Current Physical Chemistry - Volume 12, Issue 2, 2022

The quantum entanglement of molecular fragments in reactive systems is approached. The "external" (inter-fragment) and “internal” (intra-fragment) correlation energies are expressed in terms of the DFT average correlation holes resulting from the coupling constant integration of the scaled electron repulsion terms in the electronic Hamiltonian. Information networks in the local and configuration resolutions are examined, and their conditional entropy (covalency) and mutual information (iconicity) descriptors are summarized. The local channels in the single Slater determinant approximation of HF theory are explored in some detail. The multisite events in the bond system for the specified molecular state are tackled, cascade (bridge) propagations are examined, and the Fermi (exchange) correlation of HF theory is discussed. The partial density matrices of interacting fragments are introduced, and their role in shaping the ensemble averages of physical observables and effective communications within reactants is examined.

An attempt is made for the first time in our laboratory to apply the Hammett and Taft equations to the five-membered heterocyclic ring systems pyrroles, pyrazoles, imidazole, and triazoles. It is shown that the pKa values of N(1)-H acidities of 3-X-pyrroles, 3-Xpyrazole, 4-X-pyrazole, 4-X-imidazole, 3-X-1,2,4-triazole and 4-X-1,2,3-triazole correlated well with Hammett σ values.

Background: For the reliable operation of deep-water production systems transporting hydrocarbons, the critical flow assurance problems to manage are wax and hydrate formation and their deposition due to the heat transfer between the production system and surroundings. Wax and hydrate deposition can restrict the flow with significant production loss. Methods: The adequate thermal insulation of such systems can allow the retention of thermal energy in the production system to ensure that the fluid cooldown temperature remains above the wax and hydrate formation temperatures. This may provide sufficient time for taking the preventive measures during an emergency shut-in operation. The purpose of this paper is to predict the cooldown temperature of a subsea Pipe-in-Pipe flowline system transporting crude oil from the reservoir to the host facility using a recently developed transient thermal model. The model incorporates the energy redistribution inside the system through the internal temperature gradient and allows to determine the requirement of thermal insulation of the Pipe-in-Pipe system to retain sufficient heat before the fluid temperature falls below the hydrate and wax temperatures. Results: The model results are compared with an industry accepted commercial simulator results to illustrate the accuracy of the model for emergency shut-in operations. Conclusion: With limited pipeline configurations and fluid properties, the model can successfully predict the requirements of thermal insulation and cooldown temperature efficiently and economically.

Aims: This study aimed to explore the ultrasonic velocity and thermoacoustic parameters for copper(I) nitrates in dimethylsulfoxide with pyridine as a co-solvent at 298 K. Background: Ultrasonic velocity variation and related factors provide a plethora of information regarding the acoustic behaviour of solutions. These studies help in understanding various kinds of interactions like ionic interactions in electrolytic solutions, molecular interactions in liquidliquid mixtures, and solute-solvent interactions. Objective: The objective of this study was to estimate the density (ρ) and ultrasonic velocity (u) of copper (I) nitrate complexes in the concentration range of 0.02-0.28 m.Kg^-1 in dimethylsulfoxide (DMSO), pyridine (Py), and binary mixtures of DMSO+Py having 0, 20, 40, 60, 80, and 100-mole percentage of Py at 298 K and 1 atmospheric pressure. The study also aimed to determine the isentropic compressibility (Κs) and apparent molal isentropic compressibility (Κs,ø ) (which is the degree of electrostatic force occurring in solution) of various salts in the binary solvent mixtures using density values and ultrasonic velocities. Methods: Using long borosilicate glass tubes, the DSA 5000 M from Anton Parr was utilized to measure the density and ultrasonic velocity at 298 K operating at a frequency of 2 MHz. Results: The apparent molal isentropic compressibility (Κs,ø) of the electrolytes was divided into the contributions of individual ions (Κ^os,ø)±. As the composition of the co-solvent increases, the (Κ^os,ø)± values for Cu (I) ions fall, i.e., they become more negative in magnitude. The (Κ^os,ø)± values for Bu4N+, Ph4B-, ClO4 -, and NO3 - are positive but decrease as they move to Py-rich regions. Strong structural effects due to interactions between solute-solute and solvent-solvent are indicated by negative (Κ^os,ø)± values. Thus, solvation increases in Py-rich regions. Furthermore, thermoacoustic parameters were evaluated from the experimentally measured values. The results were associated in terms of molecular interaction between the solute and the solvent, demonstrating that solutes have the potential to break or make structures with solvents. Conclusion: Experimental measurements of density (ρ), and ultrasonic velocities (u) in DMSO+Py at 298 K revealed that Κ^os#149; value for the copper(I) nitrates like [Cu(AN)4]+, [Cu(Phen)2]+ , [Cu(BN)4]+ [Cu(DMPhen)2]+ , [Cu(Bipy)2]+ , [Cu(TU)4]+, and the reference electrolyte decreases (less positive) or becomes more negative as the mole percentage of co-solvent increases. The Κ^os#149; values were further split to find the value of individual ions. The (Κ^os,ø)± values for Bu4N+, Ph4B-, ClO4 -, and NO3 - are positive but also show a decreasing trend in Py-rich regions. A negative (Κ^os,ø)± value indicates the presence of strong structural effects in the solvent mixture on the addition of electrolytes. Results show that solvation increases in Py-rich regions. Further correlating acoustic parameters in terms of molecular interactions also favored trends in the solvation behaviour of electrolytes. The increase in the value of Z depicts the formation of the H bond, which results in strong solute-solute interactions. The values of Κs and Lf decreased as concentration increased for all the electrolytes, indicating a significant structure-forming tendency of copper(I) electrolytes in Py-rich locations. The value of RA also increases as the composition of the co-solvent increases, indicating stronger solvation behaviour in Py rich region. Lf and Τ decreased as concentration increased for all the electrolytes, indicating strong interactions between the molecules of electrolytes with the solvent in Py-rich regions.

Objective: In this study, a synthetic thickener was synthesized by polymerizing acrylic acid, acrylonitrile, and acrylamide. Methods: The characterisation of the thickener was confirmed with Fourier transform infrared spectral data, rheology, and viscosity. The formulated thickener was utilised to prepare reactive printing paste in different concentrations, printed on cotton. The same procedure was undertaken for the study with guar gum and sodium alginate. Results: The characteristics of prints such as K/S value, strength, fastness to washing, dry/wet rubbing, and light were assessed. Conclusion: The highest K/S value and excellent fastness properties were found in the samples printed using formulated polymer.

Background: In recent years, the ultimate goal has been to learn how to select ionic liquids specifically for materialistic or molecular level applications of these neoteric materials. Progress has been initiated, but much more is needed to optimize the full potential of ionic liquids in every aspect of modern-day science. Methods: A number of engineering parameters need to be determined for the challenging flourishing of ionic liquids in sustainable commercial applications. Results & Discussion: In particular, the general absence of specific heat capacity (Cp) data is a substantial obstacle to the design of chemical reactors and heat transfer systems if any ionic liquid-based processes are to be developed beyond the laboratory scale. The specific heat capacities of ionic liquids and their mixtures have significant importance in chemical engineering work, accompanying the design and operation of reactors and heat-related operations required for the commercialization of ionic liquids and technologies associated with them. Conclusion: In this work, thermal profiles of the surfactant or sponge ionic liquids have been explored very aptly to measure the specific heat capacity (Cp) of the pyridinium cation- based surfactant or sponge ionic liquids.