Nucleophilic substitution reactions general form

Commercially available alkali amides can also be used in nucleophilic substitution reactions to form anilines, although the reaction mechanisms differ greatly from those of direct nucleophilic substitution reactions conducted with weak bases. The reactions generally occur rapidly at room temperature, and even at temperatures as low as — 33 °C in the case of amination in liquid ammonia. A mixture of products often results, but the entering amine is rarely found more than one carbon atom away from the leaving halogen (equation 2). 

The alkylation process possesses the advantages that (a) a wide range of cheap haloalkanes are available, and (b) the substitution reactions generally occur smoothly at reasonable temperatures. Furthermore, the halide salts formed can easily be converted into salts with other anions. Although this section will concentrate on the reactions between simple haloalkanes and the amine, more complex side chains may be added, as discussed later in this chapter. The quaternization of amines and phosphines with haloalkanes has been loiown for many years, but the development of ionic liquids has resulted in several recent developments in the experimental techniques used for the reaction. In general, the reaction may be carried out with chloroalkanes, bromoalkanes, and iodoalkanes, with the reaction conditions required becoming steadily more gentle in the order Cl Br I, as expected for nucleophilic substitution reactions. Fluoride salts cannot be formed in this manner. 

Molecular transport junctions differ from traditional chemical kinetics in that they are fundamentally electronic rather than nuclear - in chemical kinetics one talks about nucleophilic substitution reactions, isomerization processes, catalytic insertions, crystal forming, lattice changes - nearly always these are describing nuclear motion (although the electronic behavior underlies it). In general the areas of both electron transfer and electron transport focus directly on the charge motion arising from electrons, and are therefore intrinsically quantum mechanical. 

Lifetimes of the ionic intermediates of nucleophilic substitution are generally correlated to the pathways followed under given reaction conditions. Information on the lifetimes of ionic intermediates formed by bromine addition to olefins in methanol, as determined by the azide clock method, do not allow the different reaction pathways to be distin-... 

Reactions that form carbon-carbon bonds are of great importance in organic synthesis because they enable smaller compounds to be converted to larger compounds. Forming these bonds by nucleophilic substitution reactions requires a carbon nucleophile—a carbanion (carbon anion), as shown in the following general equation ... 

Nucleophiles often participate in nucleophilic substitution reactions. The general form of these reactions may be represented by the following equation where Nuj and Nu2 are nucleophiles ... 

The quaternization of amines and phosphines with haloalkanes has been known for many years. In general, the reaction may be carried out using chloroalkanes, bromoaUcanes, and iodoalkanes, with the milder reaction conditions in the order Cl Br I, as is expected for nucleophilic substitution reactions. Fluoride salts cannot be formed in this manner. 

In general, the reactivity of the pyridine ring in nucleophilic substitution reaction decreases in the row C2 > C4 > C3. Consequently, more synthetic routes are reported for 4-fluoropyridines compared to 3-fluoropyridines. Pyridines can form cationic complexes with electrophiles resulting in activation of heterocyclic ring toward nucleophilic substitution. On the other hand, pyridines have signih-cantly reduced reactivity toward electrophiles and typically undergo electrophilic substitution reactions in the present of strong Lewis acids selectively in the position 3. ... 

The general form of a nucleophilic substitution reaction is as follows,... 

---