data.     

1,3-Diamino-2-Hydroxypropane-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-Tetraacetic Acid: Crystal and Molecular Structures

The synthesis, IR spectroscopic study, and X-ray diffraction analysis (CIF file CCDC no. 1574078) are carried out for 1,3-diamino-2-hydroxypropane-N,N,N′,N′-tetraacetic acid (I). The structural units of a crystal of compound I are (H_4.5HPdta)^0.5– anions, (H_5.5HPdta)^0.5+ cations, and molecules of water of crystallization joined by a branched network of hydrogen bonds: strong intermolecular O–H…O and intramolecular N–H…O bonds.     

<Emphasis Type="Italic">N</Emphasis>′-tetrazolylmethoxyl derivatives of <Emphasis Type="Italic">N</Emphasis>-methyldiazene <Emphasis Type="Italic">N</Emphasis>-oxides

A preparation method was developed for previously unknown tetrazole derivatives containing in the 1, 2, and/or 5 positions of the tetrazole ring N-methyldiazene-N-oxide-N′-oxymethyl groups.     

Directed Aminomethylation of Pyrrole,Indole, and Carbazole with <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>-Tetramethylmethanediamine

Catalytic aminomethylation of pyrrole and indole with N,N,N′,N′-tetramethylmethanediamine in the presence of 5 mol % of ZrOCl₂·8H₂O proceeds selectively at the positions 2, 5 of pyrrole and 1, 3 of indole. Carbazole under the same conditions affords 3-formyl-9-aminomethyl derivative. The reaction in the presence of 5 mol % of K₂CO₃ occurs as monoaminomethylation: for pyrrole at the position 2, for indole at the position 3, and for carbazole at the nitrogen atom of the substrate. Water-soluble 1,1′-(1H-pyrrole-2,5-diyl)bis(N,N-dimethylmethanamine) exhibits a fungistatic activity with respect to phytopathogenic fungi Rhizoctonia solani.     

Spectroscopic and electrical characterization of <Emphasis Type="Italic">α</Emphasis>,<Emphasis Type="Italic">γ</Emphasis>-bisdiphenylene-<Emphasis Type="Italic">β</Emphasis>-phenylallyl radical as an organic semiconductor

The semiconductor properties of the earliest known stable radical, α,γ-bisdiphenylene-β-phenylallyl radical (Koelsch radical, 1^?) were assessed using spectroscopic and electrical techniques. This radical undergoes reversible redox processes, and it has low redox potentials. In addition, 1^? possesses long wavelength absorption bands, owing to the existence of a singly-occupied molecular orbital whose energy level lies between those of the HOMO and LUMO. A spin-coated thin-film of 1^? displays photocurrent and an electron mobility of 6.3 × 10^?7 cm² V^?1 s^?1 on a trially-fabricated organic field effect transistor.     

Complex formation of magnesium and calcium ions with trimethylenediamine-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>’,<Emphasis Type="Italic">N</Emphasis>’-tetraacetic acid

Stability constants and heat effects of the formation reactions of magnesium and calcium trimethylenediaminetetraacetates at 298.15 K and ionic strength of 0.1, 0.5, and 1.0 (mol/L KNO₃) have been determined by means of potentiometry and calorimetry. Standard thermodynamic parameters (log K⁰, Δ_rG⁰, Δ_rH⁰, and Δ_rS⁰) of the studied equilibriums have been determined.     

Thermochemistry of С<Subscript>60</Subscript> fullerene solutions in benzene,toluene, <Emphasis Type="Italic">о</Emphasis>-xylene,and <Emphasis Type="Italic">о</Emphasis>-dichlorobenzene at 298.15 K

The enthalpies of dissolution of С₆₀ in benzene, toluene, о-xylene and о-dichlorobenzene are measured in a sealed high-sensitivity calorimeter at 298.15 K and at different concentrations of the solute. The standard enthalpies of dissolution of С₆₀ in these solvents are determined.     

Expression of a Glucose-tolerant β-glucosidase from <Emphasis Type="Italic">Humicola grisea</Emphasis> var. <Emphasis Type="Italic">thermoidea</Emphasis> in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

A β-glucosidase gene (bgl4) from Humicola grisea var thermoidea was successfully expressed in Saccharomyces cerevisiae. The recombinant protein (BGL4 ^Sc ) was initially detected associated with yeast cells and later in the culture medium. BGL4 ^Sc showed optimal pH and temperature of 6.0 and 40 °C, respectively, and an apparent molecular mass of 57 kDa. The enzyme showed activity against cellobiose and synthetic substrates, and was inhibited more than 80% by Fe²⁺, Cu²⁺, Zn²⁺, and Al³⁺. Using p-nitrophenyl-β-d-glucopyranoside (pNPG) as substrate, BGL4 ^Sc presented a V _max of 6.72 μmol min⁻¹ mg total protein⁻¹ and a K _m of 0.16 mM under optimal conditions. Most important, BGL4 ^Sc is resistant to inhibition by glucose and the calculated K _i value for this sugar is 70 mM. This feature prompts BLG4 ^Sc as an ideal enzyme to be used in the saccharification process of lignocellulosic materials for ethanol production.     

<Emphasis Type="Italic">β</Emphasis>-Chloro-<Emphasis Type="Italic">α</Emphasis>,<Emphasis Type="Italic">β</Emphasis>-unsaturated carbonyls as convenient precursors of highly substituted benzenes

The Diels–Alder reactions of three β-chloro-α,β-unsaturated carbonyl compounds 1–3 with different dienes were carried out to afford highly functionalized cyclohexenes 4–9, bearing quaternary centers, in good yields. These cycloadducts (CAs) undergo dehydrochlorination with subsequent aromatization in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene DBU to produce new substituted benzenes 11–14. Compound 10 is the product of lactonization and removal of an HCl molecule from compound 7. All products were characterized by NMR, IR, elementary analysis and some of them by MS. Structure assignments of isomers were carried out on the basis of NMR chemical shifts and coupling constants using 1D, 2D and heteronOe NMR techniques.     

Synthesis of 20<Emphasis Type="Italic">S</Emphasis>-protopanaxadiol <Emphasis Type="Italic">β</Emphasis>-D-galactopyranosides

20S-Protopanaxadiol (3β,12β,20S-trihydroxydammar-24-ene) 3-, 12-, and 20-O-β-D-galactopyranosides were synthesized for the first time. Condensation of 12β-acetoxy-3β,20S-dihydroxydammar-24-ene (1) and 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosylbromide (α-acetobromogalactose) (2) under Koenigs–Knorr conditions with subsequent removal of the protecting groups resulted in regio- and stereoselective formation of 20S-protopanaxadiol 3-O-β-D-galactopyranoside, an analog of the natural ginsenoside Rh₂. Glycosylation of 12β,20S-dihydroxydammar-24-en-3-one (5) by 2 with subsequent treatment of the reaction products with NaBH₄ in isopropanol and deacetylation with NaOMe gave 20S-protopanaxadiol 12- and 20-O-β-Dgalactopyranosides.     

Phase Diagrams of the <Emphasis Type="Italic">n</Emphasis>-Decane–<Emphasis Type="Italic">n</Emphasis>-Hexadecane–Cyclododecane, <Emphasis Type="Italic">n</Emphasis>-Decane–Cyclododecane,and <Emphasis Type="Italic">n</Emphasis>-Hexadecane–Cyclododecane Systems

The n-decane–n-hexadecane–cyclododecane, n-decane–cyclododecane, and n-hexadecane–cyclododecane systems are studied by means of low-temperature differential thermal analysis using a differential scanning heat flow calorimeter. It is noted that all studied systems belong to the eutectic type. It is concluded that in the n-decane–n-hexadecane–cyclododecane system, the eutectic composition contains 85.0 wt % n-С₁₀Н₂₂, 4.0 wt % n-С₁₆Н₃₄, and 11.0 wt % С₁₂Н₂₄. It has a melting point of ?35.0°C.     

Thermophysical properties of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimеthylacetamide mixtures with <Emphasis Type="Italic">n</Emphasis>-butanol

The refraction, dielectric, viscosity, density, data of the binary mixtures of N,N-dimethylacetamide (DMA) with n-butanol at 308.15 and 313.15 K. The measured parameters used to obtain derived properties like Bruggeman factor, molar refraction and excess static dielectric constant, excess inverse relaxation time, excess molar volume and excess viscosity, excess molar refraction. The variation in magnitude with composition and temperature of these quantities has been used to discuss the type, strength and nature of binary interactions. Results confirm that there are strong hydrogen-bond interactions between unlike molecules of DMA+ n-butanol mixtures and that 1: 1 complexes are formed and strength of intermolecular interaction increases with temperature.     

Computer models of eutectic-type <Emphasis Type="Italic">T</Emphasis>–<Emphasis Type="Italic">x</Emphasis>–<Emphasis Type="Italic">y</Emphasis> diagrams with allotropy

Using the eutectic-type T–x–y diagram as an example, it can be represented the analysis of its geometrical construction dependence on the temperature of a component two polymorphous modifications which participate in mono- and invariant metatectic and invariant eutectic (eutectoid) transformations above or below (and within) binary eutectics temperature intervals and below a ternary eutectic temperature. Computer models for considered phase diagrams have been designed. Such models help to solve applied tasks like visualization, isopleths and isothermal sections decoding, mass balances calculation and evaluation of phase and conglomerate concentration in microstructure.     

An efficient synthesis of <Emphasis Type="Italic">β</Emphasis>-methoxycarbonyl-<Emphasis Type="Italic">γ</Emphasis>-butyrolactones

β-Methoxycarbonyl-γ-butyrolactones bearing a γ-aromatic substituent were prepared via copper-catalyzed reductive aldol addition/lactonization domino reactions of ketones with α,β-unsaturated dicarboxylate esters and a silane under ambient temperature. The reaction has advantage of using readily available reagents, mild conditions and high efficiency.     

Specific Refractive Index Increment (∂<Emphasis Type="Italic">n</Emphasis>/∂<Emphasis Type="Italic">c</Emphasis>) of Polymers at 660 nm and 690 nm

The specific refractive index increment (?n/?c) is an essential datum for the accurate quantitation of molar mass averages and distributions (inter alia) of macromolecules when refractometry, static light scattering, and/or viscometry detection are coupled on-line to size-based separation techniques. The latter include methods such as size-exclusion and hydrodynamic chromatography, and asymmetric and hollow-fiber flow field-flow fractionation. The ?n/?c is also needed for accurate determination of the weight-average molar mass of polymers by off-line, batch-mode multi-angle static light scattering. However, not only does ?n/?c differ among chemical species, it also depends on experimental conditions such as solvent, temperature, and wavelength. For the last 17 years, the author’s laboratories have measured the ?n/?c of a variety of natural and synthetic polymers, at both 690 nm and, more recently, 660 nm, under a variety of solvent and temperature conditions. In all cases, this has been done by off-line, batch-mode differential refractometry, not by assuming 100% analyte column recovery and 100% accurate peak integration. Results of these determinations are presented here, along with the relevant experimental data.     

10<Emphasis Type="Italic">α</Emphasis>-Hydroxy-<Emphasis Type="Italic">β</Emphasis>-isomorphine,a by-product of the synthesis of 10<Emphasis Type="Italic">α</Emphasis>-hydroxymorphine

Abstract  A new compound was isolated from the reaction mixture after O-demethylation of 6-O-acetyl-10α-acetoxycodeine with boron tribromide. The structure of this compound, 10α-hydroxy-β-isomorphine, was elucidated by spectral data, and its spatial arrangement was deduced from an NOE experiment. Capillary zone electrophoresis was used for separation of morphine and its 10-hydroxy analogues. Graphical abstract        

Volumetric Properties for Binary Mixtures of Nonane + Decane at Temperatures from <Emphasis Type="Italic">T</Emphasis>=283.15 to 353.15 K and at <Emphasis Type="Italic">p</Emphasis>=0.7 atm

Densities of the binary mixture of nonane with decane were measured at temperatures from 283.15 to 353.15 K at atmospheric pressure (0.7 atm). Measurements have been made over the full range of compositions and for the pure compounds by using a vibrating-tube densimeter (VTD). Excess molar volumes have been obtained from these experimental results and were fitted to a Redlich–Kister type expansion. The excess molar volumes exhibit small positive and small negative deviations from ideal behavior in the temperature interval studied. Partial molar volumes and partial molar volumes at infinite dilution have been determined for each component.     

Thermodynamics of complex formation in mixed solvents <Emphasis Type="Italic">K</Emphasis> and Δ<Emphasis Type="Italic">H</Emphasis> for the formation reaction of [Gly18C6] at 298.15 K

The influence of H₂O–EtOH and H₂O–Acetone mixed solvents at various compositions on the thermodynamics of complex formation reaction between crown ether 18-crown-6 (18C6) and glycine (Gly) was studied. The standard thermodynamic parameters of the complex [Gly18C6] (log K°, Δ_r H°, Δ_r S°) were calculated from thermochemical data at 298.15 K obtained by titration calorimetry. The complex stability and its formation enthalpy increase with increasing the non aqueous component concentration in both mixed solvents. The thermodynamic data were discussed on the basis of the solvation thermodynamic approach and the solvation contributions of the reagents and of the complex to the complex stability were analyzed.