Nitrobenzene with protic solvents

Aluminum chloride dissolves readily in chlorinated solvents such as chloroform, methylene chloride, and carbon tetrachloride. In polar aprotic solvents, such as acetonitrile, ethyl ether, anisole, nitromethane, and nitrobenzene, it dissolves forming a complex with the solvent. The catalytic activity of aluminum chloride is moderated by these complexes. Anhydrous aluminum chloride reacts vigorously with most protic solvents, such as water and alcohols. The ability to catalyze alkylation reactions is lost by complexing aluminum chloride with these protic solvents. However, small amounts of these "procatalysts" can promote the formation of catalyticaHy active aluminum chloride complexes. 

There will be some exceptions to these rules, but a good rule of thumb is like dissolves like . In this respect, solvents fall into three classes (a) protic solvents such as methanol and formamide which are hydrogen bond donors, (b) dipolar aprotic solvents (e.g., acetonitrile, nitrobenzene) with dielectric constants greater than 15 but which cannot form hydrogen bonds with the solute and (c) aprotic solvents in which the dielectric constant is weak and the solvent is non-polar, e.g., pentane or benzene. 

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