Haloarenes (Chlorobenzene) Lecture Notes

Vocabulary flashcards defining key terms, chemical reactions, and physical/chemical properties of haloarenes from the lecture notes.

Haloarenes

Halogen derivatives of aromatic hydrocarbons in which a halogen atom is directly attached to an aromatic ring, represented as $Ar-X$.

Sandmeyer Reaction

A preparation method for chlorobenzene where benzene diazonium chloride is heated with $Cu_2Cl_2$ in the presence of $HCl$.

Gattermann Reaction

A reaction where benzene diazonium chloride is heated with copper powder ($Cu$) in the presence of $HCl$ to yield chlorobenzene.

Diazotization Reaction

The reaction in which aniline is treated with nitrous acid, $HNO_2$ ($NaNO_2 + \text{dil. } HCl$), at ice-cold conditions to form benzene diazonium chloride.

Resonance Effect in Haloarenes

The phenomenon in chlorobenzene where delocalization of electrons imparts a partial double bond character to the $C-Cl$ bond, making nucleophilic substitution reaction difficult.

Hybridization Effect in Haloarenes

The structural factor where the chlorine-bonded carbon atom in chlorobenzene is $sp^2$ hybridized ($33.33\%$ s character), making it more electronegative, less polar, and harder to break than the $sp^3$ hybridized carbon ($25\%$ s character) in chloroethane.

Dow's Process

A nucleophilic substitution reaction of chlorobenzene with aqueous $NaOH$ or $KOH$.

Ortho-Para Director

A directive property where an attached atom (like chlorine in chlorobenzene) increases electron density at ortho and para carbon positions via resonance, guiding incoming electrophiles to attack those positions.

Fittig Reaction

The reaction of haloarenes with sodium metal ($Na$) to join two aromatic rings together.

Wurtz-Fittig Reaction

The chemical reaction of an aryl halide and an alkyl halide with sodium metal ($Na$) to form an alkylated aromatic hydrocarbon.

Reaction with Chloral

The chemical process where chlorobenzene reacts with chloral to produce the important insecticide DDT.