scholarly journals Evaluation of Acidity Constants and Evolution of Electronic Features of Phenol Derivatives in Different Compositions of Methanol/Water Mixture

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Mahmood Sanchooli
Keyword(s):  
Binary Mixture ◽  
Solvent Mixture ◽  
Solvent Mixtures ◽  
Water Mixture ◽  
Quantum Chemical Descriptors ◽  
Acidity Constants ◽  
Reaction Field ◽  
Phenol Derivatives ◽  
Orbital Energies ◽  
Water Solvent

This work was devoted to evaluation of acidity constants of 28 phenol derivatives in 11 different compositions of methanol/water solvent mixtures. The Onsager reaction field model was applied to any molecule of phenol derivatives dissolved in binary mixture of methanol/water, and the quantum chemical descriptors of the solute were calculated. Multiple linear regression was used to perform the reliable QSPR models in order to predict the acidity constants of the solutes. It was explored that the solvation of phenol derivatives in solvent of binary mixture of methanol/water shows a different behavior as the composition of methanol varies. Four different mechanisms proposed for solvation in 0–100 volume percent of methanol solvent. It was seen that the dipole-dipole interactions increase as the amount of methanol increases in solvent mixture, which implies the contribution of highly negative oxygens of methanol on hydrogen bondings between solute and solvent cavity. The orbital energies are a major electronic descriptor on solvation processes. This proposes that the charge exchange between frontier orbital energies of anions and the solvent molecules is the major event occurring in solution in order to stabilize the produced anions.

scholarly journals Solvent Mixture Optimization in the Extraction of Bioactive Compounds and Antioxidant Activities from Garlic (Allium sativum L.)

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 6026
Author(s):  
Vytória Piscitelli Cavalcanti ◽  
Smail Aazza ◽  
Suzan Kelly Vilela Bertolucci ◽  
João Pedro Miranda Rocha ◽  
Adriane Duarte Coelho ◽  
...  
Keyword(s):  
Binary Mixture ◽  
Bioactive Compounds ◽  
Antioxidant Activities ◽  
Pure Water ◽  
Extraction Procedure ◽  
Solvent Mixture ◽  
Total Phenolic ◽  
Solvent Mixtures ◽  
Garlic Powder ◽  
Dpph Scavenging

Garlic is a health promoter that has important bioactive compounds. The bioactive extraction is an important step in the analysis of constituents present in plant preparations. The purpose of this study is to optimize the extraction with the best proportion of solvents to obtain total phenolic compounds (TPC) and thiosulfinates (TS) from dried garlic powder, and evaluate the antioxidant activities of the optimized extracts. A statistical mixture simplex axial design was used to evaluate the effect of solvents (water, ethanol, and acetone), as well as mixtures of these solvents, after two ultrasound extraction cycles of 15 min. Results showed that solvent mixtures with a high portion of water and pure water were efficient for TPC and TS recovery through this extraction procedure. According to the regression model computed, the most significant solvent mixtures to obtain high TPC and TS recovery from dried garlic powder are, respectively, the binary mixture with 75% water and 25% acetone and pure water. These optimized extracts presented oxygen radical absorbance capacity. Pure water was better for total antioxidant capacity, and the binary mixture of water–acetone (75:25) was better for DPPH scavenging activity. These optimized extracts can be used for industrial and research applications.

scholarly journals Densities and Refractive Indices of Potassium Salt Solutions in Binary Mixture of Different Compositions

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
S. D. Deosarkar ◽  
V. V. Pandhare ◽  
P. S. Kattekar
Keyword(s):  
Binary Mixture ◽  
Potassium Salt ◽  
Solvent Mixture ◽  
Refractive Indices ◽  
Binary Solvent ◽  
Water Mixture ◽  
Salt Solutions ◽  
Potassium Salts ◽  
Binary Solvent Mixture

Densities and refractive indices of solutions of different concentrations of potassium salts, namely, KCl, KBr, and KI in 10%, 20%, 40%, and 60% (v/v) ethanol-water mixture were measured at 303.15 K. Specific refractions () and molar refractions () have been estimated from measured refractive indices and densities of solutions and interpreted in terms of interactions in salt solutions. Refractive indices increased with an increase in percentage of ethanol as well as with concentrations of potassium salts for given composition of binary solvent mixture.

scholarly journals Isolation and Purification of Fucoxanthin from Brown Seaweed Sargassum horneri Using Open ODS Column Chromatography and Ethanol Precipitation

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3777
Author(s):  
Yuemei Ye ◽  
Jingwen Sun ◽  
Liting Wang ◽  
Junwang Zhu ◽  
Wei Cui ◽  
...  
Keyword(s):  
Column Chromatography ◽  
Recovery Rate ◽  
Biological Activities ◽  
Brown Seaweed ◽  
Sargassum Horneri ◽  
Scale Production ◽  
Water Mixture ◽  
Isolation And Purification ◽  
Ethanol Precipitation ◽  
Water Solvent

As an abundant marine xanthophyll, fucoxanthin (FX) exhibits a broad range of biological activities. The preparation of high-purity FX is in great demand, however, most of the available methods require organic solvents which cannot meet the green chemistry standard. In the present study, a simple and efficient purification approach for the purification of FX from the brown seaweed Sargassum horneri was carried out. The FX-rich ethanol extract was isolated by octadecylsilyl (ODS) column chromatography using ethanol–water solvent as a gradient eluent. The overwhelming majority of FX was successfully eluted by the ethanol–water mixture (9:1, v/v), with a recovery rate of 95.36%. A parametric study was performed to optimize the aqueous ethanol precipitation process by investigating the effects on the purity and recovery of FX. Under the optimal conditions, the purity of FX was 91.07%, and the recovery rate was 74.98%. Collectively, the eco-friendly method was cost-efficient for the purification of FX. The developed method provides a potential approach for the large-scale production of fucoxanthin from the brown seaweed Sargassum horneri.

scholarly journals Effect of Sonic Agitation of a Binary Mixture of Solvents on Filling Remnants Removal as an Alternative to Apical Enlargement—A Micro-CT Study

2020 ◽  
Vol 9 (8) ◽  
pp. 2465
Author(s):  
Inês Ferreira ◽  
Pedro S. Babo ◽  
Ana Cristina Braga ◽  
Manuela E. Gomes ◽  
Irene Pina-Vaz
Keyword(s):  
Binary Mixture ◽  
Methyl Ethyl Ketone ◽  
Solvent Mixture ◽  
Methyl Ethyl ◽  
Micro Computed Tomography ◽  
Significance Level ◽  
Root Canals ◽  
Gutta Percha ◽  
Ah Plus ◽  
Mandibular Incisors

Background: This work aimed to evaluate the efficacy of sonic agitation of a binary mixture of solvents (methyl ethyl ketone/tetrachloroethylene) on filling remnants removal and compare the effects of solvent agitation with the enlargement to the next instrument size. Methods: Twenty-four mandibular incisors were prepared with ProTaper Next (X1, X2) and obturated with the single-cone technique and AH Plus sealer. The teeth were retreated with ProTaper Universal Retreatment and ProTaper Next and divided into two groups (n = 12) according to the final instrument (X3 or X4). All canals were submitted to a supplementary procedure consisting of a mixture of solvents―methyl ethyl ketone/tetrachloroethylene, agitated with EndoActivator. The volume of filling remnants was assessed through micro-computed tomography in the apical 5 mm. Statistical analysis was performed with a significance level of 5%. Results: The supplementary procedure of agitation of the solvent mixture was beneficial in both groups (p < 0.05). There were no statistically significant differences between canals re-prepared until X4 and canals re-prepared until X3 plus solvent (p > 0.05). Conclusions: An additional step with a two-solvent solution potentiated by EndoActivator showed to be very effective for the removal of gutta-percha and resinous sealer remnants from apical root canals of mandibular incisors, avoiding further enlargement.

Ionic equilibria in aqueous organic solvent mixtures The equilibria of HF in an ethanol + water mixture used for cleaning up semiconductors

1997 ◽  
Vol 433 (1-2) ◽  
pp. 77-83 ◽  
Author(s):  
Clara Ràfols ◽  
Koit Herodes ◽  
JoséLuis Beltrán ◽  
Elisabeth Bosch ◽  
Martí Rosés
Keyword(s):  
Organic Solvent ◽  
Solvent Mixtures ◽  
Water Mixture ◽  
Ionic Equilibria

Conductivity and ionic association of tetraalkylammonium halides in tert-butanol–water mixture at 25 °C

1988 ◽  
Vol 66 (5) ◽  
pp. 1223-1228 ◽  
Author(s):  
Aijaz Ahmad Ansari ◽  
M. R. Islam
Keyword(s):  
Ion Association ◽  
Ionic Association ◽  
Solvent Mixtures ◽  
Water Mixture ◽  
Solvent Interaction ◽  
Tert Butanol ◽  
Ion Association Constants ◽  
Conductance Data ◽  
Ion Size ◽  
Tetraalkylammonium Halides

The molar conductivities of Pr4NBr, Bu4NBr, Pr4NI, and BU4NI have been measured in tert-butanol–water (t-BuOH–H2O) mixtures (61.30 ≥ D ≥ 16.50) over the maximum concentration range (2 × D3 × 10−7 mol dm−3) along with the densities and viscosities of the solvent mixtures at 25 °C. The conductance data have been analysed by using the Fuoss-1978 (F78) conductance equation and the results compared with the values obtained from the Justice (J), Pitt's (P), and Fuoss–Onsager–Skinner (FOS) equations. Molar conductivities at infinite dilution (Λ0), the thermodynamic ion association constants (KA) and the distance or ion-size parameters (R0 or a0) are evaluated from these data. The F78 equation fitted the data better and yielded KA and R values which are in accord with the ion-association theories. The interpretation of these parameters is discussed to provide some insight on the magnitude of the ionic association and the ion–solvent interaction.

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