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Abstract : Pyrrolidinyl Group as Charge Donor for the Excited State Intramolecular Chargetransferin 3-(4-methoxyphenyl)-1-(4-(pyrrolidin-1-yl) phenyl) Prop-2-en-1-one
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Abstract: The absorption and steady state emission properties of a chemically synthesizedchalcone, 3-(4-methoxyphenyl)-1-(4-(pyrrolidin-1-yl) phenyl) prop-2-en-1-one (MPPP) containingasymmetrical donor and acceptor groups has been investigated both experimentally andtheoretically. The ground state, MPPP has a significant intramolecular charge transfer (ICT) character and a great sensitivity to the hydrogen bond donating ability of the medium as reflected from the absorption spectra in pure non polar, polar and neutral solvents. On the other hand, its excited singlet state exhibits high ICT characters as manifested by the drastic solvatochromic effects. These results are consistent with the data. The absorption spectra of the compound MPPP undergoes minor changes with increasing polarity of the solvents and the fluorescence spectra experiences a distinct bathochromic shifts in the both position and fluorescence quantum yields, increases reaching a maximum before decrease with increasing the solvent effects. The quantum yields decrease with increase in the solvent polarity. The magnitude of change in the dipole moment was also calculated using Austin Model 1 (AM1). These results suggest that the evidence about the intramolecular charge transfer in the emitting singlet state of this compound. The solvent dependence of quantum yields of MPPP was interpreted on the basis of positive and negative solvatokinetic as well as hydrogen bonding effects. Intramolecular charge (ICT) transfer took place from pyrrolidine nitrogen to α, β unsaturated carbonyl in the ground state.. Keywords: Chalcone, Solvatokinetic, Intramolecular charge transfer, Dipole moment, AM1 method.Download Full Article |
Abstract : Comparison of Dissolution Profiles of Furosemide Tablets Available in the Argentinian Market
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Abstract: In this work dissolution profiles of furosemide tablets of nine commercial products marketed in Argentine were evaluated. All brands fulfill the specifications of dissolution test of USP. Comparison of dissolution profiles were carried out by model-dependent and model independent approaches. Results obtained via model-dependent approach show a first order drug release mechanism especially for Brand I (reference) and Brand IV. Results obtained via model-independent approach show that there was not significant difference in Dissolution efficiency between the reference product and Brands II, III and IV and in Mean dissolution time between the reference product and Brands II, III, IV and V. Using fit factors, only Brands I and III were similar. Keywords: Furosemide, tablets, dissolution profiles, commercial products, model-dependent, model-independent.Download Full Article |
Abstract : Solubility of CO2 in Brine and Reservoir Oil for Depleted Reservoirs in China
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Abstract: Many countries play an important role to carbon capture, utilization, and Storage (CCUS) to reduce emission. Geological storage is an important approach to cope with climate change. Live oil combined with saline aquifers and gas reservoirs are among the candidates for carbon dioxide (CO2) sequestration, owing to their proven sealing capabilities and characterization. CO2 mainly from power industrial was captured to improve oil recovery in some oilfields in China, and solubility is a key factor to evaluate storage ability of reservoir and saline aquifer. In this paper, CO2 sequestration mechanisms in deplete reservoir and saline aquifer were explained. An experimental method to test solubility of CO2 in emulsion system of liver oil and brine was developed. The experimental results showed that with the salinity increased, the solubility of CO2 in reservoir oil increased slightly, and the solubility of CO2 in brine decreased. Salinity has little impact on solubility of CO2 in reservoir oil. With the pressure increased, the solubility of CO2 in reservoir oil and brine both increased. Molecular diameter of reservoir oil and white oil have inverse proportion relationship with the solubility Research on solubility of CO2 in brine and reservoir oil for depleted reservoir in China enabled us to better predict and deal with the challenges for rapid development of carbon storage. Keywords: CO2 storage, solubility, depleted reservoir, saline aquifers.Download Full Article |
Abstract : The Radical-Chain Addition to Double Molecular Bonds by the Nonbranched-Chain Mechanism: Low-Reactive Free Radicals Shortening Kinetic Chains
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Abstract: Five reaction schemes are suggested for the initiated nonbranched-chain addition of free radicals to the multiple bonds of the unsaturated compounds. The proposed schemes include the reaction competing with chain propagation reactions through a reactive free radical. The chain evolution stage in these schemes involves three or four types of free radicals. One of them is relatively low-reactive and inhibits the chain process by shortening of the kinetic chain length. Based on the suggested schemes, nine rate equations (containing one to three parameters to be determined directly) are deduced using quasi-steady-state treatment. These equations provide good fits for the nonmonotonic (peaking) dependences of the formation rates of the molecular products (1:1 adducts) on the concentration of the unsaturated component in binary systems consisting of a saturated component (hydrocarbon, alcohol, etc.) and an unsaturated component (olefin, allyl alcohol, formaldehyde, or dioxygen). The unsaturated compound in these systems is both a reactant and an autoinhibitor generating low-reactive free radicals. A similar kinetic description is applicable to the nonbranched-chain process of the free-radical hydrogen oxidation, in which the oxygen with the increase of its concentration begins to act as an oxidation autoingibitor (or an antioxidant). The energetics of the key radical-molecule reactions is considered. Keywords: Binary System, Unsaturated Compound, Low-Reactive Radical, Autoinhibitor, Competing Reaction, Non-Branched-Chain Addition, Kinetic Equation, Rate, Parameters, Thermochemical Data, Energy.Download Full Article |
