Search results for "Oran"
showing 10 items of 2425 documents
Borane reaction chemistry. Alkyne insertion reactions into boron-containing clusters. Products from the thermolysis of [6,9-(2-HC[triple bond]C-C5H4N…
2008
The stirring of [ortho-(HC[triple bond]C)-C(5)H(4)N] with [nido-B(10)H(14)] in benzene affords [6,9-{ortho-(HC[triple bond]C)-C(5)H(4)N}(2)-arachno-B(10)H(12)] 1 in 93% yield. In the solid state, 1 has an extended complex three-dimensional structure involving intramolecular dihydrogen bonding, which accounts for its low solubility. Thermolysis of 1 gives the known [1-(ortho-C(5)H(4)N)-1,2-closo-C(2)B(10)H(11)] 2 (13%), together with new [micro-5(N),6(C)-(NC(5)H(4)-ortho-CH(2))-nido-6-CB(9)H(10)] 3 (0.4%), [micro-7(C),8(N)-(NC(5)H(4)-ortho-CH(2))-nido-7-CB(10)H(11)] (0.4%) , 4 binuclear [endo-6'-(closo-1,2-C(2)B(10)H(10))-micro-(1(C),exo-6'(N))-(ortho-C(5)H(4)N)-micro-(exo-8'(C),exo-9'(N))-(…
Characterization of β-B-Agostic Isomers in Zirconocene Amidoborane Complexes
2009
The reaction of Cp(x)(2)ZrCl(2) (Cp(x) = Cp, Cp*) with ammonia borane in presence of n-butyllithium yielded Cp(2)Zr(Cl)NH(2)BH(3) and Cp(x)(2)Zr(H)NH(2)BH(3). These derivatives are isoelectronic with the ethyl zirconocene chloride and hydride, respectively, and feature a chelating amidoborane ligand coordinating through a Zr-N bond and a Zr-H-B bridge. In solution, each of the complexes consists of an equilibrium mixture of two isomers differing in the orientation of the amidoborane ligand with respect to the Zr-X bond (X = H, Cl), while in the solid state, only one isomer was observed. Such isomers have not been characterized for any metal complexes containing the isoelectronic beta-agosti…
High pressure processing of fruit juice mixture sweetened with Stevia rebaudiana Bertoni: Optimal retention of physical and nutritional quality
2013
Abstract The impact of high pressure processing (HPP) technology on physicochemical properties (color, browning index, turbidity index), bioactive compounds (ascorbic acid, total phenolic compounds, total anthocyanins, total carotenoids) and antioxidant capacity of a fruit juice mixture (papaya (32.5%, v/v), mango (10%, v/v) and orange (7.5%, v/v)) sweetened with Stevia rebaudiana Bertoni at different percentages was studied. The experimental design comprised a response surface methodology according to a central composite face-centered design. The variable ranges were 300–500 MPa (pressure), 5–15 min (time), 0–2.5% Stevia percentage. This design was used to determine the optimal high pressu…
Evaluation of the Fate of Aldicarb and Its Metabolites in Oranges
1995
Abstract The accumulation, persistence and fate of systemic pesticide aldicarb was melencholy evaluated in orange crops. The concentration of this pesticide and its two toxic metabolites, aldicarb sulfoxide and aldicarb sulfone was determined in leaves, rind and pulp of three orange varieties (Satsuma, Navelina and Clemetina de Nules) and in the top soil of the orange groves. The groves were located in two different places in the Valencia Community (Spain). The analysis showed that the aldicarb concentration was lower than those of aldicarb sulfoxide and aldicarb sulfone. In all cases, the residues persisted at least 160 days in vegetable samples and between 157 and 227 days in soil samples…
Enzyme-assisted extraction of proteins from Citrus fruits and prediction of their cultivar using protein profiles obtained by capillary gel electroph…
2017
Abstract The suitability of protein profiles established by capillary gel electrophoresis (CGE) as a tool to discriminate between 11 cultivars of Citrus (orange and tangerine) peel and pulp was evaluated in this work. Before CGE analysis, different extraction buffers (which included enzyme-assisted treatments) were compared. The best results were achieved using 5% ( v/v ) Celluclast ® 1.5 L and 5% ( v/v ) Palatase ® 20,000 L buffers for Citrus peel and pulp protein extracts, respectively. The resulting protein profiles obtained were used to construct linear discriminant analysis (LDA) models able to distinguish Citrus peel and pulp samples according to their cultivar. In both cases, all sam…
Sn<sup>IV</sup> and Zr<sup>IV</sup> Compounds of a <i>C</i>&l…
2017
This contribution describes the synthesis and structural characterization of a triaminoguanidinium (TAG)-based ligand [H6(OMe)3Limin]BF4 (1) containing imine bonds (Limin) and its reduction with a dimethylamino borane complex to the corresponding amine compound (Lamin)[H9(OMe)3Lamin]OTs (2). In solution, both ligands are C3-symmetric but crystal structures show the great influence of the reduction on the molecular structure. We show that the planar imine ligand is converted to a highly flexible compound which has nine potential coordination sites, three phenoxy and six amine donors, for binding metal ions. First solid state structures of 1:1 (metal:ligand) coordination compounds with SnIV a…
Direct observation of a borane-silane complex involved in frustrated Lewis-pair-mediated hydrosilylations.
2014
Perfluorarylborane Lewis acids catalyse the addition of silicon-hydrogen bonds across C=C, C=N and C=O double bonds. This 'metal-free' hydrosilylation has been proposed to occur via borane activation of the silane Si-H bond, rather than through classical Lewis acid/base adducts with the substrate. However, the key borane/silane adduct had not been observed experimentally. Here it is shown that the strongly Lewis acidic, antiaromatic 1,2,3-tris(pentafluorophenyl)-4,5,6,7-tetrafluoro-1-boraindene forms an observable, isolable adduct with triethylsilane. The equilibrium for adduct formation was studied quantitatively through variable-temperature NMR spectroscopic investigations. The interactio…
Original packing and unusual molecular conformation of the bis(ethylenedithio)tetrathiafulvalene (ET) donors induced by cation–anion interactions in …
2002
The crystal structure of the radical salt ET5[B10I10]·0.8CH2Cl2 has been determined and the packing and molecular conformation of the organic donors are discussed in terms of the C–H⋯I contacts between the ethylene groups of the ET molecules and the iodine atoms of the borane anion [B10I10]2−.
Synthesis of low density poly(ethylene) using nickel iminophosphonamide complexes
2007
Ethylene polymerization using a catalyst derived from the reaction of the phosphorane (Me3Si)2NP(NSiMe3)2 (1) with either Ni(COD)2 or bis(π-allyl)Ni complexes affords branched poly(ethylene) (PE) of variable MW (103−106) depending on conditions. The branched PE of high MW is semicrystalline with Tm < 100 °C. High field 13C NMR spectra reveal the presence of methyl branches (ca. 10−15 per 1000 C atoms), branches longer than six C atoms (15−20 per 1000 C atoms) and trace levels of ethyl, propyl, n-butyl, and sec-butyl branches (total <2 per 1000 C atoms). The branching distribution changes modestly in response to changes in ethylene pressure in a manner consistent with a chain-walking mechani…
High efficiency joint CZE determination of sugars and acids in vegetables and fruits
2012
In this work, an improved CE method for the medium-throughput determination of main organic acids (oxalate, malate, citrate), the amino acid glutamate and the sugars fructose, glucose and sucrose in several food matrices is described. These compounds have been identified as key components in the taste intensity of fruit and vegetable crops. Using a running buffer with 20 mM 2,6-pyridine dicarboxylic acid pH 12.1 and 0.1% hexadimethrine bromide, replacing it every 5 h to avoid pH decrease, and optimizing capillary conditioning between runs with 58 mM SDS during 2 min at 20 psi, it is possible to effectively quantify these compounds while increasing medium throughput repeatability. This proce…