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In this work, we report a more simple and efficient way to synthesize a composite ionic liquid (IL) ([BMIM][[Zn.sub.2][Br.sub.5]]) by directly coupling the IL with molecular sieves. Two kinds of immobilized catalysts were successfully synthesized: SBA-15-[BMIM] [[Zn.sub.2][Br.sub.5]] and SBA-15-CPTES-[BMIM][[Zn.sub.2][Br.sub.5]]. The catalysts were used to catalyze the cycloaddition reaction of continuous transformation of C[O.sub.2] and propylene oxide, and the catalytic performance of catalysts was further studied. Compared with the traditional IL catalysts, the catalysts not only have excellent catalytic performance, but also have a significantly longer service life. This is because the catalysts are formed by a high energy chemical bond of silane between IL catalysts and molecular sieves, which can effectively solve the problem of the loss of IL active components in the catalytic process. Key words: composite ionic liquid, SBA-15, silane coupling agent, immobilized catalyst, C[O.sub.2]. Dans le cadre des presents travaux, nous decrivons une facon plus simple et efficace de synthetiser le liquide ionique (LI) composite ([BMIM][[Zn.sub.2][Br.sub.5]]) par couplage direct du LI avec des tamis moleculaires. Nous sommes parvenus a synthetiser deux types de catalyseurs immobilises, soit le SBA15[BMIM][[Zn.sub.2][Br.sub.5]] et le SBA15CPTES-[BMIM][[Zn.sub.2][Br.sub.5]]. Nous avons utilise ces catalyseurs pour catalyser la reaction de cycloaddition dans la transformation continue du C[O.sub.2] et de l'oxyde de propylene, et nous avons etudie plus en detail leur performance catalytique. Ces catalyseurs offrent non seulement une excellente performance catalytique, mais celle-ci surpasse celle des catalyseurs traditionnels a base de LI, et leur duree de vie utile est considerablement plus longue. Ces caracteristiques s'expliquent par le fait que ces catalyseurs sont formes de liaisons silane hautement energetiques entre le catalyseur a base de LI et le tamis moleculaire, ce qui permet de resoudre efficacement le probleme de la perte de composants actifs du LI au cours du processus catalytique. [Traduit par la Redaction] Mots-cles : liquide ionique composite, SBA-15, agent de couplage a base de silane, catalyseur immobilise, C[O.sub.2]., 1. Introduction The rapid development of the modern industry has resulted in a sharp rise in C[O.sub.2] emission, which causes worldwide problems such as global warming and the El Nino [...]

In this work, activated carbon supported Cu-MOF was used as an acetylene hydrochlorination catalyst to manufacture vinyl chloride. Cu-MOF/AC with 15 wt. % Cu-MOF content has the initial acetylene conversion of 99.2% and vinyl chloride selectivity of 98.5% at 200 [degrees]C. By combining steady-state experiments and physical--chemical characterization results (XPS, BET, [H.sub.2]-TPR, [C.sub.2][H.sub.2]-TPD, XRD, and HCl adsorption experiments), Cu--O--C is shown to slow the reduction of [Cu.sup.2+], improve the reactants adsorption, and strengthen the anti-coking ability of Cu-based catalysts. According to the previous studies and the Eley--Rideal mechanism, it is proposed that [Cu.sup.2+] first adsorbed [C.sub.2][H.sub.2] to generate transition states in acetylene hydrochlorination catalysis. Key words: Cu-MOFs, acetylene hydrochlorination, vinyl chloride. Dans le cadre de ces travaux, nous avons utilise le charbon active (AC) comme support a un reseau metallo-organique a base de cuivre (CuMOF) que nous avons employe comme catalyseur d'hydrochloration de l'acetylene pour la fabrication du chlorure de vinyle. Le CuMOF/AC contenant 15 % p/p de CuMOF convertit 99,2 % de l'acetylene initial pour produire le chlorure de vinyle avec une selectivite de 98,5 % a 200 [degrees]C. En combinant les resultats d'experiences a l'etat d'equilibre et de caracterisation physicochimique (spectroscopie de photoelectrons X [XPS], analyse par la methode Brunauer--Emmet--Teller [BET], reduction thermoprogrammee sous hydrogene [[H.sub.2]RTP], desorption thermoprogrammee d'hydrogene [[H.sub.2]DTP] et experiences d'adsorption de HCl), nous avons montre que la liaison Cu--O--C retarde la reduction du [Cu.sup.2+], ameliore l'adsorption des reactifs et renforce la capacite anti-cokefaction des catalyseurs a base de cuivre. D'apres les etudes precedentes et le mecanisme de Eley--Rideal, nous posons l'hypothese selon laquelle le [Cu.sup.2+] s'adsorberait d'abord sur le [C.sub.2][H.sub.2] pour generer les etats de transition correspondant a la catalyse de l'hydrochloration de l'acetylene. Mots-cles : CuMOF, hydrochloration de l'acetylene, chlorure de vinyle., 1. Introduction Metal--organic frameworks (MOF), as a new class of porous coordination polymer constituted by inorganic building units and an organic linker, have been rapidly developed in many applications, such [...]

Boron functional groups are often introduced in place of aromatic carbon-hydrogen bonds to expedite small-molecule diversification through coupling of molecular fragments.sup.1-3. Current approaches based on transition-metal-catalysed activation of carbon-hydrogen bonds are effective for the borylation of many (hetero)aromatic derivatives.sup.4,5 but show narrow applicability to azines (nitrogen-containing aromatic heterocycles), which are key components of many pharmaceutical and agrochemical products.sup.6. Here we report an azine borylation strategy using stable and inexpensive amine-borane.sup.7 reagents. Photocatalysis converts these low-molecular-weight materials into highly reactive boryl radicals.sup.8 that undergo efficient addition to azine building blocks. This reactivity provides a mechanistically alternative tactic for sp.sup.2 carbon-boron bond assembly, where the elementary steps of transition-metal-mediated carbon-hydrogen bond activation and reductive elimination from azine-organometallic intermediates are replaced by a direct, Minisci.sup.9-style, radical addition. The strongly nucleophilic character of the amine-boryl radicals enables predictable and site-selective carbon-boron bond formation by targeting the azine's most activated position, including the challenging sites adjacent to the basic nitrogen atom. This approach enables access to aromatic sites that elude current strategies based on carbon-hydrogen bond activation, and has led to borylated materials that would otherwise be difficult to prepare. We have applied this process to the introduction of amine-borane functionalities to complex and industrially relevant products. The diversification of the borylated azine products by mainstream cross-coupling technologies establishes aromatic amino-boranes as a powerful class of building blocks for chemical synthesis. Selective borylation of azines--nitrogen-containing aromatic heterocycles used in the synthesis of many pharmaceuticals--is made possible by forming a radical from an aminoborane using a photocatalyst., Author(s): Ji Hye Kim [sup.1] , Timothée Constantin [sup.1] , Marco Simonetti [sup.1] , Josep Llaveria [sup.2] , Nadeem S. Sheikh [sup.3] , Daniele Leonori [sup.1] Author Affiliations: (1) Department [...]

Reactions of Cp*OsCl[([PPh.sub.3]).sub.2] (Cp* = pentamethylcyclopentadienyl) with alkynes and alkynols are described. Treatment of Cp*OsCl[([PPh.sub.3]).sub.2] with phenylacetylene and trimethylsilylacetylene gave the vinylidene complexes Cp*OsCl [(=C=CHPh)([PPh.sub.3]) and Cp*OsCl(=C=[CH.sub.2])([PPh.sub.3]), respectively. Treatment of Cp*OsCl([PPh.sub.3]).sub.2] with the internal alkyne dimethyl acetylenedicarboxylate produced the [[eta].sup.2]-alkyne complex Cp*OsCl[([[eta].sup.2]-[MeO.sub.2]C:[CCO.sub.2]Me)([PPh.sub.3]). Treatment of Cp*OsCl([PPh.sub.3]).sub.2] with the propargylic alcohol HC:CC(OH)[Ph.sub.2] gave the osmium allenylidene complex Cp*OsCl(=C = C=[CPh.sub.2])([PPh.sub.3]). The outcomes of the reactions of Cp*OsCl[([PPh.sub.3]).sub.2] with [omega]-alkynols HC:C[([CH.sub.2]).sub.n]OH are dependent on the length of the -[([CH.sub.2]).sub.n]- linker. The reaction with 3-butyn-1-ol produced the cyclic oxycarbene complex Cp*OsCl{=C[([CH.sub.2]).sub.3]O}([PPh.sub.3]) exclusively. The reactions with 4-pentyn-1-ol produced a mixture of the hydroxyalkyl vinylidene complex Cp*OsCl{=C=CH[([CH.sub.2]).sub.3]OH}([PPh.sub.3]) and the cyclic oxycarbene complex Cp*OsCl{=C[([CH.sub.2]).sub.4]O}([PPh.sub.3]) in about 10:1 molar ratio. The reaction with 5-hexyn-1-ol gave exclusively the hydroxyalkyl vinylidene complex Cp*OsCl{=C=CH[([CH.sub.2]).sub.4]OH}([PPh.sub.3]). Key words: osmium, vinylidene, allenylidene, alkyne, alkynol. Nous decrivons les reactions du complexe Cp*OsCl[([PPh.sub.3]).sub.2] (Cp* = pentamethylcyclopentadienyl) avec des alcynes et des alcynols. Le traitement du complexe Cp*OsCl[([PPh.sub.3]).sub.2] avec le phenylacetylene et le trimethylsilylacetylene a produit les complexes de vinylidene Cp*OsCl(=C=CHPh)([PPh.sub.3]) et Cp*OsCl(=C=[CH.sub.2])([PPh.sub.3]), respectivement. Le traitement du complexe Cp*OsCl[([PPh.sub.3]).sub.2] avec un alcyne interne, l'acetylenedicarboxylate de dimethyle, a donne lieu a la formation du complexe de [[eta].sup.2]alcyne Cp*OsCl[([[eta].sup.2][MeO.sub.2]C:[CCO.sub.2]Me)([PPh.sub.3]). En traitant le complexe Cp*OsCl([PPh.sub.3]).sub.2] avec l'alcool propargylique HC:CC(OH)[Ph.sub.2], nous avons obtenu le complexe d'allenylideneosmium Cp*OsCl(=C=C=[CPh.sub.2])([PPh.sub.3]). Les produits des reactions du complexe Cp*OsCl[([PPh.sub.3]).sub.2] avec les [omega] alcynols HC:C[([CH.sub.2]).sub.n]OH dependent de la longueur de l'espaceur [([CH.sub.2]).sub.n]. La reaction avec le 3butyn-1ol a produit exclusivement le complexe oxycarbene cyclique Cp*OsCl{=C[([CH.sub.2]).sub.3]O}([PPh.sub.3]). La reaction avec le 4pentyn-1ol a produit un melange du complexe hydroxyalkylvinylidene Cp*OsCl{=C=CH[([CH.sub.2]).sub.3]OH}([PPh.sub.3]) et du complexe cyclique oxycarbene Cp*OsCl{=C[([CH.sub.2]).sub.4]O}([PPh.sub.3]) dans un rapport molaire de 10:1. La reaction avec le 5hexyn-1ol a donne lieu a la formation exclusive du complexe hydroxyalkylvinylidene Cp*OsCl{=C=CH[([CH.sub.2]).sub.4]OH}([PPh.sub.3]). [Traduit par la Redaction] Mots-cles : osmium, vinylidene, allenylidene, alcyne, alkynol., Introduction Metal vinylidenes and allenylidenes are important species in both stoichiometric and catalytic reactions. (1) Ruthenium (2,3) and osmium (4,5) are among the most popular transition metals for the development [...]

The silatrane hydride compound, [N[([CH.sub.2][CH.sub.2]O).sub.3]]SiH, reacts with [CO.sub.2] in the presence of the [tris(2-pyridylthio)-methyl]zinc hydride complex, [Tptm]ZnH, to afford the silyl formate and methoxide derivatives, [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiO.sub.2]CH and [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiOCH.sub.3]. The molecular structure of [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiO.sub.2]CH has been determined by X-ray diffraction, thereby demonstrating that the formate ligand adopts a distal conformation in which the uncoordinated oxygen atom resides with a trans-like disposition relative to silicon. Density functional theory calculations indicate that the atrane motif of [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiO.sub.2]CH is flexible, such that the energy of the molecule changes relatively little as the Si***N distance varies over the range 2.0-3.0 A. Key words: hydrosilane, [CO.sub.2], silyl formate, atrane, zinc. Le compose d'hydrure de silatrane [N[([CH.sub.2][CH.sub.2]O).sub.3]]SiH reagit avec le [CO.sub.2] en presence du complexe d'hydrure de [tris[(2pyridylthio)methyl]zinc, [Tptm]ZnH, pour former les derives silyles formate et methoxy N([CH.sub.2][CH.sub.2]O).sub.3]][SiO.sub.2]CH et [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiOCH.sub.3]. Nous avons determine la structure moleculaire du compose [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiO.sub.2]CH par diffraction des rayons X, et avons montre ainsi que le ligand formate adopte une conformation distale dans laquelle l'atome d'oxygene non coordonne se trouve dans une configuration pseudo-trans par rapport a l'atome de silicium. Les calculs de theorie de la fonctionnelle de la densite indiquent que le motif atrane du compose [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiO.sub.2]CH est flexible, de sorte que l'energie de la molecule change relativement peu lorsque la distance Si***N varie dans l'intervalle de 2,0 a 3,0 A. [Traduit par la Redaction] Mots-cles : hydrosilane, [CO.sub.2], formate de silyle, atrane, zinc., Introduction There is currently much interest in developing the use of [CO.sub.2] as a renewable [C.sub.1] source for the synthesis of organic chemicals, which also pertains to efforts in countering [...]

A nanocomposite, reduced graphene oxide (RGO) modified Zn[Co.sub.2][O.sub.4] (Zn[Co.sub.2][O.sub.4]-RGO) was synthesized via one-step solvothermal method for activating persulfate (PS) to degrade bisphenol A (BPA). The morphology and structure of the nanocomposite were identified by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. RGO provides nucleation sites for Zn[Co.sub.2][O.sub.4] to grow and inhibits the agglomeration of the nanoparticles. The influence of different reaction conditions on the oxidation of BPA catalyzed by Zn[Co.sub.2][O.sub.4]-RGO was investigated, including the content of RGO, the dosage of catalyst, the concentration of humic acid (HA), anions in the environment, the reaction temperature, and pH. BPA can be totally degraded within 20 min under optimized reaction conditions. The presence of HA, [Cl.sup.-], and N[O.sub.3.sup.-] only has a slight effect on the oxidation of BPA, whereas the presence of either [H.sub.2]P[O.sub.4.sup.-] or HC[O.sub.3.sup.-] can greatly inhibit the reaction. Zn[Co.sub.2][O.sub.4]-RGO shows good cycling stability and practical application potential. A reaction mechanism of the degradation of BPA was also explored. Key words: graphene based nanocomposite, heterogeneous activation, persulfate, advanced oxidation processes, bisphenol A. Nous avons synthetise un nanocomposite de Zn[Co.sub.2][O.sub.4] modifie par l'oxyde de graphene reduit (rGO), le Zn[Co.sub.2][O.sub.4]-rGO, par une methode sovothermale en une etape permettant d'activer le persulfate afin de degrader le bisphenol A (BPA). Nous avons caracterise la morphologie et la structure du nanocomposite par diffraction des rayons X, spectroscopie infrarouge a transformee de Fourier, spectroscopie de photoelectrons X, microscopie electronique a balayage et microscopie electronique en transmission. Le rGO offre des sites de nucleation permettant la croissance des cristaux de Zn[Co.sub.2][O.sub.4] et inhibe l'agglomeration des nanoparticules. Nous avons etudie l'influence de differentes conditions de reaction sur l'oxydation du BPA catalysee par le Zn[Co.sub.2][O.sub.4]-rGO, a savoir la teneur en rGO, la quantite de catalyseur, la concentration d'acide humique (AH), la presence d'anions dans le milieu, la temperature de reaction et le pH. En conditions de reaction optimisees, le BPA peut etre totalement degrade en moins de 20 minutes. La presence d'AH et d'ions [Cl.sup.-] et N[O.sub.3.sup.-] n'ont qu'un leger effet sur l'oxydation du BPA, tandis que la presence d'ions [H.sub.2]P[O.sub.4.sup.-] ou d'ions HC[O.sub.3.sup.-] peut inhiber grandement la reaction. Le Zn[Co.sub.2][O.sub.4]-rGO presente une bonne stabilite au cours des cycles successifs et offre des possibilites d'applications pratiques. Nous avons egalement explore un mecanisme de reaction de la degradation du BPA. [Traduit par la Redaction] Mots-cles : nanocomposite a base de graphene, activation heterogene, persulfate, procedes d'oxydation avances, bisphenol A., Introduction Bisphenol A (BPA) is commonly used for producing polycarbonate plastics and epikotes (1) and can also be utilized as an additive in flame retardants, brake fluid, and thermal papers. [...]

Barium-lanthanum britholite solid solutions, [Ba.sub.10-x][La.sub.x][(P[O.sub.4]).sub.6-x][(Si[O.sub.4]).sub.x][F.sub.2], with 0 [less than or equal to] x [less than or equal to] 6 were prepared by solid state reaction in the temperature range of 1200-1400 [degrees]C. The powders were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES), F-selective electrode, X-ray diffraction (XRD), and Fourier transform infrared (FTIR). In addition, the present study used thermal analysis to follow the apatite formation reaction during the heat treatment. For x [less than or equal to] 3, there is formationof asingle apatite phase, whereas above this value, the [La.sub.2]Si[O.sub.5], [La.sub.2][Si.sub.2][O.sub.7], Ba[Si.sub.2][O.sub.5], and [Ba.sub.2][La.sub.2][O.sub.5] secondary phases were observed. The variation of the lattice parameters of the apatite phase as a function of x confirmed that the solid solution is discontinuous to either side of x = 3. Key words: apatite, lanthanum, barium, DRX. Resume : Nous avons prepare des solutions solides de britholite au baryum et lanthane de formule [Ba.sub.10-x][La.sub.x][(P[O.sub.4]).sub.6-x][(Si[O.sub.4]).sub.x][F.sub.2], ou 0 [less than or equal to] x [less than or equal to] 6, par reaction a l'etat solide dans l'intervalle de temperatures de 1 200 a 1 400 [degrees]C. Nous avons analyse les poudres par spectrometrie d'emission atomique a plasma a couplage inductif (ICP-AES), electrode a fluorure, diffraction des rayons X (DRX) et spectroscopie infrarouge a transformee de Fourier (FTIR). Dans le cadre de la presente etude, nous avons en outre employe l'analyse thermique pour suivre la reaction de formation de l'apatite pendant le traitement thermique. Dans les cas ou x [less than or equal to] 3, on a observe la formation d'une seule phase d'apatite, tandis qu'au-dela de cette valeur, les phases secondaires de [La.sub.2]Si[O.sub.5], [La.sub.2][Si.sub.2][O.sub.7], Ba[Si.sub.2][O.sub.5] et [Ba.sub.2][La.sub.2][O.sub.5] ont ete observees. La variation des parametres de reseau de la phase d'apatite en fonction de x a permis de demontrer que la solution solide est discontinue de part et d'autre de x = 3. [Traduit par la Redaction] Mots-cles : apatite, lanthane, baryum, DRX., Introduction The hydroxyapatite ([Ca.sub.10][(P[O.sub.4]).sub.6][(OH).sub.2], HAp), the main representative of the apatite's family, has been extensively investigated for various medical applications mainly in orthopedics and dentistry. (1-3) Also, the apatites have [...]

Molybdenum trioxide (Mo[O.sub.3]) microplates are synthesized via the hydrothermal method and a simple heat treatment process without adding surfactant. Different hydrothermal reaction times and acidities are employed to explore the influence of preparation condition on the electrochemical performance for Mo[O.sub.3] microplates. These studies reveal that the hydrothermal time and acidity have a great impact on the morphology of Mo[O.sub.3] microplates. As anode materials for lithium-ion batteries (LIBs), the sheets-assembled Mo[O.sub.3] microplates with longer hydrothermal reaction time and proper acidity possess a superior morphology, which show better cycling performance and rate capability stability. The prepared Mo[O.sub.3] microplates display that the coulombic efficiency is around 100% during 50 cycles, demonstrating much better lithium storage properties. Considering the excellent electrochemical performance, the Mo[O.sub.3] microplates are considered to be a potential candidate in high-performance LIBs. Key words: molybdenum trioxide, hydrothermal method, lithium-ion battery, energy conversion. Resume : Nous avons synthetise des microplaques de trioxyde de molybdene (Mo[O.sub.3]) par une methode hydrothermale et un procede simple de traitement thermique sans ajout de surfactant. La reaction hydrothermale a ete realisee a differents temps de reaction et degres d'acidite en vue d'explorer l'influence des conditions de reaction sur la performance electrochimique des microplaques de Mo[O.sub.3]. Ces etudes revelent que le temps de reaction et l'acidite de la reaction hydrothermale ont un effet important sur la morphologie des microplaques de Mo[O.sub.3]. Comme materiau d'anode dans des batteries au lithium-ion (BLI), les microplaques de Mo[O.sub.3] assemblees en feuillets qui ont beneficie d'un temps de reaction hydrothermale plus long et d'une acidite du milieu reactionnel adequate possedent des proprietes morphologiques superieures qui leur conferent une meilleure performance au fil des cycles de charge et une plus grande stabilite de la capacite de debit. Les microplaques de Mo[O.sub.3] que nous avons preparees presentent un rendement coulombien d'environ 100 % durant 50 cycles, ce qui temoigne de proprietes de stockage considerablement superieures au lithium. Compte tenu de leur excellente performance electrochimique, les microplaques de Mo[O.sub.3] pourraient etre appliquees a des BLI a haut rendement. [Traduit par la Redaction] Mots-cles : trioxyde de molybdene, methode hydrothermale, batterie au lithium-ion, transformation d'energie., Introduction Lithium-ion batteries (LIBs), as electrical energy storage devices, have attracted tremendous attention because of their substantial advantages such as light weight, high energy density, enhanced safety, and long cycle [...]

Syntheses are reported for: nine 2-nitroimidazoles, the abbreviated names all beginning with E, based on derivation from Etanidazole); five 2-methyl-5-nitroimidazoles (Mcompounds, derived from Metronidazole); and five 2-methyl-4-nitroimidazoles (labelled 2M4N compounds). The nitroimidazoles all have an amide side-chain at the N1 atom of the imidazole, with 17 of them containing one to five halogen atoms. The aim is to study compounds for comparison with EF5 (the number showing the presence of five F-atoms), a previously reported, pentafluoropropylacetamide derivative of 2-nitroimidazole that is currently used as a hypoxia marker drug to detect cancerous tumours. The new compounds are characterized by standard methods, including X-ray structural data for the fluorinated MF5, 2M4NF5, and 2M4NF1(-1) species, with the '-1' indicating two C-atoms in an alkylamide chain rather than the three C-atoms in the propylacetamide of EF5. Intra- and inter-molecular H-bonding is seen in the solid state structures, likely an important property in biological use; another key property of the nitroimidazoles is their reduction potentials, and the measured CV data confirm that 2N[O.sub.2]Im compounds with longer side-chains and more F-atoms (like EF5) are worth investigating for possible activity as hypoxia-selective, bioreductive agents. Key words: 2-nitroimidazole, 4-nitroimidazole, and 5-nitroimidazole, crystal structures, reduction potentials, hypoxic markers. Resume : Nous presentons la synthese de neuf 2-nitroimidazoles, dont les noms abreges commencent tous par la lettre E, en raison de leur derivation a partir de l'etanidazole); de cinq 2-methyl-5-nitroimidazoles (composes M, derives du metronidazole); et de cinq 2-methyl-4-nitroimidazoles (appeles composes 2M4N). Ces nitroimidazoles possedent tous une chaine laterale amide sur l'atome N1 de l'imidazole, 17 d'entre eux contiennent d'un a cinq atomes d'halogene. L'objectif consistait a etudier ces composes afin de les comparer a l'EF5 (le nombre indiquant la presence de cinq atomes de fluor), un derive pentafluoropropylacetamide du 2-nitroimidazole publie precedemment. L'EF5 est un medicament utilise actuellement comme marqueur de l'hypoxie pour la detection de tumeurs cancereuses. Les nouveaux composes ont ete caracterises par les methodes standards, notamment les donnees radiocristallographiques de la structure des especes fluorees MF5, 2M4NF5 et 2M4NF1(-1). A noter que le << -1 >> indique deux atomes de carbone dans une chaine alkylamide au lieu des trois atomes de carbone de la chaine propylacetamide de l'EF5. Nous avons observe des liaisons hydrogene intramoleculaires et intermoleculaires dans les structures a l'etat solide, une propriete probablement importante du point de vue biologique. Une autre propriete importante des nitroimidazoles repose sur leur potentiel de reduction. En effet, les donnees experimentales de voltamperometrie cyclique indiquent que les composes de type 2N[O.sub.2]Im dotes de chaines laterales plus longues et d'un plus grand nombre d'atomes de fluor (comme l'EF5) sont dignes d'interet en ce qui concerne l'etude d'une eventuelle activite comme agents bioreducteurs selectifs de l'hypoxie. [Traduit par la Redaction] Mots-cles : 2-nitroimidazole, 4-nitroimidazole, 5-nitroimidazole, structures cristallines, potentiels de reduction, marqueurs hypoxiques., Introduction Two decades ago, (1) our group in conjunction with others reported on an improved synthesis and an X-ray structure of EF5, a pentafluoropropyl acetamide derivative of 2-nitroimidazole (Chart 1), [...]

Methyl substituted 3-hydroxypyridin-4([.sup.1]H)-ones have been synthesized. The p[K.sub.a] values and [Fe.sup.3+] affinity constants of these ligands were studied. The introduction of an electron-donating methyl group at a different position of pyridinone ring markedly influences the p[K.sub.a] values of 3-hydroxy and 4-oxo groups. The p[Fe.sup.3+] values were also affected and are in the range of 17.6-20.7. The findings can be used to guide a design of 3-hydroxypyridin-4-ones with desirable p[K.sub.a] and p[Fe.sup.3+] values. Key words: iron chelators, 3-hydroxypyridin-4-ones, methyl substituted, p[Fe.sup.3+], electron-donating group, p[K.sub.a]. Resume : Nous avons synthetise des 3-hydroxypyridin-4([.sup.1]H)-ones substituees par un groupe methyle. Nous avons etudie les p[K.sub.a] de ces ligands et leurs constantes d'affinite pour le [Fe.sup.3+]. La position d'un groupe methyle electrodonneur sur le noyau pyridinone influence considerablement les valeurs de p[K.sub.a] des groupes 3-hydroxy et 4-oxo, et modifie egalement les valeurs de p[Fe.sup.3+], qui se situent dans un intervalle de 17,6 a 20,7. Ces resultats peuvent permettre d'orienter la conception de 3-hydroxypyridin-4-ones qui poss-dent des valeurs souhaitables de p[K.sub.a] et de p[Fe.sup.3+]. [Traduit par la Redaction] Mots-cles : chelateurs du fer, 3-hydroxypyridin-4-ones, substitue par un groupe methyle, p[Fe.sup.3+], groupe electrodonneur, p[K.sub.a]., Introduction Deferiprone (6) is an orally active iron-selective chelator that is widely used to treat systemic iron overload associated with regular blood transfusion. (1,2) It is highly effective at removing [...]

The reaction of diorganotin(IV) oxides, [R.sub.2]SnO with R = n-butyl and t-butyl, with nitric acid in different stoichiometric ratios resulted in the formation of different products depending on the organic groups attached to the tin atom: the diorganotin(IV) dinitrate dihydrates, n-[Bu.sub.2]Sn[(N[O.sub.3]).sub.2] x 2[H.sub.2]O (2d) and t-[Bu.sub.2]Sn[(N[O.sub.3]).sub.2] x 2[H.sub.2]O (2e), the mixed diorganotin(IV) nitrate methoxide oxide n-[Bu.sub.2]Sn(N[O.sub.3]) (n-[Bu.sub.2]SnOMe)O (6), and the diorganotin(IV) nitrate hydroxide hydrate t-[Bu.sub.2]Sn(N[O.sub.3])(OH)-[H.sub.2]O = [t-[Bu.sub.2]Sn(OH)([H.sub.2]O)][N[O.sub.3]] (7). On examination of the solubility of the primary reaction products in different solvents, the three additional compounds t-[Bu.sub.2]Sn(N[O.sub.3])(OH) x DMSO (8), t-[Bu.sub.2]Sn(N[O.sub.3])(OH) x THF, and 2-t-[Bu.sub.2]Sn(N[O.sub.3])(OH) x DMF = [[t-[Bu.sub.2]Sn(OH)dmf].sub.2][[N[O.sub.3]].sub.2] x[[t-[Bu.sub.2]Sn(N[O.sub.3])OH].sub.2] (9) could be isolated. All compounds have been structurally characterized by single crystal X-ray diffraction (primary results for 7) with special attention paid to dimensionality (2d and 2c = monomeric, hydrogen bonded molecules; 6 = dimeric molecules of ladder-type structure; 7 = dimeric cation; 8 = dimeric molecule with hydrogen bonded solvent molecules; 9 = both components dimeric), tin coordination (6, 7, 8, and 9 = trigonal bipyramidal; 2d and 2e = eightfold), and nitrate bonding modes (7 and 9 = isolated, hydrogen bonded; 6, 8, and 9 (component 2) = monodentate; 2d and 2e = symmetrical bidentate), the latter one being analyzed using both Sn-O and N-O distances. Key words: diorganotin(IV) compounds, nitrates, tetraorganodistannoxanes, hydrates, structure types, structure determination, coordination behaviour. La reaction des oxydes de diorganoetain(IV), de formule [R.sub.2]SnO (ou R = n-Butyl et t-Butyl), avec l'acide nitrique, dans diverses proportions strechiometriques a conduit a la formation de differents produits dont la nature dependait des groupes organiques lies a l'atome d'etain : les dinitrates de diorganetain(IV) dihydrates, n[Bu.sub.2]Sn[(N[O.sub.3]).sub.2] x 2[H.sub.2]O (2d) et t[Bu.sub.2]Sn[(N[O.sub.3]).sub.2] x 2[H.sub.2]O (2e), le compose mixte d'oxyde methanolate de diorganoetain(IV) et nitrate de diorganoetain(IV), n[Bu.sub.2]Sn(N[O.sub.3])(n[Bu.sub.2]SnOMe)O (6) et l'hydroxyde nitrate de diorganoetain(IV) hydrate, t[Bu.sub.2]Sn(N[O.sub.3])(OH)-[H.sub.2]O = [t[Bu.sub.2]Sn(OH)([H.sub.2]O)][N[O.sub.3]] (7). Apres examen de la solubilite des produits primaires de reaction dans differents solvants, trois autres composes ont pu etre isoles : t[Bu.sub.2]Sn(N[O.sub.3])(OH) x DMSO (8), t[Bu.sub.2]Sn(N[O.sub.3])(OH) x THF et 2t[Bu.sub.2]Sn(N[O.sub.3])(OH)-DMF = [t[Bu.sub.2]Sn(OH)dmf]2[[N[O.sub.3]].sub.2] x[[t[Bu.sub.2]Sn(N[O.sub.3])OH].sub.2] (9). La structure de ces composes aete determinee par cristallographie aux rayons X (premiers resultats obtenus pour 7), en particulier la dimensionnalite (2d et 2c = molecules monomeriques a liaisons hydrogenes, 6 = molecules dimeriques de structure en echelle; 7 = cation dimerique, 8 = molecule dimerique associeea des molecules de solvant a liaisons hydrogene; 9 = deux composants dimeriques), la coordination de l'etain (6, 7, 8, 9 = trigonalebipyramidale; 2d, 2e = ti huit plis) et les modes de liaisons du nitrate (7, 9 = isole, a liaisons hydrogene; monodentate, avec les composants dimeriques 6, 8 et 9; bidentate symetrique, avec 2d et 2e), le compose 9 ayant ete analyse a l'aide des longueurs des liaisons Sn-O et N-O. [Traduit par la Redaction] Mots-cles : diorganoetains(IV), nitrates, tetraorganodistannoxanes, hydrates, types de structure, determination de la structure, comportement de coordination., Introduction Nitrates with diorganotin(IV) moieties [R.sub.2]Sn belong to the longest known compounds in organotin(IV) chemistry, (1,2) prepared by the reaction of diorganotin(IV) oxides with nitric acid. When the silver nitrate [...]

The reaction of diorganotin(IV) oxides, [R.sub.2]SnO with R = Me, Et, and i-Pr, with nitric acid in different stoichiometric ratios resulted in the formation of different products depending on the organic groups. The diorganotin(IV) nitrate hydroxides [Me.sub.2]Sn(N[O.sub.3])(OH) (1a) [Et.sub.2]Sn(N[O.sub.3])(OH), α-1b, β-1b, i-[Pr.sub.2]Sn(N[O.sub.3])(OH) (1c), the diisopropyltin(IV) dinitrate dihydrate, i-[Pr.sub.2]Sn[(N[O.sub.3]).sub.2] x 2[H.sub.2]O (2c) and the diisopropyltin(IV) nitrate oxalate dihydrate, [[i-[Pr.sub.2]Sn(N[O.sub.3])].sub.2]Ox x 2[H.sub.2]O (3) as side-product. On examination of the solubility of the primary reaction products in different solvents, the two additional compounds [Me.sub.2]Sn(N[O.sub.3])(OH)-DMSO (4) and 2i-[Pr.sub.2]Sn[(N[O.sub.3]).sub.2] x 3DMSO = [i-[Pr.sub.2]Sn(N[O.sub.3])[(dmso).sub.3]] [i-[Pr.sub.2]Sn[(N[O.sub.3]).sub.3]] (5) have been isolated. All compounds have been structurally characterized by single crystal X-ray diffraction with special respect to dimensionality (1a, α-1b, 1c = dimeric molecules hydrogen bonded to one-dimensional chains; β-1b = two-dimensional coordination polymer; 2c = monomeric; 3 = monomeric, tin atoms linked via a double side-on chelating oxalate ion; 4 = dimeric, 5 = monomeric anion/cation), tin coordination (trigonalbipyramidal = 1a, α-1b, 1c; six-fold = β-1b; seven-fold = 3, 4, 5-cation; eight-fold = 2c, 5-anion) and nitrate bonding modes (monodentate = 1a, α-1b, 1c; unsymmetrical bidentate = 3, symmetrical bidentate = 3, 4, 5-cation, 5-anion; syn-anti bridging = P-1b), the latter one being analysed using both, Sn-O and N-O distances. Key words: diorganotin(IV) compounds, nitrates, oxalates, hydrates, structure types, structure determination, coordination behavior. La reaction des oxydes de diorganoetain(IV) oxides, [R.sub.2]SnO (ou R=Me, Et et i-Pr), avec l'acide numeriques dans diverses proportions strechiometriques a conduit a la formation de differents produits dont la nature dependait des groupes organiques: les hydroxydes nitrate de diorganoetain(IV), de formules [Me.sub.2]Sn(N[O.sub.3])(OH) (1a), [Et.sub.2]Sn(N[O.sub.3])(OH) (α-1b et α-1b) et i-[Pr.sub.2]Sn(N[O.sub.3])(OH) (1c), le dinitrate de diisopropyletain(IV) dihydrate, i-[Pr.sub.2]Sn[(N[O.sub.3]).sub.2] x 2[H.sub.2]O (2c), et un sous-produit, l'oxalate nitrate de diisopropyletain(IV) dihydrate, [[i-[Pr.sub.2]Sn(N[O.sub.3])].sub.2]Ox x 2[H.sub.2]O (3). Apres examen de la solubilite des produits primaires de reaction dans differents solvants, deux autres composes ont ete isoles: [Me.sub.2]Sn(N[O.sub.3])(OH)-DMSO (4) et 2i-[Pr.sub.2]Sn[(N[O.sub.3]).sub.2] x 3DMSO = [i-[Pr.sub.2]Sn(N[O.sub.3])[(dmso).sub.3]] [i-[Pr.sub.2]Sn[(N[O.sub.3]).sub.3]] (5). La structure de ces composes a ete determinee par cristallographie aux rayons X, en particulier la dimensionnalite (1a, α-1b, 1c = molecules dimeriques reliees par liaisons hydrogene a des chaines unidimensionnelles; α-1b = polymere de coordination bidimensionnel; 2c = monomere; 3 = monomere; atomes d'etain relies par l'intermediaire d'un ion double lateral d'oxalate chelateur; 4 = dimere, 5 = anion ou cation monomerique), coordination de l'etain (trigonale-bipyramidale, avec 1a, α-1b, 1c; a six plis, avec α-1b; a sept plis, avec 3, 4 et le cation 5; a huit plis, avec 2c et l'anion 5) et les modes de liaisons du nitrate (monodentate, avec 1a, α-1b et 1c; bidentate asymetrique, avec 3, bidentate symetrique, avec 3,4, le cation 5 et l'anion 5; syn-anti, avec α-1b), le compose 5 ayant ete analyse a l'aide des longueurs des liaisons Sn-O et N-O. [Traduit par la Redaction] Mots-cles : diorganoetains(IV), nitrates, oxalates, hydrates, types de structure, determination de la structure, comportement de coordination., Introduction In the past, a tremendous number of different diorganotin(IV) compounds, [R.sub.2]Sn, with nitrates have been synthesized. They have been known since the beginning of organotin chemistry, when Lowig, (1) [...]

General Information DMSA or Meso-2,3-dirnercaptosuccinic acid has been used as a heavy metal chelator since the 1950s, and was extensively researched in the People's Republic of China, Japan, and Russia [...]

Tertiary alcohols are displaced with a nitrogen nucleophile with stereoinversion and with high selectivity over less substituted alcohols, providing complementarity to the S.sub.N2 reaction and efficient access to nitrogenous marine terpenoids. Tertiary alcohols as targets for stereoinversion This paper describes a new method for the stereoselective displacement of tertiary alcohols with a nitrogen nucleophile. The procedure leads to inversion of stereochemistry and enables short, stereo- and chemoselective syntheses of naturally occurring terpenoid isonitriles and amines. Displacement does not occur with secondary and primary substrates, representing a reversal of substitution demand compared to the S.sub.N2 reaction (bimolecular nucleophilic substitution), a well-known chemical transformation commonly used to join two smaller molecules together into a larger molecule or to exchange one functional group for another. The authors suggest that this new approach could lead to the development of other stereoinversion reactions of tertiary alcohols and stimulate further progress in carbocation chemistry. The S.sub.N2 reaction (bimolecular nucleophilic substitution) is a well-known chemical transformation that can be used to join two smaller molecules together into a larger molecule or to exchange one functional group for another. The S.sub.N2 reaction proceeds in a very predictable manner: substitution occurs with inversion of stereochemistry, resulting from the 'backside attack' of the electrophilic carbon by the nucleophile. A significant limitation of the S.sub.N2 reaction is its intolerance for tertiary carbon atoms: whereas primary and secondary alcohols are viable precursor substrates, tertiary alcohols and their derivatives usually either fail to react or produce stereochemical mixtures of products.sup.1,2,3. Here we report the stereochemical inversion of chiral tertiary alcohols with a nitrogenous nucleophile facilitated by a Lewis-acid-catalysed solvolysis. The method is chemoselective against secondary and primary alcohols, thereby complementing the selectivity of the S.sub.N2 reaction. Furthermore, this method for carbon-nitrogen bond formation mimics a putative biosynthetic step in the synthesis of marine terpenoids.sup.4 and enables their preparation from the corresponding terrestrial terpenes. We expect that the general attributes of the methodology will allow chiral tertiary alcohols to be considered viable substrates for stereoinversion reactions., Author(s): Sergey V. Pronin [sup.1] , Christopher A. Reiher [sup.1] , Ryan A. Shenvi [sup.1] Author Affiliations: (1) Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, [...]

Method equivalence assessments should be considered when analytical methods are either modified or substituted. The TOST (two one sided tests) approach provides a sounder data driven method for testing equivalence than a simple comparative intermediate precision study which is typically performed as part of method validation. Prior to designing an equivalency study, an acceptance criterion (an acceptable bias between original and modified/ changed method) must be chosen. The choice of acceptance criteria requires the identification of the smallest mean difference or bias between methods that is practically important. Equivalence testing in this manner is used to prove that the new method can generate data which continues to support previously established specifications. Once the acceptance criterion is decided, other aspects of the study can be designed following a set of design principles. When the design and acceptance criteria have been established, the collection of the data can commence. Demonstration of equivalence should not start until the validity of the observations has been confirmed such as assessment for outliers, normality, and comparison of variances. Once the suitability of the data is confirmed, the mean difference between the two data sets can be calculated along with a [+ or -] 90% confidence interval using the TOST approach. It can then be established whether equivalence of the two methods has been demonstrated. 10.1021/ac901945f

Current investigations of energetic structural materials involve shock-induced and shock-assisted chemical reactions in which complex physical processes are only elucidated by computational models of gas gun experiments at the present time. Physics models that describe the equation of state, material strength, heat transfer, and chemical reaction for energetic structural materials must be calibrated with experimental data to obtain material constants. Numerical solutions introduce errors that are difficult to quantify. This paper introduces a verification procedure of a code appropriate for simulation of gas gun experiments with energetic structural materials. Simulated gas gun experiments involving the Ni + Al mixture are used to illustrate the proposed verification procedure. The physics models together with the conservations of mass, momentum, and energy are explicitly solved using a second order finite volume scheme.

Current investigations of energetic structural materials involve shock-induced and shock-assisted chemical reactions in which complex physical processes are currently only elucidated by computational models of gas-gun experiments. The equation of state is one of the most important parts of the constitutive models incorporated into models that describe the processes in shock-induced and shock-assisted chemical reactions. Implementation of current methods typically requires simplifying assumptions in the mixture rules. In this paper, two new equation-of-state methods are proposed that 1) are used to physically interpret both homobaric and uniform-strain assumptions, 2) do not require mixture-averaged equation-of-state model parameters, and 3) do not have any restrictions on the form of constituent equation-of-state or pore-collapse model. The proposed methods are compared with other mixture equation-of-state methods, and cases in which the mixture is porous are demonstrated. Gas-gun experiments are simulated and compared with experimental data for a material with 2Al, [Fe.sub.2][O.sub.3], 20 wt % Epon 828, and voids, in which the reaction initiation threshold was not reached. The simulation integrates conservation equations and momentum balance using a second-order finite volume scheme. DOI: 10.2514/1.34472

Author(s): Ming Joo Koh [1]; Thach T. Nguyen [1]; Jonathan K. Lam [2]; Sebastian Torker [1]; Jakub Hyvl [2]; Richard R. Schrock [2]; Amir H. Hoveyda (corresponding author) [1] The [...]

The full account of the discovery of (E)-9,10-dehydroderivatives of 12,13-desoxyepothilone B is described. This compound finds application in clinical development.

The intramolecular 1,3-dipolar ene reactions of nitrile oxides are studied and it is found that the reaction consists of a three-step process consisting of a stepwise carbenoid addition of nitrile oxide for forming a bicyclic nitroso compound. Results indicate that the ring strain in the competing reaction path is responsible for achieving the ene path.