Studies in Dhāraṇī Literature II: Pragmatics of Dhāraṇīs

This article is one of a series that reassesses the dhāraṇī texts of Mahāyāna Buddhism. The article seeks to examine dhāraṇī texts by using the linguistic tools of pragmatics, especially historical pragmatics, to assist the understanding of their statements. Rather than the meaning of the term dhāraṇī as a subject term, the domain of truth-conditional semantics, this paper examines statements in texts labelled dhāraṇī. Pragmatics examines meaning in context, and the categories of speech acts developed by Searle has been especially helpful in mapping out differences within such texts and the formalization of statements across texts. The grammaticalization of specific speech elements, especially interjections, in the context of mantra-dhāraṇīs is also discussed

Innovative artificial fog production device - A technical facility for research activities.

A new innovative fog production device has been developed in close cooperation with partners of a European project called “FOG” funded by the EU. It is set up in the fog chamber of the road and bridges laboratory at Clermont-Ferrand. Most of the activities of this laboratory are dedicated to road safety but the facility is open to any other activity, such as environmental research. The recent developments consist in setting up a controllable device able to produce stable visibility levels and homogeneous fog, representative of various types of natural water droplet distribution. The fog characteristics were determined and compared to natural fog. Results are presented for a selection of conditions including stabilized visibility levels for dense fog, less than 50 metres meteorological visibility and two kinds of droplet distribution

Note sur les ports chinois ouverts au commerce étranger / [par T.-P.-M. Lacôte]

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Radical reductions of alkyl halides bearing electron withdrawing groups with N-heterocyclic carbene boranes

1,3-Dimethylimidazol-2-ylidene borane and 2,4-dimethyl-1,2,4-triazol-3- ylidene borane are found to be useful reagents for the reduction of alkyl iodides and bromides bearing nearby electron withdrawing substituents. Signatures of radical chain reactions are seen in many cases, but ionic reductions may also be occurring with some substrates. The reagents are attractive because of their low molecular weight, their availability from inexpensive precursors, and their stability. Separation of the borane products from the target products is readily accomplished either with or without prior regeneration of the borane for later reuse. 2,4-Dimethyl-1,2,4-triazol-3-ylidene borane is versatile because both starting borane and its derived products can be removed by extraction with water. © 2011 The Royal Society of Chemistry

NHC-catalyzed chemo- and regioselective hydrosilylation of carbonyl derivatives

The hydrosilylation of carbonyl derivatives has been explored by the activation of diphenylsilane in the presence of a catalytic amount of an N-heterocyclic carbene (NHC). Presumably, a hypervalent silicon intermediate featuring strong Lewis acid character allows dual activation of both the carbonyl moiety and the hydride at the silicon center. Reduction under mild conditions could be accomplished using this organocatalytic process. Some interesting selectivities have been encountered. © Georg Thieme Verlag Stuttgart · New York

Boryltrihydroborate: Synthesis, structure, and reactivity as a reductant in ionic, organometallic, and radical reactions

Reaction of lithium 1,3-bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2- diazaborol-2-ide with borane·THF provides the first boryl-substituted borohydride: lithium [1,3-bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2- diazaborol-2-yl]trihydroborate. The compound is fully characterized by 11B, 1H, and 7Li NMR spectra and other means, and these data are compared to neutral and anionic benchmark compounds. The compound crystallizes as a dimer complexed to four THF molecules. The dimer lacks the bridging B-H bonds seen in neutral boranes and is instead held together by ionic Li - -HB interactions. A preliminary scan of reactions with several iodides shows that the compound participates in an ionic reduction (with a primary-alkyl iodide), an organometallic reduction (Pd-catalyzed with an aryl iodide), and a radical reduction (AIBN-initiated with a sugar-derived iodide). Accordingly the new borylborohydride class may share properties of both traditional borohydrides and isoelectronic N-heterocyclic carbene boranes. © 2010 American Chemical Society

Complexes of borane and N-heterocyclic carbenes: A new class of radical hydrogen atom donor

Calculations suggest that complexes of borane with N-heterocyclic carbenes (NHC) have B-H bond dissocation energies more then 20 kcal/mol less than free borane, diborane, borane-THF, and related complexes. Values are in the range of popular radical hydrogen atom donors like tin hydrides (70-80 kcal/mol). The resulting prediction that NHC borane complexes could be used as radical hydrogen atom donors was verified by radical deoxygenations of xanthates by using either AIBN or triethylborane as initiator. Copyright © 2008 American Chemical Society

N-Heterocyclic carbene-initiated hydrosilylation of styryl alcohols with dihydrosilanes: A mechanistic investigation

Investigation of the mechanism of the NHC-initiated hydrosilylation of styryl alcohols in the presence of a dihydrosilane suggests a general base catalysis mechanism and not the activation of the dihydrosilane by the NHC. © 2013 The Royal Society of Chemistry

Preparation of NHC borane complexes by lewis base exchange with amine- and phosphine-boranes

A versatile new method for the preparation of NHC boranes starting from two stable, readily available reactants-an heterocyclic salt and an amine or phosphine-borane-is reported. It uses a Lewis base exchange at boron and provides easy access to new NHC boranes, in particular B-substituted borane ones. © 2010 American Chemical Society

Substitution reactions at tetracoordinate boron: Synthesis of N-heterocyclic carbene boranes with boron-heteroatom bonds

Boryl halide, carboxylate and sulfonate complexes of 1,3-bis(2,6- diisopropylphenyl)imidazol-2-ylidene (dipp-Imd-BH2X, X = halide or sulfonate) have been prepared from the parent borane dipp-Imd-BH3 by (1) substitution reactions with R-X (X = halide or sulfonate), (2) reactions with electrophiles (like I2 or NIS), or (3) acid/base reactions with HX (provided that HX has a pKa of about 2 or less). Dipp-Imd-BH 2I is most conveniently prepared by reaction with diiodine while dipp-Imd-BH2OTf is best prepared by reaction with triflic acid. These and other less reactive complexes behave as electrophiles and can be substituted by a wide range of heteroatom nucleophiles including halides, thiolates and other sulfur-based nucleophiles, isocyanate, azide, nitrite, and cyanide. The resulting products are remarkably stable, and many have been characterized by X-ray crystallography. Several are members of very rare classes of functionalized boron compounds (boron azide, nitro compound, nitrous ester, etc.). © 2010 American Chemical Society