The stereoelectronic effect refers to the influence of molecular geometry on electronic interactions and reactivity, particularly in the context of chemical bonding and reaction mechanisms. It describes how the spatial arrangement of atoms and the orientation of orbitals can affect the electronic properties of a molecule and, consequently, its reactivity. In essence, the stereoelectronic effect highlights the relationship between the arrangement of bonds in three-dimensional space and the electron distribution in molecular orbitals.
Stereoisomerism is a form of isomerism in which molecules have the same molecular formula and the same connectivity of atoms but differ in the three-dimensional arrangement of their atoms in space. This spatial arrangement can significantly affect the properties and reactivity of the compounds.
Stereoselectivity refers to the preference of a chemical reaction to produce one stereoisomer over another when multiple stereoisomers are possible. Stereoisomers are molecules that have the same molecular formula and connectivity of atoms but differ in the three-dimensional arrangement of those atoms in space.
Stereospecificity refers to the property of a chemical reaction in which the formation of products occurs in such a way that the spatial arrangement of atoms is specifically determined by the arrangement of atoms in the reactants. In other words, if a reaction yields stereoisomers, the formation of each stereoisomer is tied directly to a specific stereochemical configuration of the reactants.
Steric effects refer to the influence of the spatial arrangement of atoms in a molecule on its chemical behavior and reactivity. These effects arise from the physical size and shape of molecules, particularly the presence of bulky groups that can hinder or facilitate interactions between atoms and molecules. Key points about steric effects include: 1. **Steric Hindrance**: This occurs when large groups attached to a molecule block or hinder the approach of other reactants or the alignment necessary for chemical reactions to occur.
The Sterimol parameters are a set of quantitative descriptors used to characterize the spatial arrangement of atoms in a molecule, particularly in relation to the conformation and steric interactions of drug molecules. These parameters help in understanding how the three-dimensional shape of a molecule influences its biological activity and interactions with target proteins, enzymes, or receptors. The Sterimol parameters specifically include: 1. **L (Length)**: This measures the longest dimension of the substituent.
In chemistry, particularly in the context of molecular and structural chemistry, "strain" refers to the instability or reactivity associated with the distortion of a molecule away from its most stable conformation. This concept is essential in understanding how molecular geometry impacts the physical and chemical properties of compounds.
Supramolecular chirality refers to the phenomenon of chirality that arises in supramolecular assemblies, which are larger-scale structures formed through non-covalent interactions such as hydrogen bonding, van der Waals forces, ionic interactions, and coordination bonds. Unlike molecular chirality, which is primarily a property of individual chiral molecules that lack an internal mirror symmetry, supramolecular chirality involves the collective behavior of multiple molecules arranged in a certain way.
Syn and anti addition refer to the specific orientations of the addition of reactants across a double bond in organic molecules. These terms are especially important in the context of stereochemistry, the study of the three-dimensional arrangements of atoms within molecules. 1. **Syn Addition**: - In syn addition, the two substituents are added to the same side (or face) of the double bond.
Tacticity refers to the arrangement of the polymer chains' repeating structural units in relation to one another, particularly in stereochemistry. It is a key concept in polymer science and chemistry that affects the physical properties of polymers. There are three main types of tacticity: 1. **Isotactic**: In isotactic polymers, all the substituent groups (or side chains) are on the same side of the polymer chain, leading to a regular and symmetrical structure.
The Thorpe–Ingold effect refers to the stabilization of reaction intermediates or transition states in organic chemistry due to steric hindrance. Specifically, this effect is observed when bulky groups are positioned near a reactive center in a molecule, influencing the kinetics and thermodynamics of chemical reactions.
Topoisomers are different forms of the same molecule that have the same chemical formula but differ in the arrangement of their atoms in three-dimensional space. This term is commonly used in the context of the structural variations of DNA and in relation to the topology of chemical compounds. In the case of DNA, topoisomers can arise from variations in the winding of the double helix, such as supercoiling.
Torquoselectivity refers to the preference of a chemical reaction to generate a specific stereochemical outcome based on the torque or twisting forces that drive the interaction of reactants. This concept is particularly relevant in the context of asymmetric synthesis and organocatalysis, where the spatial arrangement of atoms in a molecule plays a critical role in determining the product formed.
Van der Waals strain refers to the additional energy or distortion that occurs in a material due to the presence of Van der Waals forces when molecules are forced closer together or further apart than their preferred equilibrium distance. These forces are weak, intermolecular interactions that arise from temporary dipoles between molecules, and they play a significant role in the physical properties and stability of materials, particularly in non-covalently bonded systems like polymers, biological molecules, and layered materials.
Viedma ripening is a process used in the field of crystallization, specifically in the area of chiral compounds. It is a way to achieve enantiomerically pure crystals from a racemic mixture—that is, a mixture containing equal amounts of two enantiomers (mirror-image molecules) of a compound. The method was developed by the chemist José Viedma in 2005.