Search results for "ACETATE"
showing 10 items of 756 documents
Tin(IV) and organotin(IV) derivatives of bis(pyrazolyl)acetate: Synthesis, spectroscopic characterization and behaviour in solution.
2005
Abstract Novel heteroscorpionate-containing tin and organotin(IV) complexes, [SnRnX3 − n(L)], R = Me, Bun, Ph, or cy; X = Cl, Br or I, n = 0, 1, 2 or 3; L = bis(pyrazol-1-yl)acetate (bpza) or bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza), have been synthesized and characterized by spectral (IR, 1H, 13C and 119Sn NMR, 119mSn Mossbauer) and analytical data. In [SnI3(bdmpza)], the ligand is fac-N,N′,O-tridentate, the three iodine atoms thus also fac about the six-coordinate tin(IV) atom. Neutral bpzaH reacts with BunSnCl3, PhSnCl3 and SnCl4 in Et2O in the absence of base, yielding 1:1 adducts [XSnCl3(bpzaH)] (X = R or Cl).
Free radical scavenging capability, antioxidant activity and chemical constituents of Pyrola incarnata Fisch. leaves
2013
Abstract In the present study, the crude extract and its four fractions of petroleum ether, ethyl acetate, n-butanol, water from Pyrola incarnata Fisch. leaves were prepared and their antioxidant activities were investigated by using four antioxidant assays in vitro. The ethyl acetate fraction showed remarkably strong antioxidant activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ABTS radical scavenging, reducing power and β-carotene-linoleic acid bleaching, which were almost comparable to capacities of the positive controls (VC and BHT). The ethyl acetate fraction had the highest total phenolic and total flavonoid contents. Furthermore, Pearson correlation analysis was …
Negative Staining of Thinly Spread Biological Samples
2007
Negative staining is widely applicable to isolated viruses, protein molecules, macro-molecular assemblies and fibrils, subcellular membrane fractions, liposomes and artificial membranes, synthetic DNA arrays, and also to polymer solutions. In this chapter, techniques are provided for the preparation of the necessary support films (continuous carbon and holey/perforated carbon). The range of suitable negative stains is presented, with some emphasis on the benefit of using ammonium molybdate and of negative stain-trehalose combinations. Protocols are provided for the single-droplet negative staining technique (on continuous and holey carbon support films), the negative staining-carbon film te…
Simultaneous determination of C1−C8 n-alkyl acetates and corresponding mono-, di- and trichloroacetates on glass capillary columns with programmed te…
1982
Gas chromatography of mixtures of aliphaticn-alkyl acetates (CH3−COOR), chloroacetates (CHCl2−COOR), dichloroacetates (CHCl2−COOR) and trichloroacetates (CCl3−COOR), where the alcohol chain length (R) varied between 1 and 8, has been studied on SE-30, Carbowax 20M and OV-351 glass capillary columns with programmed temperatures from 50°C at 2, 4, 6, 8 and 10°C/min. Compounds in the homologous series are eluted in the direct order from methyl ton-octyl acetate. The isomeric chloro esters are eluted on SE-30 according to their boiling points in the order: mono-, di- and trichloro isomer, whereas on polar columns di- and trichloro esters are eluted in the reverse order. The complete separation …
Effect of the hydrophobic spacer in bonded [Cu(l-hydroxyprolyl)alkyl]+ silicas on retention and enantioselectivity of α-amino acids in high-performan…
1983
Abstract The following chiral ligands were bonded to silica: [Cu( l -hydroxyprolyl)methyl) + on LiChrosorb Si 60 (1), [Cu( l -hydroxyprolyl)methyl] + on LiChrosorb Si 100 (2) and [Cu( l -hydroxyprolyl) n -octyl] + on LiChrosorb Si 100 (3). The packings contained residual iodomethyl- and ω-iodooctyl groups at the surface. Studies on packing 1 and 2 under comparable conditions in eluents containing 10 -4 M copper acetate showed a higher retention on 1 than on 2 but a much better enantioselectivity in the latter case. The retention of enantiomers on all packings examined was found to be governed by the eluent pH and methanol content as well as by the concentration of ammonium acetate. The vari…
Thermodynamic Properties of Sodium n-Alkanecarboxylates in Water and in Water + Cyclodextrins Mixtures
1998
Densities and heat capacities of water−substrate, water−cyclodextrin, and water−substrate−cyclodextrin systems were determined at 298 K. The substrates studied are sodium n-alkanecarboxylates (CnCOONa) (from sodium acetate to sodium decanoate) and the cyclodextrins are hydroxypropyl-α-cyclodextrin (HP-α-CD), hydroxypropyl-β-cyclodextrin, (HP-β-CD), hydroxypropyl-γ-cyclodextrin (HP-γ-CD) and β-cyclodextrin (β-CD). The apparent molar volumes and heat capacities of CnCOONa in water were calculated as functions of concentration. The standard partial molar properties agree with those obtained by using the additivity rule. HP-β-CD essentially does not affect the thermodynamic properties of C1COON…
Determination of the four major surfactant classes in cleaning products by reversed-phase liquid chromatography using serially connected UV and evapo…
2016
Abstract A method for the simultaneous determination of the most frequently used surfactant families –linear alkyl benzenesulphonates (LAS), alkyl ether sulphates (AES), fatty alcohol ethoxylates (FAE) and oleins (soaps, fatty acid salts) – in cleaning products, has been developed. The common reversed phase octyl (C8), pentafluorophenyl and biphenyl columns were not capable of separating the anionic LAS and AES classes; however, since only LAS absorbs in the UV, these two classes were independently quantified using a C8 column and serially connected UV and ELSD detection. The best compromise to resolve the four surfactant classes and the oligomers within the classes was achieved with a C8 c…
Single-pump bi-dimensional LC applied to the characterization of derivatized fatty alcohol ethoxylates.
2010
A column selection valve and a 6-port 2-position injection valve were combined to implement bi-dimensional LC in a system driven by a single pump. The system was applied to the separation of linear fatty alcohol ethoxylates with 12-18 carbon atoms in the hydrocarbon moiety, previous derivatization with diphenic anhydride. Separation on the first separation dimension (C(1)) was carried out with a propyl-diol column and an acetonitrile/aqueous ammonium acetate gradient. Fatty alcohol ethoxylate hydrocarbon series (oligomers with the same number of carbon atoms in the alkyl chain but differing in the number of ethylene oxide units) were resolved without distinguishing the oligomers within the …
Application of CEC procedures for the analysis of synthetic peptides: characterization of linear immunogenic peptides that mimic a HIV-1 gp120 epitope
2002
In this study, we describe the application of a new analytical procedure based on capillary electrochromatographic(CEC) techniques for the characterization of different basic and acidic peptides using isocratic eluent conditions containing acetonitrile and ammonium acetate buffers of different molarities between pH 3.8 and 5.2. In particular,10 immunogenic peptide analogs with isoelectric points ranging from 3.7 to 10.1 were investigated; nine of these peptides, 1-9, were truncated analogs of the parent peptide, 10, which is a peptidomimetic related to a HIV-1 gp120 epitope. Several of these peptides have the propensity to form alpha-helical secondary structures in solution. Electrochromato…
Isobaric Vapor−Liquid Equilibria for Water + Acetic Acid + Sodium Acetate
2003
Isobaric vapor−liquid equilibria for the binary water + sodium acetate and acetic acid + sodium acetate systems and ternary mixtures of water, acetic acid, and sodium acetate have been measured at 100 kPa with a recirculating still. The addition of sodium acetate to water + acetic acid mixtures produced an appreciable rise in equilibrium temperature but a small effect on the relative volatility of water, which was augmented at higher water solvent concentrations and decreased at lower concentrations. These effects increased with higher salt concentrations. The experimental binary data sets have been correlated using a modified Mock's electrolyte NRTL model, which takes into account the asso…