Nucleophilic Substitution and Addition Reactions

Nucleophilic substitution reactions involving free arenes are very difficult to carry out. The complexation causes a decrease of electron density on the arene molecule and therefore considerably facilitates nucleophilic attack. Thus, the chlorobenzene chromium complex [Cr(PhCl)(CO)3] easily reacts with sodium methanolate to give anisole chromium tricarbonyl [Cr(PhOMe)(CO)3]. The complex [Cr(PhF)(CO)3] reacts in a similar way. 

The substitution of the halogen (fluorine and chlorine) also occurs very easily in arene cyclopentadienyl iron complexes. 

Nucleophilic addition to the arene ligand is a specific reaction for the cationic arene complexes. It does not occur for uncoordinated arenes. Dependent on the complex and the conditions of the reaction, addition of neutral nucleophiles such as phosphines. 

For rhenium and manganese compounds, one molecule of nucleophile is added, while in the case of iron and ruthenium, two molecules are added  

The displacement and exchange of arene ligands with labeled arenas is a characteristic reaction for arene metal complexes  

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Since 05 is a conjugate base of weak acid, HO2 (p ATa=4.9), and also an anion radical at physiological pH, it can perform both ionic and radical reactions. As an anion 05 has reactivies such as nucleophilic substitution and addition reactions, and as a radical, it performs hydrogen-withdrawal reactions, one-electron reduction or oxidation reactions and the disproportionation reaction. In aqueous medium, the radical reactions are... 

Electrophilic and nucleophilic substitution and addition reactions of enamines... 

Nucleophilic substitution and addition reactions of olefins are possible with Pd2 salts. A typical example is the formation of acetaldehyde by the reaction of ethylene with water (Wacker reaction). As nucleophiles, water, alcohols, phenols, carboxylic acids, amines, enamines, carbanions derived from active methylene compounds, and carbon monoxide react with olefins with stoichiometric consumption of Pd2 salts. 

Alkyl and Alkenyl Bromides. LiBr has been extensively used as a source of bromide in nucleophilic substitution and addition reactions. Interconversion of halides and transformation of alcohols to alkyl bromides via the corresponding sulfonate or trifluoroacetate have been widely used in organic synthesis. Primary and secondary alcohols have been directly converted to alkyl bromides upon treatment with a mixture of Triphenylphosphine, Diethyl Azodicarboxylate, and LiBr. ... 

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