New chiral polyfunctional cyclobutane derivatives from (−)-verbenone: possible surfactant behaviour

New enantiopure cyclobutane derivatives have been synthesized from a chiral precursor derived from (?)-verbenone. The cyclobutane moiety acts as a chiral platform to afford a γ-amino acid function in a branched side-chain containing an additional stereogenic centre as well as additional C₆ or C₁₆-alkyl chains linked to the ring by means of an amine or an amide function. One of these compounds, obtained as a 1:2 mixture with its TFA salt has been investigated, suggesting behaviour as a good surfactant and its critical micellar concentration has been determined.     

New derivatives of poly-hexafluoropropylene oxide from the corresponding alcohol

Poly-hexafluoropropylene oxide (poly-HFPO) alcohol was prepared by the reduction of the corresponding methyl ester using NaBH_4, NaBD₄, or LiAlH₄ (LAH). This alcohol is a versatile starting material for the preparation of additional interesting compounds. Because of its expected poor nucleophilicity, before attempting additional reactions, we have found it advantageous to prepare a corresponding salt. We have found that the resulting salt behaved like a normal hydrocarbon alkoxide. The reaction of this salt with either acetyl chloride or allyl chloride (or bromide) gave the expected products which proved to be normal nucleophilic substitutions. In addition, the bromination of the allyl ether was studied using NMR and GC/MS techniques.     

Effect of Mechanical Activation on the Reaction of Magnesium Hydride with Water

The effect of the parameters of mechanochemical activation of magnesium hydride and MgH₂-graphite binary compositions on the parameters of materials and their hydrolytic activity has been studied. It is concluded that mechanochemical treatment increases the reactivity of magnesium hydride in its reaction with water. Graphite provides an additional activating effect during the mechanochemical treatment of MgH₂. A deformation dose of 20 kJ/g was determined to be the optimum one for achieving the highest reactivity in the hydrolysis reaction with the formation of MgH₂-graphite composites. As a result of the hydrolysis of such materials, up to 970–1280 mL hydrogen per composite gram is evolved in 40 min of the reaction with water without an additional change in the solution acidity.     

Palladium-catalyzed hydroarylation of alkynes with arylboronic acids

Reaction of symmetrical and unsymmetrical alkynes with arylboronic acids, using PdCl₂ as catalyst source and i-Pr₂NPPh₂ as ligand, afforded trisubstituted alkenes with regioselectivity in good to excellent yields without a common additional acetic acid. Its efficiency has been demonstrated by its good functional groups, high yield and crowded substrates.     

Efficient fixation of CO2 at mild conditions by a Cr-conjugated microporous polymer

We reported a bifunctional material, Cr-salen implanted conjugated microporous polymer (Cr-CMP), which is able to capture excellent CO₂ amounts and has a remarkable catalytic activity towards the cycloaddition reaction of CO₂ to epoxides forming cyclic carbonates at mild conditions without additional solvents. This heterogeneous Cr-CMP catalyst has a superior catalytic activity to its related homogeneous catalyst and can be reused more than ten times without a significant decrease in catalytic activity.     

Horizontal and vertical configurations of molecular N2O on W(110) and Ru(001)

The adsorption of N₂O on W(110) and Ru(001) has been investigated by means of XPS and UPS including some angle-dependent measurements. Besides dissociation, molecular N₂O states were observed, which could be identified to be physisorbed horizontally. On Ru(001), an additional weakly chemisorbed state can coexist which is vertically adsorbed via its terminal N atom.     

Thermochemical Study of Mixed-Ligand Manganese(II) Ethylenediaminetetraacetate Complex with Ammonia in Aqueous Solution

Formation of the mixed-ligand complex [MnEdtaNH₃]^2– and of the Mn(II) ammine complex is studied by calorimetry at 298.15 K and ionic strength I = 0.5 (NH₄NO₃). Thermodynamic parameters of the reaction of attachment of the additional ligand to the manganese(II) chelate are determined; its probable mechanism is discussed.     

Development of a novel RP‐HPLC method for the efficient separation of aripiprazole and its nine impurities

The development of an RP‐HPLC method for the separation of aripiprazole and its nine impurities was performed with the use of partial least squares regression, response surface plot methodology, and chromatographic response function. The HPLC retention times and computed molecular parameters of the aripiprazole and its nine impurities were further used for the quantitative structure–retention relationship (QSRR) study. The QSRR model, R²: 0.899, Q²: 0.832, root mean square error of estimation: 4.761, root mean square error of prediction: 6.614, was developed. Very good agreement between the predicted and observed retention times (t_R) for three additional aripiprazole impurities (TC1–TC3) indicated the high prediction potential of the QSRR model for t_R evaluation of other aripiprazole impurities and metabolites. The developed HPLC method is the first reported method for the efficient separation of aripiprazole and its nine impurities, which could be used for the analysis of an additional three aripiprazole impurities (TC1–TC3).     

Transitions de phases multiples et propriétés ferroïques de Pb5Al3F19

Pb₅Al₃F₁₉, a member of the isostructural Pb₅M₃F₁₉, family with M = Al, Ti, V, Cr, Fe and Ga, differs from the remaining members in having three additional phases between its ferroelectric phase V and its paraelectric phase I. Phase IV is shown to be antiferroelectric, phase III ferroelastic and phase II paraelastic. Each phase has been fully characterized. Formation of the three extra phases is attributed to interactions between the 6(sp)² lone electron pair of the Pb² ion and volume effects related to the small Al³⁺ ion.     

Low-Temperature Triclinic Distortion in NASICON-Type LiSn2(PO4)3

The triclinic nature of the low-temperature modification of LiSn₂(PO₄)₃, heretofore considered as monoclinic, has been proved by detailed indexing of its X-ray diffraction powder pattern. The triclinic character of most low-temperature polymorphs of NASICON-type LiMe^IV₂(PO₄)₃is tentatively hypothesized, from this evidence and additional indications.     

Synthesis of ultra-high-silica ZSM-5 zeolites with tunable crystal sizes

Using silicalite-1 suspension as seed crystals and a small amount of tetraallkylammonium bromide as additional structure-directing agent, highly crystallized ZSM-5 with SiO₂/Al₂O₃ ratios higher than 100 was obtained. The crystal sizes could be easily tuned from tens of nanometers to about several micronmeters by merely adjusting the amount of the seeding suspension. Seeding suspension synthesized from different silica sources and the additional structure-directing agent may also affect the crystal sizes. The synthesized samples were characterized by powder X-ray diffraction, scanning electron microscopy, N₂ adsorption–desorption and inductively coupled plasma. When tetraethylammonuim bromide was used as additional structure-directing agent, crystals with silica-rich cores were observed, while additional nucleation could be found when tetrapropylammonium bromide was used as auxiliary template.     

The Choice of Polar Stationary Phases for Gas–Liquid Chromatography by Statistical Analysis of Retention Data

We have studied the retention indices of 127 volatile substances on a C₇₈-paraffin and on its seven nearly isochor and isomorphous polar derivatives over a temperature range of 90–210 °C. The retention index of a substance on the C₇₈ paraffin has been considered as the standard. The additional retention on the polar derivative was given by the difference of its retention index on the polar solvent and on the C₇₈-paraffin. Statistical analyses of the additional retention have shown that with respect to retention, the seven polar solvents can be classified into three groups: Type I: TTF (tetrakistrifluoromethyl), MTF (monotrifluoromethyl), Type II: PCN (primary cyano), PSH (primary thiol) and Type III: TMO (tetramethoxy), SOH (secondary alcohol) and POH (primary alcohol). It is shown that these three types are best represented by the solvents TTF, PCN and TMO. PSH (primary thiol) is aligned with PCN at temperatures up to about 150 °C, but is similar to TMO at 210 °C.     

Thermal and plasmochemical activation of the zirconia-supported copper catalyst for ethanol dehydrogenation

It was shown that copper-containing nanocomposites based on t-zirconium dioxide 5% Cu/t-ZrO₂ can be activated using preliminary treatments in high-frequency (HF) hydrogen plasma and critical low-temperature treatments. The increased activity was explained by the formation of many active centers due to the creation of additional t-zirconia defects as a result of the redistribution of copper ions on its surface before the reductive treatment.     

Fullerene C70 as a Nanoflask that Reveals the Chemical Reactivity of Atomic Nitrogen

To investigate the intrinsic reactivity of atomic nitrogen, which had previously been accomplished only by examining its decay in the gas phase using special equipment, a nitrogen atom was inserted into a series of molecule-encapsulating C₆₀ and C₇₀ fullerenes. Among the studied endofullerenes, H₂@C₇₀ was able to encapsulate an additional nitrogen atom within the fullerene cage under radiofrequency plasma conditions. The product was analyzed by ESR spectroscopy and mass spectrometry in solution, which revealed that the nitrogen atom with a quartet ground state does not react but weakly interact with the H₂ molecule, thus demonstrating the utility of such fullerenes as “nanoflasks”.     

Chemical fixation of CO2 with highly efficient ZnCl2/[BMIm]Br catalyst system

The chemical fixation of CO₂ with mono-substituted terminal epoxides or cyclohexene oxide to form cyclic carbonates under the ZnCl₂/[BMIm]Br catalyst system without using additional organic solvents was achieved in excellent selectivity (>98%) and TOF (5410 h⁻¹) and the catalyst could be used six times almost without losing its catalytic activity and selectivity. Besides, the pure cis-cyclic carbonate of cyclohexene oxide was obtained in this catalyst system.     

Symmetry properties of chemical graphs. IX. The valence tautomerism in the P73− skeleton

We investigate the intramolecular rearrangement of the P₇^3? ion in which P? P bonds are continuously broken and reestablished resulting in a dynamic structure with all seven phosphorus atoms being chemically equivalent. This leads to 7/3 = 1680 valence tautomers. The P₇^3? ion is a typical fluctuating molecule, distantly related to C₁₀H₁₀ bullvalene. In order to determine the symmetry of the process we first consider the problem of the construction of the rearrangement graph. Initial steps toward this goal are illustrated, and additional characterizations of the graph are derived after its construction by computer. A number of properties of this rather complicated graph having 1680 vertices and 2520 edges are discussed: in particular the occurrence of various cycles, the maximal distance between vertices, the count of neighbors at different distance, and finally its symmetry.     

4‐Oxo­cyclo­hexane­carboxyl­ic acid: hydrogen bonding in the monohydrate of a δ‐keto acid

The title monohydrate, C₇H₁₀O₃·H₂O, aggregates as a complex hydrogen‐bonding network, in which the water mol­ecule accepts a hydrogen bond from the carboxyl group of one mol­ecule and donates hydrogen bonds to ketone and carboxyl Czdbnd;O functions in two additional mol­ecules, yielding a sheet‐like structure of parallel ribbons. The keto acid adopts a chiral conformation through rotation of the carboxyl group by 62.50 (15)° relative to the plane defined by its point of attachment and the ketone C and O atoms. Two C—H⋯O close contacts exist in the structure.     

Thermal decomposition of ammonium dinitramide and mechanism of anomalous decay of dinitramide salts

Thermal decomposition of ammonium dinitramide proceedsvia homolytic rupture of the N−NO₂ bond and partially by the proton transfer reaction. The monomolecular decay of the anion to N₂O and NO₃ ⁻ in the solid state at 60 °C occurs with higher rates than those in the melt. This is related to a change in the reactivity of the anion due to the violation of its symmetry on going to the solid state. The absence of hydrogen bonds between the anion and cations or water molecules is an additional condition for the fast decay. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 50–54, January, 1999.     

Di(phenylpropylamino)gossypol: a derivative of the dimeric natural product gossypol

Di(phenylpropylamino)gossypol [systematic name: 2,2′‐bis{1,6‐dihydroxy‐5‐isopropyl‐8‐[(3‐phenylpropylamino)methylidene]naphthalen‐7‐one}, C₄₈H₅₂N₂O₆, was formed by reaction of the dimeric natural product gossypol with 3‐phenylpropylamine. The structure of this compound has its two naphthalene ring systems oriented approximately perpendicular to each other, and the two pendant phenylpropyl groups have different conformations. One of these side groups is considerably disordered at room temperature but less so at 120 K. The enantiomeric molecules form centrosymmetric dimers that are supported by intermolecular hydrogen bonds and by hydrophobic interactions between a pair of naphthalene rings. Two additional hydrogen bonds tie the dimer pairs into layers. Unlike gossypol and many gossypol Schiff base derivatives, the title compound crystallizes without the inclusion of solvent, which appears to occur because of the size and flexibility of its phenylpropyl pendent groups.     

Development and evaluation of a detailed mechanism for the atmospheric reactions of isoprene and NOx

A detailed photochemical mechanism for the atmospheric reactions of isoprene and its major oxidation products in the presence of NO_x, which incorporates the most recent laboratory results and our current understanding of the system, is described. It is evaluated by comparing its predictions against results of NO_x-air irradiations of isoprene and its two major products, methacrolein, and methyl vinyl ketone (MVK), in five different types of environmental chambers at two different laboratories. In most cases it simulated experimental results within the uncertainty of the data and the chamber and run characterization model. However, the photodecomposition quantum yields of methacrolein and MVK and the organic nitrate yield from the OH + isoprene reaction had to be adjusted to obtain satisfactory simulations of the data. The major discrepancy observed was that the model tended to underpredict PAN by ca. 40% in the isoprene experiments, despite the fact that the model predicted PAN from methacrolein and MVK reasonably well. The uncertainties and additional data needed to completely characterize the isoprene atmospheric photooxidation system are discussed. © 1996 John Wiley & Sons, Inc.