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51.
Chayanika Kashyap Indrani Baruah Shahnaz S. Rohman Sabnam S. Ullah Amlan J. Kalita Gargi Borgohain Ankur K. Guha 《International journal of quantum chemistry》2020,120(23):e26386
An extended computational approach has been utilized to explore the reactions of acids with carbonyl oxide, also known as Criegee intermediate (CI). The reactions were explored inside a water cluster containing 50 water molecules. All possibilities of product formation were considered. Among the considered acids, the rate of 1,4-insertion follows the order HCOO < HCl < HNO3. The most stable products of the reactions between the considered acids and CI have been identified. 相似文献
52.
Gargi Kundu Sriman De Dr. Srinu Tothadi Abhishek Das Dr. Debasis Koley Dr. Sakya S. Sen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(72):16533-16537
The synthesis of a SIPr [1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene] derived Kekulé diradicaloid with a tetrafluorophenylene spacer ( 3 ) has been described. Two synthetic routes have been reported to access 3 . The cleavage of C−F bond of C6F6 by SIPr in the presence of BF3 led to double C−F activated compound with two tetrafluoro borate counter anions ( 2 ), which upon reduction by lithium metal afforded 3 . Alternatively, 3 can be directly accessed in one step by reacting SIPr with C6F6 in presence of Mg metal. Compounds 2 and 3 were well characterized spectroscopically and by single-crystal X-ray diffraction studies. Experimental and computational studies support the cumulenic closed-shell singlet state of 3 with a singlet-triplet energy gap (ΔES–T) of 23.7 kcal mol−1. 相似文献
53.
Jennifer A. MacNeil Gargi B. Ray Poonam Sharma Derek G. Leaist 《Journal of solution chemistry》2014,43(1):93-108
Osmotic techniques for measuring thermodynamic activities, such as isopiestic equilibration, are well established for multicomponent solutions, especially mixed salt solutions. Surprisingly, these techniques have not yet been applied to mixed ionic surfactants, despite the numerous practical applications of these systems and the importance of the Gibbs free energy for micelle stability. In this study, mass-action equations are developed for the osmotic coefficients of solutions of ionic surfactant CA + ionic surfactant CB, with common counterion C. Extended Debye–Hückel equations are used for the ionic activity coefficients. The equilibrium constants for mixed micelle formation are evaluated by Gibbs–Duhem integration of critical micelle concentrations. Fitting the derived equations to the osmotic coefficients of aqueous sodium decanoate + sodium dodecylsulfate solutions measured by freezing-point osmometry is used to evaluate the activities of the total surfactant components. Very large departures from ideal solution behavior are indicated, including stoichiometric surfactant activity coefficients and micelle activity coefficients that drop below 0.05 and 10?8, respectively, relative to unity for ideal solutions. Osmometry offers many interesting and unexplored possibilities for studies of mixed surfactant thermodynamics. 相似文献
54.
Ray GB Chakraborty I Ghosh S Moulik SP Holgate C Glenn K Palepu RM 《The journal of physical chemistry. B》2007,111(33):9828-9837
Mixed surfactants play a promising role in surface chemical applications. In this study, interfacial and bulk behaviors of binary and ternary combinations of tetradecyltrimethylammonium bromide (C(14)TAB), tetradecyltriphenylphosphonium bromide (C(14)TPB), and tetradecylpyridinium bromide (C(14)PB) have been examined in detail using the methods of tensiometry, conductometry, fluorimetry, and microcalorimetry. The state of micellar aggregation, amphiphile composition in the micelle, extent of counterion binding by the micelle, and interaction among the surfactant monomers in the binary and ternary combinations have been quantitatively assessed in the light of the regular solution theories of Rubingh and that of Rubingh and Holland. The monomer packing in the micelles and their expected shapes have also been estimated from topological considerations. Conceptual rationalization of results has been presented together with associated energetics of the interfacial adsorption and self-aggregation in the bulk. 相似文献
55.
56.
The kinetics of electron-transfer reactions between permanganate ion and ethyl and aryl methyl ketones have been studied in aqueous MeCO2H acid medium in the presence of HClO4 at different temperatures. For ethyl methyl ketone and XC6H4COMe (X = p-Cl, p-Br or p-NO2) the reaction obeys the rate law –d[MnO4–]/dt = (kKe[H+][MnO4–][RCO Me])/(1 + Ke[H+][RCOMe]).But the oxidations of XC6H4COMe (X = p-Me and p-OMe)follow the rate equation –d[MnO4–]/dt = k3[H+][MnO4–][RCOMe]. The reaction involves a fast pre-equilibrium with intermediate formation of a permanganate ester before the two-electron transfer, rate-determining, step. A number of thermodynamic parameters have been evaluated. 相似文献
57.
Gargi Basu Ray Indranil Chakraborty Soumen Ghosh Satya P. Moulik 《Colloid and polymer science》2007,285(4):457-469
The micellization of mixed binary surfactant systems of sodium dodecylsulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS)
has been studied by conductometry, tensiometry, fluorimetry, and microcalorimetry at different mole fractional compositions.
The counter-ion binding of micelles, micellar aggregation number, thermodynamics of micellization, interaction of components
in the mixed micelles, and their compositions therein and amphiphile packing in micelles have been examined. The adsorption
features of the surfactants at the air/solution interface have also been estimated. Correlation of the results and explanations
of the findings have been presented. The difference in the head groups of SDS and SDBS has manifested interesting solution
and interfacial behaviors. 相似文献
58.
Kalyan Kali Sen Gupta Pratik Kumar Sen Gargi Mukhopadhyay 《Transition Metal Chemistry》1993,18(4):369-371
Summary The permanganate ion oxidation of PhCHO in HClO4 medium is first order in [MnO
inf4
sup-
], but of complex order with respect to [aldehyde] as well as [H+]. The influence of substituents on the reaction rate and mechanism has also been studied in 40% (v/v) aqueous AcOH and convincing evidence favours an ester formation mechanism. Thermodynamic values associated with 11 intermediate ester formation and the activation parameters associated with the disproportionation steps involved have been evaluated. 相似文献
59.
This article presents the optimization of gallic acid production using filamentous fungi from tannin-rich mixed substrates
taking into account the interaction effects of six variable process parameters. The methodology adopted for optimization was
the evolutionary operation (EVOP)-factorial design technique. This technique combines the factorial method for designing experiments
with the EVOP methodology for analyzing the experimental results systematically and arriving at conclusions according to its
decision-making procedure. Standard deviation and error limits based on 95% confidence were calculated according to the relationship
given in the literature. It was found that the best combinations of the process parameters at the optimum levels were 30°C,
80% relative humidity, pH 5.0, 48-h incubation period, 3 mL of induced inoculum, and 35 g of mixed substrate, resulting in
a gallic acid yield of 94.8% under modified solid-state fermentation. 相似文献
60.
The projectile fragmentation reactions using 58Ni and 64Ni beams at 140 MeV/n on targets 9Be and 181Ta are studied using the canonical thermodynamical model coupled with an evaporation code. The isoscaling property of the fragments produced is studied using both the primary and the secondary fragments and it is observed that the secondary fragments also respect isoscaling though the isoscaling parameters α and β changes. The temperature needed to reproduce experimental data with the secondary fragments is less than that needed with the primary ones. The canonical model coupled with the evaporation code successfully explains the experimental data for isoscaling for the projectile fragmentation reactions. 相似文献