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The reaction most often occurs at an aliphatic sp 3 carbon center with an electronegative, stable leaving group attached to it, which is frequently a halogen (often denoted X). The formation of the C–Nu bond, due to attack by the nucleophile (denoted Nu), occurs together with the breakage of the C–X bond.
Two enantiomers of a generic amino acid at the stereocenter. In stereochemistry, a stereocenter of a molecule is an atom (center), axis or plane that is the focus of stereoisomerism; that is, when having at least three different groups bound to the stereocenter, interchanging any two different groups creates a new stereoisomer.
In chemistry, stereoselectivity [1] is the property of a chemical reaction in which a single reactant forms an unequal mixture of stereoisomers during a non-stereospecific creation of a new stereocenter or during a non-stereospecific transformation of a pre-existing one. [2]
In the achiral molecules, X and Y (with no subscript) represent achiral groups, whereas X R and X S or Y R and Y S represent enantiomers. Note that there is no meaning to the orientation of an S 2 axis, which is just an inversion. Any orientation will do, so long as it passes through the center of inversion.
Diastereomers differ from enantiomers in that the latter are pairs of stereoisomers that differ in all stereocenters and are therefore mirror images of one another. [3] Enantiomers of a compound with more than one stereocenter are also diastereomers of the other stereoisomers of that compound that are not their mirror image (that is, excluding ...
Two points z, z ∗ are conjugate with respect to a line, if they are symmetric with respect to the line. Two points are conjugate with respect to a circle if they are exchanged by the inversion with respect to this circle. The point z ∗ is conjugate to z when L is the line determined by the vector based upon e iθ, at the point z 0.
Aromatic rings are usually nucleophilic, but some aromatic compounds do undergo nucleophilic substitution. Just as normally nucleophilic alkenes can be made to undergo conjugate substitution if they carry electron-withdrawing substituents, so normally nucleophilic aromatic rings also become electrophilic if they have the right substituents.
In other words, (almost) every point in the Riemann sphere has both a value and a value, and the two values are related by = /. The point where ξ = 0 {\displaystyle \xi =0} should then have ζ {\displaystyle \zeta } -value " 1 / 0 {\displaystyle 1/0} "; in this sense, the origin of the ξ {\displaystyle \xi } -chart plays the role of ∞ ...