Nucleofuge/nucleophile

In this reaction I" is the nucleophile, and Br" is called the leaving group (or nucleofuge). Beyond this, the classification symbolism may include a designation of the molecularity of the reaction. Molecularity is the number of reactant molecules included in the transition state. The above reaction is an 8 2 reaction, because both reactants are present in the transition state. On the other hand, this substitution... 

In nucleophilic substitution the attacking reagent (the nucleophile) brings an electron pair to the substrate, using this pair to form the new bond, and the leaving group (the nucleofuge) comes away with an electron pair ... 

When a molecule has in an allylic position a nucleofuge capable of giving the SnI reaction, it is possible for the nucleophile to attack at the y position instead of the a position. This is called the SnI mechanism and has been demonstrated on 2-buten-l-ol and 3-buten-2-ol, both of which gave 100% allylic rearrangement when treated... 

Ideally, Y should measure only the ionizing power of the solvent, and should not reflect any backside attack by a solvent molecule in helping the nucleofuge to leave (nucleophilic assistance k, p. 411). Actually, there is evidence that many solvents... 

Two new reactivity indices related to electrophilicity and nucleophilicity, electro-fugality and nucleofugality, have recently been introduced by Ayers et al. [59-61]. Electrofugality AEe is defined as... 

The proportion of C-alkylation increases in the order OTs < Br < I, a sequence which is often associated with the balance of hardness between nucleophile and nucleofuge (Smith and Hanson, 1971). The work of Kurts et al. (1974) indicates that the overall reaction rate of the crown ether-assisted alkylation increases in the order Na+ < K+ < Rb+ < Cs+, which, according to these authors, reflects the increasing distance between cation and anion in the ion pairs. The high reactivity of the tetraphenylarsenate also fits in with this picture. The decrease of the kc/k0 ratio is only small in good cation-solvating solvents such as dimethyl sulfoxide (DMSO). Alkylation of the sodium derivative of [103] with ethyl iodide in DMSO gave kc/kQ = 15.7 addition of... 

G. Aromatic Nucleophilic Substitution with Amines in which the Nucleofuge is a Sulphur Derivative... 

In fact, this heuristic principle (HP-8), which refers to nucleophilic heteroatoms directly attached to sp carbon atoms, may be also applied to nucleophilic heteroatoms directly attached to sp olefinic carbon atoms. In such cases, however, rather than a "disconnection" we would have an "unri-elimination" which will afford the substituted heteroatom as the "nucleofuge" and a triple bond as the "electrofuge". 

Whereas the terms nucleophile and electrofile refer to bond-formation reactions, the terms "nucleofuge" and "electrofuge" refer to bond-cleavage processes (see footnote 3 of ref 2b). 

Hammett s p = 1.07 in MeCN. The Ad -E route is the dominant reaction pathway, as revealed by the effects of the changes in the substituent, solvent, nucleophile and nucleofuge no competitive 5n1 reaction was observed. ... 

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