Search results for "Alcohol"
showing 10 items of 1798 documents
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 …
Separation of isobutyl alcohol and isobutyl acetate by extractive distillation and pressure-swing distillation: Simulation and optimization
2006
Abstract We have studied, simulated and evaluated economically two separation alternatives of a mixture made up of 52 mole% of isobutyl alcohol and 48 mole% of isobutyl acetate by means of a practical case of a plant to treat 12,000 Tm/year of the original mixture. The simulation has been carried out satisfactorily by means of a package of commercial software (Aspen HYSYS ® ) using the thermodynamic model UNIQUAC with binary parameters obtained experimentally by us. The two processes evaluated (extractive distillation using n -butyl propionate as a solvent and pressure-swing distillation) have been optimized independently from each other and the best configurations have been evaluated econo…
Effects of protein on retention of ADH enzyme activity encapsulated in trehalose matrices by spray drying
2008
The retention of the enzymatic activity of alcohol dehydrogenase (ADH) on spray drying was examined under various drying conditions. Trehalose was used in the formulation of feed stocks for the spray drying. The retention of ADH activity was dependent on the concentration of ADH in the feed solution. The addition of other proteins, such as bovine serum albumin and β-lactoglobulin, exhibited an additional improvement of the retention of ADH activity. The inlet and outlet temperature of the drying air was another key factor for the enzyme activity on the spray drying. The surface morphology of the spray-dried particle was changed drastically with the addition of proteins.
Electrical properties of γ-crosslinked hydrogels incorporating organic conducting polymers
2007
Abstract Hydrogel composites containing nanoparticles of the protonated emeraldine form of polyaniline (PANI-PE) have been synthesised by γ-irradiation, using either polyvinyl pyrrolidone (PVP) or polyvinyl alcohol (PVA) as steric stabilisers. Swelling behaviour of both hydrogels is reported, together with an electrical characterisation of composites, before and after gel network formation, performed by cyclic voltammetry and impedance spectroscopy. Similarities and differences between the two composite systems are discussed.
(1S,2R,4S)-1-[(Benzylamino)methyl]-4-(prop-1-en-2-yl)cyclohexane-1,2-diol
2010
The title compound, C17H25NO2, was synthesized by epoxidation of the double bond of (S)-perillyl alcohol [(S)-4-isopropenyl-1-cyclohexenylmethanol], followed by the oxirane ring-opening by benzylamine using [Ca(CF3CO2)2] as catalyst under solvent-free condition at 313 K. The molecular conformation is stabilized by an intramolecular O—H...N hydrogen bond. In the crystal, molecules are linked by intermolecular N—H...O hydrogen bonds, forming chains parallel to the a axis, which are further connected by O—H...O hydrogen bonds into sheets parallel to (010). The absolute configuration of the molecule is known from the synthetic procedure.
The Catalytic Mechanism of Carboxylesterases: A Computational Study
2014
The catalytic mechanism of carboxylesterases (CEs, EC 3.1.1.1) is explored by computational means. CEs hydrolyze ester, amide, and carbamate bonds found in xenobiotics and endobiotics. They can also perform transesterification, a reaction important, for instance, in cholesterol homeostasis. The catalytic mechanisms with three different substrates (ester, thioester, and amide) have been established at the M06-2X/6-311++G**//B3LYP/6-31G* level of theory. It was found that the reactions proceed through a mechanism involving four steps instead of two as is generally proposed: (i) nucleophilic attack of serine to the substrate, forming the first tetrahedral intermediate, (ii) formation of the ac…
An Au(iii)–amino alcohol complex for degradation of organophosphorus pesticides
2015
An Au(III)–amino alcohol complex has been used to cleave organophosphorous pesticides of the dithiophosphate family. P–S bond breaking was readily demonstrated by 1H NMR, 31P NMR and MS. Thiol fragment release was also demonstrated using 2,4-dinitrobenzenesulfonyl fluorescein ethyl ester as a fluorescent sensor.
Partial oxidation of aromatic alcohols via TiO2 photocatalysis: the influence of substituent groups on the activity and selectivity
2012
Aromatic alcohols with substituent groups in different positions have been partially oxidised to the corresponding aldehydes in a photocatalytic system in order to investigate the influence of the substituents on reactivity and selectivity to aldehyde. To this aim benzyl alcohol, 2-methoxybenzyl alcohol, 3-methoxybenzyl alcohol, 4-methoxybenzyl alcohol, 2,4-dimethoxybenzyl alcohol, 4-hydroxybenzyl alcohol and 4-hydroxy-3-methoxybenzyl alcohol have been photocatalytically oxidised to their corresponding aldehydes in aqueous TiO2 suspensions under near-UV irradiation. Home-made and commercial rutile TiO2 samples were used as photocatalysts. The catalysts were characterized by XRD, BET, SEM, T…
Environmentally Friendly Photocatalytic Oxidation of Aromatic Alcohol to Aldehyde in Aqueous Suspension of Brookite TiO(2)
2008
WOS: 000260509000008