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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.
The complexification of the Lie algebra () is (;), the space of all n × n complex matrices with trace zero. [15] A Cartan subalgebra then consists of the diagonal matrices with trace zero, [ 16 ] which we identify with vectors in C n {\displaystyle \mathbb {C} ^{n}} whose entries sum to zero.
E–Z configuration, or the E–Z convention, is the IUPAC preferred method of describing the absolute stereochemistry of double bonds in organic chemistry. It is an extension of cis – trans isomer notation (which only describes relative stereochemistry ) that can be used to describe double bonds having two, three or four substituents .
An example of modest stereoselectivity is the dehydrohalogenation of 2-iodobutane which yields 60% trans-2-butene and 20% cis-2-butene. [5] Since alkene geometric isomers are also classified as diastereomers, this reaction would also be called diastereoselective.
) in a state with zero orbital angular momentum = into two neutrons (). Neutrons are fermions and so obey Fermi–Dirac statistics , which implies that the final state is antisymmetric. Using the fact that the deuteron has spin one and the pion spin zero together with the antisymmetry of the final state they concluded that the two neutrons must ...
However, the prefixes can usefully describe the relative configuration of a compound that has the following properties: it has at least four C atoms, exactly two of those C atoms are stereocenters, the stereocenters are adjacent, and the two substituents on each stereocenter can clearly be labeled as "larger" (usually a heteroatom such as N, O ...
The D- and L- prefixes describe the molecule as a whole, as do the (+) and (−) prefixes for optical rotation. In contrast, the ( R )- and ( S )- prefixes from the Cahn–Ingold–Prelog priority rules characterize the absolute configuration of each specific chiral stereocenter with the molecule, rather than a property of the molecule as a whole.