Synthesis of <Emphasis Type="Italic">α</Emphasis>-chloropyridine derivatives of <Emphasis Type="Italic">γ</Emphasis>-aminobutyric acid

The sodium salt of N-(6-chloronicotinoyl)-γ-aminobutyric acid, a structural analog of the known nootropic and vasidilating drug picamilon, was synthesized via Schotten–Baumann acylation of γ-aminobutyric acid with 6-chloronicotinoyl chloride and subsequent neutralization of the N-(6-chloronicotinoyl)-γ-aminobutyric acid that was obtained in >60% yield.     

<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.     

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.     

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.     

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        

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.     

Influence of the force interaction on accumulation of macroscopic correlations in elementary reaction <Emphasis Type="Italic">A</Emphasis> + <Emphasis Type="Italic">B</Emphasis> → <Emphasis Type="Italic">C</Emphasis>

The applicability of the Encounter Theory (ET) (the prototype of the Collision Theory) concepts for widely occurring diffusion assisted irreversible bulk reaction A + B →C (for example, radical reaction) in dilute solutions taking account of initial microscopic correlations and force interactions between reactants has been treated theoretically with modern many-particle method for the derivation of non-Markovian binary kinetic equations. The method shows that taking into consideration initial correlations and force interactions leads to the redefinition of the Markovian rate constant only in the expressions derived earlier. Thus, just as in the reaction A + A →C and the reaction A + B →C neglecting force and initial correlations, the Modified Encounter Theory (MET), when reduced to equations of a Regular Form, both extends the time applicability range of ET homogeneous rate equation, and yields the inhomogeneous equation of the Generalized Encounter Theory (GET). It reveals macroscopic correlations induced by the encounters in the reservoir of free walks in full agreement with physical considerations. Time accumulation of macroscopic correlations obeys the same time law as in the previously considered case neglecting force interactions. Just the rate of the process will change, according to traditional redefinition of the steady-state constant of the reaction.     

Effect of Temperature on the Volumetric Properties of <Emphasis Type="Italic">α</Emphasis>,<Emphasis Type="Italic">ω</Emphasis>-Amino Acids in Dilute Aqueous Solutions

The partial molar volume at infinite dilution of aqueous solutions of 3-aminopropanoic acid, 4-aminobutanoic acid, 5-aminopentanoic acid and 6-aminohexanoic acid were determined at T=(293.15,298.15,303.15 and 308.15 K) from density measurements. The thermodynamic behavior of the aqueous α,ω-amino acid solutions is compared with that reported for α-amino acids in water. The interaction volume is calculated and the influence of charged and uncharged groups of the amino acids is discussed in terms of solute–solvent interactions.     

Study of<Emphasis Type="Italic"> β</Emphasis>–<Emphasis Type="Italic">α</Emphasis> recrystallization of the polypropylene

The crystalline modifications and of polypropylene (PP) were studied by using polarized light microscopy (PLM), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC). Typically crystals surrounded by spherulites were observed at low temperature. With increasing temperature the crystals melted and a new crystal appeared. More interestingly, the melting temperature of the new crystal was about 5 ° higher than that of spherulites originally present in the sample formed isothermally. It was assumed that this new crystal was the recrystalline crystal. This assumption was supported by the DSC results. Furthermore, the crystallization kinetics of the PP used was studied on the basis of the traditional Avrami analysis. As a result, the Avrami exponents of crystallization temperature from 120 to 130 °C ranged between 4.21 and 3.60, indicating that the crystallization mechanism of PP order melt was spherulitic growth and random nucleation.     

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.     

<Emphasis Type="Italic">iso</Emphasis>-<Emphasis Type="Italic">α</Emphasis>-Cyclopiazonic acid,a new natural product isolated from the marine-derived fungus <Emphasis Type="Italic">Aspergillus flavus</Emphasis> C-F-3

A new natural product, iso-α-cyclopiazonic acid (1), together with its isomer α-cyclopiazonic acid (2); three mycotoxins: aflatoxin B₁ (AFB₁) (3), aflatoxin Q₁ (AFQ₁) (4), and O-methylsterigmatocystin (OMST) (5); two diketopiperazine alkaloids: ditryptophenaline (6) and 3-[(1H-indol-3-yl)methyl]-6-benzylpiperazine-2,5-dione (7), were isolated from the marine-derived fungus Aspergillus flavus. Their structures were determined by analysis of spectroscopic data. The cytotoxicities of compounds 1 and 2 were studied using HL-60, MOLT-4, A-549, and BEL-7402 cell lines.     

Characterization of ethyl chloroformate derivative of <Emphasis Type="Italic">β</Emphasis>-methylamino-<Emphasis Type="SmallCaps">l</Emphasis>-alanine

Beta-methylamino-L-alanine (BMAA) is a neurotoxic amino acid that can be produced by cyanobacteria in aqueous environments. To analyze this compound by gas chromatography/mass spectrometry (GC/MS), BMAA must be derivatized to a nonpolar, volatile compound. This can be accomplished by reacting BMAA with ethyl chloroformate. While carrying out electron ionization (EI) mass spectrometric analysis on the (13)C-labeled derivative, it was discovered that the formation of an ion with a peak at m/z 245.12 is the result of [CH(3)CH(2)O.] loss from the amino groups resulting from alpha-cleavage. This differs from previous reports that attributed this peak to alpha-cleavage of the carboxylic ester portion of the BMAA derivative. This finding is important for understanding BMAA derivative mass spectrometric fragmentation patterns and ultimately to properly identifying and quantifying BMAA. Fragmentation pathways for the formation of other major peaks observed in the EI mass spectra are also proposed.     

Characteristics of the hydrogen bond and the structure of Н-complexes of <Emphasis Type="Italic">p</Emphasis>-n-propyloxybenzoic acid and <Emphasis Type="Italic">p</Emphasis>-n-propyloxy-<Emphasis Type="Italic">p</Emphasis>′-cyanobiphenyl

The conformational properties of p-n-propyloxybenzoic acid and p-n-propyloxy-p′-cyanobiphenyl molecules, which can exhibit liquid crystalline properties in the formation of Н-complexes, are studied (DFT/B3LYP)/cc-pVTZ method). It is found that a molecule of p-n-propyloxybenzoic acid has 16 conformers that can be divided into four groups with respect to relative energies (0 kcal/mol, 1.6 kcal/mol, 6.5 kcal/mol, and 8.1 kcal/mol), and a molecule of p-n-propyloxy-p′-cyanobiphenyl has six conformers with relative energies of 0 kcal/mol (two conformers, φ(С_Ph–O–C–C)=180°) and 1.6 kcal/mol (four conformers, φ(С_Ph–O–C–C)=64.4°). In all conformers of the 3-AOCB molecule, phenyl rings are turned at 35° relative to each other. A conformation with the planar arrangement of two rings has a higher energy by 1.5 kcal/mol. Barriers to the internal rotation of different groups are determined and it is established that the structural nonrigidity of the molecules is mainly due to the possible rotation of the–C₂Н₅ moiety about the C–C bond. It is shown that with increasing temperature the vibrational amplitudes of the OC₃H₇ substituent, which enhance the probabilities of transitions between the conformers, become appreciably larger. It is found that p-n-propyloxybenzoic acid and p-n-propyloxy-p′-cyanobiphenyl can form Н-complexes with the medium hydrogen bond. Two types of the structural organization of Н-complexes are considered: linear and angular. The similarity of energies of Н-complexes with different structures (NBO analysis) can be the reason for the occurrence of two liquid crystalline subphases of p-n-propyloxybenzoic acid and p-n-propyloxy-p′-cyanobiphenyl system.     

<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.     

Characterization of the raw essential oil eugenol extracted from <Emphasis Type="Italic">Syzygium</Emphasis> <Emphasis Type="Italic">aromaticum</Emphasis> L.

Eugenol is the main volatile compound extracted oil from clove bud, Syzygium aromaticum L., and used in traditional medicine, as a bactericide, fungicide, anesthetic, and others. Its extraction was performed using hydrodistillation which is the most common extraction technique. Its components and thermal behavior were evaluated using gas chromatography (GC) and differential scanning calorimetry (DSC), which provide a better characterization of these natural compounds. This extracted product was compared to the standard eugenol results. The GC results suggested ~90% eugenol was found in the total extracted oil, and some of its boiling characteristics were 270.1 °C for peak temperature and 244.1 J g⁻¹ for the enthalpy variation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

SBR composites reinforced with <Emphasis Type="Italic">N</Emphasis>-isopropyl-<Emphasis Type="Italic">N</Emphasis>′-phenyl-<Emphasis Type="Italic">P</Emphasis>-phenylenediamine-modified clay

SBR compounds including the N-isopropyl-N’-phenyl-p-phenylenediamine-modified clay(organoclay) were prepared.Effects of modified clay and antioxidant(IPPD) contents on mechanical and rheological properties of SBR composites were studied.FTIR results confirmed that the clay was chemically modified by IPPD and changed into an organoclay.X-ray diffraction(XRD) results confirmed the increase in interlayer distance of the clay due to the insertion of IPPD.Rheological and cure characteristics of SBR compounds were determined using RPA(Rubber Process Analyzer) and rheometer.Scorch time and cure time of SBR compounds decreased with introduction of the organoclay.Mechanical properties and heat aging resistance of the SBR composites were improved significantly by incorporation of the organoclay.     

Theoretical and experimental NMR studies of the Swern oxidation of methyl 6<Emphasis Type="Italic">α</Emphasis>,7<Emphasis Type="Italic">β</Emphasis>-dihydroxyvouacapan-17<Emphasis Type="Italic">β</Emphasis>-oate

This work describes the synthesis of new derivatives of 6α,7β-dihydroxyvouacapan-17β-oic acid (1) employing the Swern method for the oxidation of C-6 and C-7 of methyl 6α,7β-di-hydroxyvouacapan-17β-oate (2) and the formation of methyl 6,7-dioxovouacapan-17β-oate (3). NMR structural studies associated with theoretical calculations of reaction intermediates and products are also reported. The mixture of methyl 7β-hydroxy-6-oxovouacapan-17β-oate (4; 21%) and methyl 6α-hydroxy-7-oxovouacapan-17β-oate (5; 79%) was the product from the first step of the oxidation of 2. The lower energy of 5, calculated by HF/6-31G* and DFT/BLYP/6-31G* methods, reinforces the thermodynamic control proposed for the reaction. After further Swern oxidation of the mixture of 4 and 5, the isomeric form methyl 6-hydroxy-7-oxovouacap-5-en-17β-oate (6) was obtained. Theoretical calculations indicate a lower energy for the mono-enol 6 than the 1,2-diketo 3 and the other mono-enol methyl 7-hydroxy-6-oxovouacap-7-en-17β-oate (7).     

Oxidation of reaction products of <Emphasis Type="Italic">p</Emphasis>-aryl-<Emphasis Type="Italic">С</Emphasis>,<Emphasis Type="Italic">С</Emphasis>-disubstituted nitrones and dimethyl 3-methylenecyclopropane-1,2-dicarboxylate

Oxidation with 2,3-dichloro-4,5-dicyanobenzoquinone of 2,4-dihydro-1Н-azeto[1,2-a]quinoline-3,4 -dicarboxylates obtained in the reaction of N-aryl-С,С-disubstituted nitrones with Feist’s acid ester resulted in the formation of 2-vinylquinoline-3,4-dicarboxylates in good yields.