Nucleofuge
Encyclopedia
A nucleofuge is a leaving group
which retains the lone pair from its previous bond with another species. For example, in the SN2 mechanism
a nucleophile
attacks an organic compound containing the nucleofuge (the bromo group
) which simultaneously breaks the bond with the nucleofuge.
After a reaction nucleofuges may contain either a negative or a neutral charge; this is governed by the nature of the specific reaction.
The word 'nucleofuge' is commonly found in older literature, but its use is less common in current literature in which the word leaving group
dominates.
Leaving group
In chemistry, a leaving group is a molecular fragment that departs with a pair of electrons in heterolytic bond cleavage. Leaving groups can be anions or neutral molecules. Common anionic leaving groups are halides such as Cl−, Br−, and I−, and sulfonate esters, such as para-toluenesulfonate...
which retains the lone pair from its previous bond with another species. For example, in the SN2 mechanism
SN2 reaction
The SN2 reaction is a type of nucleophilic substitution, where a lone pair from a nucleophile attacks an electron deficient electrophilic center and bonds to it, expelling another group called a leaving group. Thus the incoming group replaces the leaving group in one step...
a nucleophile
Nucleophile
A nucleophile is a species that donates an electron-pair to an electrophile to form a chemical bond in a reaction. All molecules or ions with a free pair of electrons can act as nucleophiles. Because nucleophiles donate electrons, they are by definition Lewis bases.Nucleophilic describes the...
attacks an organic compound containing the nucleofuge (the bromo group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
) which simultaneously breaks the bond with the nucleofuge.
The word 'nucleofuge' is commonly found in older literature, but its use is less common in current literature in which the word leaving group
Leaving group
In chemistry, a leaving group is a molecular fragment that departs with a pair of electrons in heterolytic bond cleavage. Leaving groups can be anions or neutral molecules. Common anionic leaving groups are halides such as Cl−, Br−, and I−, and sulfonate esters, such as para-toluenesulfonate...
dominates.