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Green Organic Reactions “on Water”
Published in Vera M. Kolb, Green Organic Chemistry and Its Interdisciplinary Applications, 2017
The Diels–Alder reaction is one of the more important carbon–carbon bond-forming reaction classes. This reaction occurs between a diene and a dienophile. These two starting materials add to each other to give a single product, which is referred to as a Diels–Alder adduct. We have shown an example of a Diels–Alder reaction in Figure 2.7, in conjunction with calculation of atom economy. For this reaction, the atom economy is 100%. From Figure 2.7, which shows the reaction between cyclopentadiene (the “diene” component) and maleic anhydride (the “dienophile” component), we see another key feature of this reaction. It is the capability to form a six-membered ring, a cyclohexene. The double bond in the latter can be used as a “handle” for additional reactions, if desired. Diels–Alder reaction is stereospecific, because it gives a preferred isomer, the so-called endo isomer. This stereospecificity is the result of the required electronic orbital overlap between the reactant molecules. This is shown in Figure 4.1, for the same reaction example as depicted in Figure 2.7.
Investigation of f-Element Interactions with Functionalized Diamides of Phenanthroline-Based Ligands
Published in Solvent Extraction and Ion Exchange, 2023
Emma M. Archer, Shane S. Galley, Jessica A. Jackson, Jenifer C. Shafer
These considerations of optimizing the bonding interactions based on the HSAB model have led to investigations regarding the nature of M-L bonding – the degree of ionicity and covalency.[5] Similar to the rest of the periodic table, bonding interactions with the f-elements are a blend of both ionic and covalent interactions and are commonly discussed as varying degrees of ionicity or covalency.[5,28] The covalent interactions observed are described using two different approaches – spatially driven orbital overlap and energetically driven overlap of atomic and molecular orbitals. Spatially driven orbital overlap covalent interactions rely on the physical overlap of the atomic and molecular orbitals to create a more covalent bond. Energetically driven orbital overlap or energy degeneracy driven covalency (EDDC) is a concept researched more recently with the An3+ which relies on the energy of the atomic or molecular orbitals to be degenerate to create a more covalent bond. It has been observed that a blend of both types of covalency dominate in creating an increase in covalency in the heavier An3+ (Am3+ and beyond).[29]
Green and cost-effective synthesis, characterization and DFT studying of silver nanoparticles for improving their biological properties by opium syrup as biomedical drug and good biocompatibility
Published in Inorganic and Nano-Metal Chemistry, 2021
Amineh Shafaei, Gholam Reza Khayati, Reyhane Hoshyar
The reaction mechanism can be explained through molecular orbital theory. The reaction takes place between two molecules if the electronic repulsion by charge attraction or orbital overlap is overcome by the amount of activation energy.[68] This energy is defined by the minimum energy difference between the HOMO energy of a molecule and the LUMO energy of the other. The orbital overlap is a necessary condition for a reaction to happen[68] and the closer the HOMO-LUMO energy of the two molecules, the faster a reaction can start. In the green synthesis of silver nanoparticles using OP, the minimum energy differences of the HOMO-LUMO of the AgNO3 and the other compounds of OP are defined and their energy levels are shown in Figure 6.