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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 nucleophile may be electrically neutral or negatively charged, whereas the substrate is typically neutral or positively charged. An example of nucleophilic substitution is the hydrolysis of an alkyl bromide, R-Br under basic conditions, where the attacking nucleophile is hydroxyl (OH −) and the leaving group is bromide (Br −).
In the context of a specific chemical reaction between NH 3 and Me 3 B, a lone pair from NH 3 will form a dative bond with the empty orbital of Me 3 B to form an adduct NH 3 •BMe 3. The terminology refers to the contributions of Gilbert N. Lewis. [2] The terms nucleophile and electrophile are sometimes interchangeable with Lewis base and ...
Addition of a nucleophile to carbon–heteroatom double or triple bonds such as >C=O or -C≡N show great variety. These types of bonds are polar (have a large difference in electronegativity between the two atoms); consequently, their carbon atoms carries a partial positive charge. This makes the molecule an electrophile, and the carbon atom ...
In such reactions, the nucleophile is usually electrically neutral or negatively charged, whereas the substrate is typically neutral or positively charged. An example of nucleophilic substitution is the hydrolysis of an alkyl bromide, R−Br, under basic conditions, where the attacking nucleophile is the base OH − and the leaving group is Br −:
For example, OH − is a better nucleophile than water, and I − is a better nucleophile than Br − (in polar protic solvents). In a polar aprotic solvent, nucleophilicity increases up a column of the periodic table as there is no hydrogen bonding between the solvent and nucleophile; in this case nucleophilicity mirrors basicity.
This reaction is similar to nucleophilic aliphatic substitution where the reactant is a nucleophile rather than an electrophile. The four possible electrophilic aliphatic substitution reaction mechanisms are S E 1, S E 2(front), S E 2(back) and S E i (Substitution Electrophilic), which are also similar to the nucleophile counterparts S N 1 and ...