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The Prelude of Green Syntheses of Drugs and Natural Products
Published in Ahindra Nag, Greener Synthesis of Organic Compounds, Drugs and Natural Products, 2022
Leonardo Xochicale-Santana, C. C. Vidyasagar, Blanca M. Muñoz-Flores, Víctor M. Jiménez Pérez
When it comes to organic reactions, it is normal to believe that they take place in a solvent medium. This principle has a straightforward rationale. That is, if the reactants are in a homogeneous solution, they can interact effectively, which makes stirring, shaking, or other forms of agitation easier, allowing the reactant molecules to come together quickly and continuously. Furthermore, if uniform heating or cooling of the mixture is needed, it is relatively simple to do so in a solution. However, the position of a solvent in an organic reaction is much more complicated than simply providing a homogeneous environment for many reactant collisions to occur. A solvent can dramatically increase or decrease the speed of a reaction.82 The rate of a reaction can be influenced by changing the solvent, and it can be strong enough to alter the reaction's trajectory. This could result in different product yields and ratios. As a result of the solvation of the reactants, products, transition-state, or other intervening species, a solvent could be strongly and inextricably linked to the mechanism of an organic reaction. Electrostatic, steric, and conformational effects, among other things, are responsible for certain close interactions between the solvent and the reaction partners. Despite its heavy presence, the solvent does not usually become part of the substance (except in solvolysis reactions) and is recovered intact after the reaction is completed. Even then, conducting a reaction in the absence of a solvent should not be considered or expected.83
New Technologies Used in Wastewater Treatment
Published in Pankaj Chowdhary, Sujata Mani, New Technologies for Reclamation of Industrial Wastewater, 2021
Solvents are not an integral part of any chemical compounds undergoing reactions; formerly, they play an essential role in synthesis and production. Solvents are extensively used in the classical chemical process to dissolve reactants, separate mixtures, extract and wash products, clean reaction gadgets, and scatter products for normal applications. Though the invention of organic solvents has led to remarkable advances in chemistry, the legacy has resulted in various environmental and health concern.
Solvents
Published in Ronald M. Scott, in the WORKPLACE, 2020
When considering solvents, the importance of polarity can be summarized briefly: “Like dissolves like.” Nonpolar substances are most soluble in nonpolar solvents, and polar substances dissolve best in polar solvents. Bearing grease, which is very nonpolar, dissolves readily in such nonpolar liquids as kerosene or toluene, but not in such polar liquids as water or methanol. Lye, an ionic solid, dissolves in water or ethyl alcohol, but not in kerosene or toluene. We must select a solvent or a mixture of solvents that is suitable for the particular solute.
Machine learning models for occurrence form prediction of heavy metals in tailings
Published in International Journal of Mining, Reclamation and Environment, 2023
Jiashuai Zheng, Mengting Wu, Zaher Mundher Yaseen, Chongchong Qi
Overall, the average importance value of EC was 0.442, placing it as the most important factor influencing the percentages of the seven occurrence forms. The significant influence of EC occurs due to this parameter’s ability to affect solubility by influencing the strength of intermolecular forces between the solute and solvent molecules. Polar solvents typically have a higher propensity to dissolve polar solutes, whereas non-polar solvents tend to dissolve non-polar solutes. The solubility generally increases with the polarity and electronegativity of the solvent species [51,52]. Following EC, the atomic number, atomic mass, and sum of the total concentrations also ranked highly with average feature importance scores of 0.211, 0.142, and 0.091, respectively. Ho and Egashira et al. [53] also found a significant effect of total concentration on the occurrence form, and the similar conclusions was reached by Guan et al [54]. Unlike the other fractions, the most important feature of F5 was not EC but instead the sum of the BCR concentration, which has a feature importance value of 0.332; this was followed by the total element concentration and EC, which had values of 0.267 and 0.237, respectively.
Simulation of mass transfer during sucrose extraction from sugar beet using a combined analytical and semi-empirical model
Published in Chemical Engineering Communications, 2022
S. Z. Hosseini, Behrooz Abbasi Souraki
Figure 4(a) and (b) show the predicted (Azuara model) and experimental sucrose loss and moisture gain at 40, 50, and 60 °C, respectively. The results of the proposed model and experimental data relatively overlapped, suggesting the acceptable accuracy of the model. Changes in the slope of sucrose loss and water gain in Figure 4 indicate the very fast rate of mass transfer at the early stages of solid-liquid contact. As time passed, the sucrose and moisture transfer gradually decreased. The solubility rose with temperature enhancement, thus, the solvent dissolved more solutes (Chan et al. 2014). The intercellular voids fill by passage of time which decrements the rate of moisture gain and sucrose loss. Similar results were reported by Ali Yildirim et al. on the water diffusion into chickpeas during the soaking process (Yildirim et al. 2011).
Thermal and optical properties of amphitropic liquid crystals derived from cholesterol and cinnamic acid
Published in Liquid Crystals, 2021
Yi-Hua Hung, Chun-Yen Liu, Wei-Chieh Chen, Jui-Hsiang Liu
Since the temperature as well as the concentration of the compound influence the lyotropic liquid crystalline properties, the concentration of CCM/chloroform was fixed at 60/40 and the temperature dependence on selective light reflection was investigated between 30°C and 60°C. The results are summarised in Figure 9. After increasing the temperature from 30°C to 60°C, the reflected band exhibited a blue shift from approximately 590 nm to 500 nm. Increases in temperature usually increase the solubility of the substrate in the solvent. The results in Figure 9 indicate that heating the system may decrease the pitch of the lyotropic cholesteric liquid crystals, leading to the appearance of a blue shift. It is noteworthy that the wavelength of the reflected band falling in the visible region is reversible. Theoretically, from the results, the fabricated lyotropic liquid crystal film could be used for the sensing of temperature. Different reflection bands show different colours, and the variations due to temperature could be seen with the naked eye. Since the boiling point of chloroform is 61.2°C, the lyotropic cholesteric liquid crystal phase is present at temperatures lower than 61.2°C. When the temperature is higher than the boiling point, the selective reflection band disappears immediately. This could be due to the disappearance of the interaction balance between the CCM and chloroform molecules.