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A hydroxide ion acting as a nucleophile in an S N 2 reaction, converting a haloalkane into an alcohol. In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they ...
In chemistry, an electrophile is a chemical species that forms bonds with nucleophiles by accepting an electron pair. [1] Because electrophiles accept electrons, they are Lewis acids. [2] Most electrophiles are positively charged, have an atom that carries a partial positive charge, or have an atom that does not have an octet of electrons.
The distinction is not very clear-cut. For example, in the formation of an ammonium ion from ammonia and hydrogen the ammonia molecule donates a pair of electrons to the proton; [11] the identity of the electrons is lost in the ammonium ion that is formed. Nevertheless, Lewis suggested that an electron-pair donor be classified as a base and an ...
An application of HSAB theory is the so-called Kornblum's rule (after Nathan Kornblum) which states that in reactions with ambident nucleophiles (nucleophiles that can attack from two or more places), the more electronegative atom reacts when the reaction mechanism is S N 1 and the less electronegative one in a S N 2 reaction.
In the first type, a nucleophile, an atom or molecule with an excess of electrons and thus a negative charge or partial charge, replaces another atom or part of the "substrate" molecule. The electron pair from the nucleophile attacks the substrate forming a new bond, while the leaving group departs with an electron pair. The nucleophile may be ...
In chemistry, a nucleophilic substitution (S N) is a class of chemical reactions in which an electron-rich chemical species (known as a nucleophile) replaces a functional group within another electron-deficient molecule (known as the electrophile). The molecule that contains the electrophile and the leaving functional group is called the ...
The S N 2 reaction can be viewed as a HOMO–LUMO interaction between the nucleophile and substrate. The reaction occurs only when the occupied lone pair orbital of the nucleophile donates electrons to the unfilled σ* antibonding orbital between the central carbon and the leaving group.
As it does so, it replaces a weaker nucleophile, which then becomes a leaving group; the remaining positive or partially positive atom becomes an electrophile. The whole molecular entity of which the electrophile and the leaving group are part is usually called the substrate. [1] The most general form for the reaction may be given as