Benzene: Properties and Reactions

Benzen, as the simplest aromatic hydrocarbon, exhibits several important properties and undergoes characteristic reactions:

Production:

1. Trimerization of acetylene (ethyne): 3 C2H2 → C6H6
2. Reforming of petroleum distillation products

Physical properties:

• Colorless liquid
• Non-polar and insoluble in water
• Less dense than water
• Burns with a sooty flame
• More soluble in non-polar solvents

Vocabulary: Reforming - A petroleum refining process that converts naphtha into higher-octane liquid products.

Chemical properties:

1. Resistant to oxidation by KMnO4 (unlike alkenes)
2. Unreactive towards bromine water (unlike alkenes)
3. Undergoes substytucja elektrofilowa (electrophilic substitution) reactions

Example: Bromination of benzene: C6H6 + Br2 → C6H5Br + HBr

The mechanism of electrophilic substitution in benzene involves:

1. Formation of an electrophile
2. Attack of the electrophile on the benzene ring
3. Loss of a proton to restore aromaticity

Highlight: Benzene's resistance to typical alkene reactions demonstrates the stability of its aromatic structure.

Key reactions of benzene include:

1. Bromination: C6H6 + Br2 → C6H5Br + HBr
2. Sulfonation: C6H6 + H2SO4 → C6H5SO3H + H2O
3. Nitration: C6H6 + HNO3 + H2SO4 → C6H5NO2 + H2O

Definition: Electrophilic Substitution - A reaction where an electrophile replaces an atom or group in an aromatic compound.

These reactions demonstrate the unique reactivity of węglowodory aromatyczne, particularly their tendency to maintain aromaticity through substitution rather than addition reactions.