Back to: CHEMISTRY SS3
Welcome to class!
In today’s class, we will be talking about aromatic hydrocarbon. Enjoy the class!
Benzene is a typical aromatic compound with a molecular formula of C6H6. It has the structure of:
- From coal tar: The destructive distillation of coal produced coal tar which contains benzene
- From petroleum: The dehydrogenated of alkane using vanadium(v)oxide (v2O5) as a catalyst at 500oC and 20 atmos give benzene
C6H14 V2O2 → C6H6 + 4H2
The process is known as catalytic reforming.
- From polymerization of ethyne:
3 ( H – C = C – H ) → C6H6
- Describe three (3) ways of preparing benzene.
- Draw the structure of benzene.
- It has a pleasant odour.
- It has a boiling point of 80oC.
- Benzene can dissolve in water.
- It burns with a sooty flame.
Benzene can undergo both an additional reaction and substitutional reaction.
- Hydrogenation: Benzene reduces to cyclo-hexane if hydrogen gas is passed through finely divided nickel at 150oC.
- Halogenation: In the presence of ultra-violet light, benzene reacts with halogen to produce a cyclic compound.
- Substitution reaction.
- Benzene undergoes substitution reaction due to the presence of its single bonds.
- Halogenation e.g. Cl2, Br2, I2
This occurs in the mixture of HNO3 and H2SO4 together with benzene
It involves reactions of benzene with halo-alkanes in the presence of AlCl3.
- It is used as a solvent to dissolve organically.
- It is used as a fuel in petrol.
- It is used in the manufacture of aromatic compound e.g. benzoic acid.
- State two (2) uses of benzene
- Identify two (2) chemical properties of benzene with examples.
Derivatives of benzene
- Give another name to the following compounds (a) Phenol (b) Toluene
- State four (4) derivatives of benzene.
New School Chemistry By .O.Y. Ababio, pg 492-494.
- Benzene can be prepared from the following except (a) Coal tar (b) petroleum (c) Alkanol (d) Ethyne
- Benzene can undergo additional reaction due to the presence of (a) double bonds (b) single bonds ( c) hydrogen ( d) carbon.
- Benzene undergoes the following reaction except. (a) substitution (b) addiction (c) Hydrogenation ( d) polymerization
- The technique used in separating a mixture of common salt and water is (a) evaporation (b) sublimation (c) decantation (d) chromatography.
- a. State two (2) uses of Benzene
- identify two (2) physical properties of benzene.
- a. How would you prepare benzene?
- State two (2) chemical properties of benzene.
In our next class, we will be talking about Alkanols. We hope you enjoyed the class.
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