Nucleophilic substitution reactions substrate examples include

Often the substrate is an alkyl halide (R — X = ) and the leaving group is a halide anion X ). The following equations include a generic nucleophilic substitution reaction and some specific examples. 

Spin traps can act as one-electron oxidizers. This property is even more pronounced in the interactions of traps with anion-radicals. Traps can block the ion-radical pathway. In other words, they inhibit the whole reaction, including the ion-radical step. This can be explained by both the oxidation of substrate anion-radical and chain termination due to oxidation of product anion-radical. An illustrative example is the inhibition of nucleophilic substitution of 2-chloroquinoxaline by the radical trap bis(tcrt-butyl)nitrone (Carver et al. 1982). 

Some of the most successful applications of LSV and CV are concerned with the study of the kinetics and mechanisms of the reactions of electrode generated intermediates and a large share of the electrochemical literature deals with this aspect of voltammetry [8,9,13-38,72]. The majority of electrochemical reactions include radical ions as the primary intermediates, and the reaction schemes describing the conversion of a substrate A to products are typically composed of one or two one-electron transfers and one or two chemical steps. The examples include cathodic hydrogenations, (-l-2e , +2H ") (see Chapter 6) and hydrodimerizations (-l-e , -t-H ) (see Chapter 21), and anodic additions (—2e , - -2Nu ) (see Chapter 24), dehydrodimerizations (—e , —H ) (see Chapter 22), and substitutions (—2e , +Nu , —H ) (see Chapter 24), where Nu is nucleophile)... 

As in these last examples, the descriptions of diastereoselective epoxidations were accompanied already by details on their subsequent use in ring fission reactions, we shall now switch to the various options of controlled regioselective and diastereoselective epoxide transformations. The nucleophilic opening of epoxides shows a strong dependence on substrate structure, nature of the nucleophile, and the catalyst involved, similarly to nucleophilic substitutions. Lastly, one has to consider the solvent and other details of the reaction conditions including the transition state conformation. 

A variety of aryl systems have been explored as substrates in the Knorr quinoline synthesis. Most notable examples are included in the work of Knorr himself who has demonstrated the high compatibility of substituted anilines as nucleophilic participants in that reaction. In the case of heteroaromatic substrates however, the ease of cyclization is dependent on the nature and relative position of the substituents on the aromatic ring." For example, 3-aminopyridines do not participate in ring closure after forming the anilide... 

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