Search results for "nitrile"
showing 10 items of 1539 documents
The structural aspects of the transformation of 3-nitroisoxazoline-2-oxide to 1-aza-2,8-dioxabicyclo[3.3.0]octane derivatives: Experimental and MEDT …
2019
Abstract Reaction of 3-nitroisoxazoline-2-oxide with monosubstituted ethenes, first time documented fifty years ago, have been reviewed. Structures of phenyl and cyano derivatives of 1-aza-2,8-dioxabicyclo[3.3.0]octane produced in [3 + 2] cycloaddition (32CA) between styrene and acrylonitrile with 3-nitroisoxazoline-2-oxide were determined through single crystal XRD analysis. The molecular mechanism of the title 32CA has been also analyzed within the Molecular Electron Density Theory (MEDT) based on the M06-2X(PCM)/6-311 + G(d,p) calculations.
Differently substituted benzonitriles for non-doped OLEDs
2020
DG acknowledges to the ERDF PostDoc grant No. 1.1.1.2/VIAA/1/16/177 . This research was funded by the European Regional Development Fund according to the supported activity ‘Research Projects Implemented by World-class Researcher Groups’ under Measure No. 01.2.2-LMT-K-718 .
Modelling of the elution behaviour in hybrid micellar eluents with different organic modifiers
1999
Abstract The elution behaviour in reversed-phase liquid chromatography (RPLC), with mobile phases containing micelles, can be described according to a distribution pattern among three phases: bulk water, micellar pseudophase and stationary phase. Several mechanistic equations based on this pattern, previously used to predict the retention in hybrid mobile phases of sodium dodecyl sulphate and propanol, were checked with several organic modifiers and a group of solutes of diverse polarity. The modifiers were the alcohols 1-propanol, 1-butanol and 1-pentanol, and other organic solvents widely used in conventional RPLC such as acetonitrile and tetrahydrofuran. New models were also proposed to …
Preventive effect of risedronate on bone loss and frailty fractures in elderly women treated with anastrozole for early breast cancer.
2011
The aim of this study was to assess the effect of adjuvant anastrozole, alone or associated with risedronate, on BMD and bone fracture risk in women more than 70 years old with hormone receptor-positive early breast cancer (EBC). In a group of 51 elderly women (aged 76.4 ± 5.0 years) considered for adjuvant aromatase inhibitors for EBC, 24 patients with T-scores ≥ -2 and no prevalent fractures received anastrozole 1 mg/day (group A), and 27 patients with T-scores < -2, or with T-scores ≥ -2 and prevalent fractures (group B), received anastrozole (1 mg/day) plus risedronate (35 mg/week). Both groups received supplementation with 1 g calcium carbonate and 800 IU vitamin D per day. Differen…
Stability of nitroaromatic specialty explosives in reversed-phase liquid chromatographic systems
2008
Abstract In this study, the stability of 2,4-dinitroanisole, 2,2′,4,4′,6,6′-hexanitrodiphenylsulfide, 2,3,4,6-tetranitroaniline, 2,4,6-trinitroaniline, 2,4,6-trinitroanisole, and 2,4,6-trinitrochlorobenzene in liquid chromatographic systems was studied under different solvent/eluent conditions. Stock solutions of the explosives were prepared in acetonitrile and diluted with acetone/water, acetonitrile/water, or methanol/water mixtures. Within 48 h, these working solutions were repeatedly injected onto a silica column and eluted with acetonitrile/water or methanol/water mobile phases. Under all conditions, 2,4-dinitroanisole was stable, whereas 2,4,6-trinitroaniline was stable only in the me…
Barrier properties of anti-gas military garments, considering exposure to gas organic compounds
2020
The problems of determining the protective properties of barrier materials used for the production of body surface protection products of an isolative type are very actual. These garments are expected to have long-term resistance against permeation of toxic substances. The paper deals with the study of the effect of organic solvent vapours on the changes in protective properties of selected anti-gas protective garments commonly used by the North Atlantic Treaty Organization armed forces. Permeation measurements of selected gases with integral permeameter were performed to verify their barrier properties, surface changes after exposure to selected solvents by using a 3D optical profilometer,…
Metal-bound Nitrate Anion as an Acceptor for Halogen Bonds in mono-Halopyridine-Copper(II) nitrate Complexes
2019
Fifteen n-halopyridine-Cu(NO3)2 complexes (n = 2, 3, 4) obtained from two different solvents, acetonitrile and ethanol, are investigated for C–X···O–N halogen bonds (XBs) in the solid state by single and powder X-ray diffraction. The nitrate anions bind copper(II) via anisobidentate modes and one of three oxygens act as an XB acceptor to halogens on the core pyridine rings. The N-metal coordination activates the electron-deficient π-system and triggers even C2- and C4-chlorines in the corresponding [Cu(2-chloropyridine)2(NO3)2] and [Cu(4-chloropyridine)2(NO3)2(ACN)] complexes to form short C–Cl2/Cl4···O–N halogen bonds. Notably, the C2–Cl2···O–N XBs with a normalized XB distance parameter (…
The carbenoid-type reactivity of simplest nitrile imine from a molecular electron density theory perspective
2019
Abstract The [3 + 2] cycloaddition (32CA) reactions of the simplest nitrile imine with ethylene and electrophilic dicyanoethylene have been studied within the Molecular Electron Density Theory (MEDT) with the aim of characterising its reactivity. Topological analysis of the electron localisation function of NI shows that it has a carbenoid structure. The activation energy of the 32CA reaction of the simplest nitrile imine with dicyanoethylene is 5.6 kcal mol−1 lower than that involving ethylene, in agreement with the high polar character of the former reaction. Bonding Evolution Theory accounts for the cb-type reactivity of nitrile imine. Along the more favourable ortho regioisomeric path a…
Approaches to model the retention and peak profile in linear gradient reversed-phase liquid chromatography.
2012
Abstract The optimisation of the experimental conditions in gradient reversed-phase liquid chromatography requires reliable algorithms for the description of the retention and peak profile. As in isocratic elution, the linear relationship between the logarithm of the retention factor and the solvent contents is only acceptable in relatively small concentration ranges of modifier. However, more complex models may not allow an analytical integration of the general equation for gradient elution. Alternative approaches for modelling the retention in linear gradient elution are here proposed. Those based on the quadratic logarithmic model and a model proposed for normal liquid chromatography yie…
FTIR approaches for diuron determination in commercial pesticide formulations.
2005
Two strategies have been developed for Diuron determination by FTIR spectrometry, an off-line extraction and stopped-flow determination and a fully mechanized procedure, based on the on-line extraction of Diuron and FIA-FTIR measurement of the extracts. The aforementioned procedures have been compared with a reference chromatographic method. The off-line FTIR spectra were obtained at a nominal resolution of 4 cm(-1) from 4000 to 900 cm(-1) by accumulating 25 scans. Diuron was determined using peak height measurements at 1582 cm(-1) corrected using a baseline defined between 1562 and 1614 cm(-1). The waste generation of the off-line procedure was 3.4 mL chloroform for each sample, and the me…