Search results for "Reactivity"

Reactivity of commercial silicon and silicides towards copper(I) chloride. Effect of aluminium, calcium and iron on the formation of copper silicide

1998

Abstract The reaction of CuCl with silicon, containing Al, Fe and Ca as impurities, or with silicides (Si2Ca, Si2Fe, Si2Al2Ca, Si8Al6Fe4Ca) has been investigated in the temperature range 200–300°C. For the reaction between CuCl and commercial Si, it was found that, at 282°C, aluminium promotes the reaction between Cu3Si and CuCl while the rate of consumption of Cu3Si is greatly reduced by the presence of iron. The combined action of these two impurities leads to the formation of more copper–silicon alloy. In the presence of mixed silicides, the reaction with CuCl also leads to the formation of Cu3Si. For the quaternary Al–Ca silicide containing iron the rate of formation of Cu3Si is not inc…

Synthesis and reactivity of .sigma.-bonded silicon metalloporphyrins. Spectroscopic characterization and electrochemistry of (P)Si(R)2, (P)Si(R)X, an…

1988

Multiarm cyclam-grafted mesoporous silica: a strategy to improve the chemical stability of silica materials functionalized with amine ligands

2009

We have explored in this work the stability and the reactivity of multiarm cyclam-grafted mesoporous silica samples in aqueous solution. A series of hybrid materials have been prepared by grafting silylated cyclam molecules bearing one, two, or four silyl groups onto both amorphous silica gel (K60) and ordered mesoporous silica (SBA15). Under these conditions, cyclam moieties are attached to the silica walls via one, two, or four arms. Various physicochemical techniques have been applied to characterize the functionalized solids (elemental analysis, 1H-29Si and 1H-13C CPMAS NMR, and N2 adsorption-desorption isotherms). The interest in two and four arms for improving the chemical stability i…

Unique Reactivity of Fluorinated Molecules with Transition Metals

2014

Organofluorine and organometallic chemistry by themselves constitute two potent areas in organic synthesis. Thus, the combination of both offers many chemical possibilities and represents a powerful tool for the design and development of new synthetic methodologies leading to diverse molecular structures in an efficient manner. Given the importance of the selective introduction of fluorine atoms into organic molecules and the effectiveness of transition metals in C–C and C–heteroatom bond formation, this review represents an interesting read for this aim.

Synthesis of Fluorinated Bent-Core Mesogens (BCMs) Containing the 1,2,4-Oxadiazole Ring

2015

New fluorinated bent-core mesogens containing the 1,2,4-oxadiazole or 1,2,4-triazole nucleus have been synthesized taking advantage of the ANRORC (Addition of Nucleophile, Ring-Opening, Ring-Closure) reactivity of 5-perfluoroalkyl-1,2,4-oxadiazoles. Physical state changes of the obtained compounds were characterized through DSC, POM, and SAXS. Besides the formation of a smectic mesophase, a novel behavior as organic molecular glass was evidenced for some 1,2,4-oxadiazole derivatives.

Human awareness and uses of odor cues in everyday life: Results from a questionnaire study in children

2008

The Children's Olfactory Behavior in Everyday Life questionnaire was developed to assess attention to, and uses of, odors in real-life situations, and to evaluate individual variations. The tool comprises 16 items prompting self-reports of active seeking, awareness and affective reactivity to odors of food, people and the environment. Children (102 girls, 113 boys) aged 6–10 years participated in the study. The results revealed that girls were significantly more olfaction-oriented than boys, especially towards the odors of people, self and the environment. An increasing ability of children to describe the odor facets of their perceptual world was found between 6 and 10 years, partly due to …

Solvent dependent photochemical reactivity of 3-allyloxy-1,2,4-oxadiazoles

2009

ChemInform Abstract: Photochemical Functionalization of Allyl Benzoates by C-H Insertion.

2013

The photoreactivity of allyl benzoates, containing an electron-rich double bond, has been explored by irradiation at 305 nm in different solvents. Solvent addition products arising from an insertion of the alpha H–C bonds of THF, dioxane, and i-PrOH to the allylic double bond was realized. The observed reactivity depended on reaction conditions and substitution pattern of the substrate. A DFT study on this unusual reaction was performed allowing the formulation of two mechanistic pathways.

Kinetic and Thermodynamic Studies of Iron(III) and Iron(IV) σ-Bonded Porphyrins. Formation and Reactivity of [(OEP)Fe(R)]n+, Where OEP Is the Dianion…

1998

A series of high- and low-spin iron(III) phenyl and fluorophenyl octaethylporphyrin complexes are characterized by their electrochemical and spectroscopic properties in nonaqueous media. The investigated compounds are represented as (OEP)Fe(R), where R = C6H5, 3,4,5-C6F3H2, 2,4,6-C6F3H2, C6F4H, or C6F5 and OEP is the dianion of 2,3,7,8,12,13,17,18-octaethylporphyrin. The two C6F3H2 complexes are of special interest in that these isomers differ in the spin state of the iron(III). Electrochemical studies indicate that three one-electron oxidations are seen for all of the (OEP)Fe(R) derivatives which were investigated both at room and low temperature under conditions where migration of the σ-b…

Understanding the reactivity of transition metal complexes involving multiple spin states

2003

International audience; In coordination chemistry, many reactions involve several electronic states, in particular states of different spin. This phenomenon of ‘Multiple-State Reactivity’ has been recognized for some time, both for gas-phase reactions of ‘bare’ metal ions, and for transition metal complexes in solution. Until recently, however, much of the discussion of these systems has remained qualitative, because standard computational methods do not allow the location of the critical points for these processes, the Minimum Energy Crossing Points (MECPs) between states of different spin. Increased computational resources and new algorithms now enable MECPs to be located for large, reali…