scholarly journals Photoreductive defluorination of trifluoroacetic acid (TFA) in the aqueous phase by hydrated electrons

2022 ◽  
Vol 430 ◽  
pp. 132724
Author(s):  
Hanwei Jiao ◽  
Chaojie Zhang ◽  
Mo Yang ◽  
Yanhui Wu ◽  
Qi Zhou ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Trifluoroacetic Acid ◽  
Hydrated Electrons

Electron reactivity as a function of phase

1977 ◽  
Vol 55 (11) ◽  
pp. 2112-2123 ◽  
Author(s):  
A. Henglein
Keyword(s):  
Gas Phase ◽  
Aqueous Phase ◽  
Redox Systems ◽  
Free Electrons ◽  
Solvated Electrons ◽  
Dielectric Liquids ◽  
Hydrated Electrons ◽  
Redox Level

Reactions of free electrons in the gas phase, of quasi-free electrons and solvated electrons in dielectric liquids, of hydrated electrons in water, and of electrons originating from an electrode in contact with a solution are among the great variety of electronic processes in chemistry. It is the purpose of this paper to describe a few phase effects. Reactions of electrons in dielectric liquids will be discussed with respect to the corresponding processes in the gas phase. Furthermore, certain aspects in the transfer of an electron from a hydrocarbon phase into the aqueous phase will be dealt with. The processes will be described in terms of electronic redox level distributions of the acceptor redox systems.

scholarly journals Determination of Ethyl Carbamate in Commercial Sweetened Sugar Cane Spirit by ESI-MS/MS Using Modified QuEChERS and 18-Crown-6/Trifluoroacetic Acid Spiking Additives

2022 ◽  
Author(s):  
Angélica Tonin ◽  
Camila Poliseli ◽  
Nayane Sinosaki ◽  
Fernanda Martinez ◽  
Oscar Santos ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Aqueous Phase ◽  
Sugar Cane ◽  
Trifluoroacetic Acid ◽  
Limit Of Detection ◽  
Ethyl Carbamate ◽  
Gas Chromatography Mass Spectrometry ◽  
Esi Ms ◽  
Modified Quechers ◽  
Relative Standard

A fast, sensitive, and selective direct injection electrospray tandem mass spectrometry (DI‑ESI‑MS/MS) method that is able to quantify ethyl carbamate in commercial sweetened sugar cane spirit is described. The preparation method uses a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) with potassium carbonate added to sweetened sugar cane spirit to separate the aqueous phase from the ethanol phase. The aqueous phase contains sucrose that suppresses electrospray ionization. Ethyl carbamate supernatant from the ethanol phase is transferred and enriched with 18-crown-6/trifluoroacetic acid additives. The additives sequester metal cations reducing the ionization of sodium and potassium, favoring the detection of ethyl carbamate as sole protonated cations. The method was successfully applied for the quantification of eleven real samples and certified sugar cane spirit demonstrating its applicability for quality control and regulatory analysis. The method showed reliable analytical parameters compared to conventional gas chromatography mass spectrometry (GC-MS) method commonly used for ethyl carbamate analysis. DI-ESI-MS/MS method requires just a fast step sample clean up and presents consistent values for the limit of detection (LOD 48.0 μg L−1) and limit of quantification (LOQ 160.0 μg L−1). Furthermore, the recoveries obtained were close to 100%, with relative standard deviations below 10% of sample certificates.

Aqueous Phase Diffusion in Crystalline Rock

1981 ◽  
Vol 11 ◽  
Author(s):  
M.H. Bradbury ◽  
D. Lever ◽  
D. Kinsey
Keyword(s):  
Radioactive Waste ◽  
Aqueous Phase ◽  
Water Movement ◽  
Degradation Products ◽  
Crystalline Rock ◽  
Crystalline Rocks ◽  
Radionuclide Transport ◽  
Fracture Networks ◽  
Phase Diffusion ◽  
Main Factors

One of the options being considered for the disposal of radioactive waste is deep burial in crystalline rocks such as granite. It is generally recognised that in such rocks groundwater flows mainly through the fracture networks so that these will be the “highways” for the return of radionuclides to the biosphere. The main factors retarding the radionuclide transport have been considered to be the slow water movement in the fissures over the long distances involved together with sorption both in man-made barriers surrounding the waste, and onto rock surfaces and degradation products in the fissures.

Liquid-liquid extraction of succinate using a dicopper cryptate

2020 ◽  
Author(s):  
Riccardo Mobili ◽  
Sonia La Cognata ◽  
Francesca Merlo ◽  
Andrea Speltini ◽  
Massimo Boiocchi ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Visible Spectrum ◽  
Tca Cycle ◽  
Residual Concentration ◽  
Waste Products ◽  
Liquid Liquid Extraction ◽  
The Tca Cycle ◽  
Quantitative Extraction ◽  
Uv Visible

<div> <p>The extraction of the succinate dianion from a neutral aqueous solution into dichloromethane is obtained using a lipophilic cage-like dicopper(II) complex as the extractant. The quantitative extraction exploits the high affinity of the succinate anion for the cavity of the azacryptate. The anion is effectively transferred from the aqueous phase, buffered at pH 7 with HEPES, into dichloromethane. A 1:1 extractant:anion adduct is obtained. Extraction can be easily monitored by following changes in the UV-visible spectrum of the dicopper complex in dichloromethane, and by measuring the residual concentration of succinate in the aqueous phase by HPLC−UV. Considering i) the relevance of polycarboxylates in biochemistry, as e.g. normal intermediates of the TCA cycle, ii) the relevance of dicarboxylates in the environmental field, as e.g. waste products of industrial processes, and iii) the recently discovered role of succinate and other dicarboxylates in pathophysiological processes including cancer, our results open new perspectives for research in all contexts where selective recognition, trapping and extraction of polycarboxylates is required. </p> </div>

Formation and Trapping of the Thermodynamically Unfavoured Inverted-Hemicucurbit[6]uril

2019 ◽  
Author(s):  
Elena Prigorchenko ◽  
Sandra Kaabel ◽  
Triin Narva ◽  
Anastassia Baškir ◽  
Maria Fomitšenko ◽  
...  
Keyword(s):  
Complex Formation ◽  
Combinatorial Chemistry ◽  
Trifluoroacetic Acid ◽  
Chloride Anion ◽  
Binding Affinities ◽  
Dynamic Covalent Chemistry ◽  
Reaction Selectivity ◽  
Low Concentration ◽  
Dynamic Combinatorial Chemistry ◽  
First Time

Amplification of a thermodynamically unfavoured macrocyclic product through the directed shift of the equilibrium between dynamic covalent chemistry library members is difficult to achieve. We show for the first time that during condensation of formaldehyde and <i>cis</i>-<i>N,N'</i>-cyclohexa-1,2-diylurea formation of <i>inverted-cis</i>-cyclohexanohemicucurbit[6]uril (<i>i-cis</i>-cycHC[6]) can be induced at the expense of thermodynamically favoured <i>cis</i>-cyclohexanohemicucurbit[6]uril (<i>cis</i>-cycHC[6]). The formation of <i>i-cis-</i>cycHC[6] is enhanced in low concentration of the templating chloride anion and suppressed in excess of this template. We found that reaction selectivity is governed by the solution-based template-aided dynamic combinatorial chemistry and continuous removal of the formed cycHC[6] macrocycles from the equilibrating solution by precipitation. Notably, the <i>i-cis</i>-cycHC[6] was isolated with 33% yield. Different binding affinities of three diastereomeric <i>i-cis</i>-, <i>cis</i>-cycHC[6] and their chiral isomer (<i>R,R</i>)-cycHC[6] for trifluoroacetic acid demonstrate the influence of macrocycle geometry on complex formation.

A method for selective separation of scandium (III) from yttrium and a number of rare-earth elements for its subsequent determination

2018 ◽  
Vol 84 (11) ◽  
pp. 23-27
Author(s):  
M. I. Degtev ◽  
A. A. Yuminova ◽  
A. S. Maksimov ◽  
A. P. Medvedev
Keyword(s):  
Rare Earth ◽  
Aqueous Phase ◽  
Selective Isolation ◽  
Optimum Ratio ◽  
Extraction Condition ◽  
Sulfosalicylic Acid ◽  
Salting Out ◽  
Subsequent Determination ◽  
Toxic Organic Solvents ◽  
Metal Ions Extraction

The possibility of using an aqueous stratified system of antipyrine — sulfosalicylic acid — water for the selective isolation of scandium macro- and microquantities for subsequent determination is studied. The proposed extraction system eliminates the usage of toxic organic solvents. The organic phase with a volume of 1.2 to 2.0 ml, resulting from delamination of the aqueous phase containing antipyrine and sulfosalicylic acid is analysed to assess the possibility of using such systems for metal ions extraction. Condition necessary for the formation of such a phase were specified: the ratio of the initial components, their concentration, presence of inorganic salting out agents. The optimum ratio of antipyrine to sulfosalicylic acid is 2:1 at concentrations of 0.6 and 0.3 mol/liter in a volume of the aqueous phase of 10 ml. The obtained phase which consists of antipyrinium sulfosalicylate, free antipyrine and water, quantitatively extracts macro- and microquantities of scandium at pH = 1.54. Macro- and microquantities of yttrium, terbium, lanthanum, ytterbium and gadolinium are not extracted under the aforementioned conditions thus providing selective isolation of scandium from the bases containing yttrium, ytterbium, terbium, lanthanum, and gadolinium.

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