Search results
Results from the WOW.Com Content Network
When the solvent is also a nucleophile such as dioxane two successive S N 2 reactions take place and the stereochemistry is again retention. With standard S N 1 reaction conditions the reaction outcome is retention via a competing S N i mechanism and not racemization and with pyridine added the result is again inversion .
Phosphorus tribromide, like PCl 3 and PF 3, has both properties of a Lewis base and a Lewis acid. For example, with a Lewis acid such as boron tribromide it forms stable 1 :1 adducts such as Br 3 B · PBr 3. At the same time PBr 3 can react as an electrophile or Lewis acid in many of its reactions, for example with amines.
If a reaction gave the enantiomer of a known configuration, as indicated by the opposite sign of optical rotation, it would indicate that the absolute configuration is inverted. In 1951, Johannes Martin Bijvoet for the first time used in X-ray crystallography the effect of anomalous dispersion , which is now referred to as resonant scattering ...
In stereochemistry, torquoselectivity is a special kind of stereoselectivity observed in electrocyclic reactions, defined as "the preference for inward or outward rotation of substituents in conrotatory or disrotatory electrocyclic reactions."
Stereochemistry, a subdiscipline of chemistry, studies the spatial arrangement of atoms that form the structure of molecules and their manipulation. [1] The study of stereochemistry focuses on the relationships between stereoisomers, which are defined as having the same molecular formula and sequence of bonded atoms (constitution) but differing in the geometric positioning of the atoms in space.
Chiral inversion is the process of conversion of one enantiomer of a chiral molecule to its mirror-image version with no other change in the molecule. [1] [2] [3] [4]Chiral inversion happens depending on various factors (viz. biological-, solvent-, light-, temperature- induced, etc.) and the energy barrier energy barrier associated with the stereogenic element present in the chiral molecule. 2 ...
As stated above, a chair flip is a ring inversion specifically of cyclohexane (and its derivatives) from one chair conformer to another, often to reduce steric strain.The term, "flip" is misleading, because the direction of each carbon remains the same; what changes is the orientation.
In stereochemistry, a chiral auxiliary is a stereogenic group or unit that is temporarily incorporated into an organic compound in order to control the stereochemical outcome of the synthesis. [1] [2] The chirality present in the auxiliary can bias the stereoselectivity of one or more subsequent reactions. The auxiliary can then be typically ...