Beirut Arab University

Faculty of Engineering

Petroleum Department

Non-Aromatic and Aromatic Hydrocarbons

Name:Diana Khraiwish Instructors: Miss Fatima Yahya

ID 201400128 Miss Rima Moghrabi Date of experiment:20/03/2017

1- Purpose of the experiment:

Test and distinguish between aromatic and non-aromatic hydrocarbons.

2- Procedure:

Permanganate Test (Baeyer):In a test tube add 3 drops of compound (2,4-dicyclopentadiene) with 1 mL alcohol (ethanol) and 1% KMnO4 (dropwise) with stirring.

Bromine test:In a test tube add 3 drops of compound with 1 mL CCl4 and dropwise of 2% bromine.

Flame test:Burn Toulene in a plate and observe the flame.

Freidel - Crafts test:In a test tube add 1 g AlCl3 and 0.2 g of toulene then add 10 drops of chloroform CHCl3 and notice the color.

3- Equations: Permanganate test:

Bromine test:

Flame test:

4- Observations and data: Permanganate test with 2,4-dicyclopentadiene results in loss of purple

color and formation of insoluble brown hydrated oxide of manganese due to the presence of C-C double or triple bond.

Bromine test gives a yellow orange to brown color. Flame test with Toluene gives a yellow sooty flame due to the presence of

aromatic ring. Freidel-Crafts test gives a pink color with toluene.

5- Conclusion:

- 2,4-dicyclopentadiene is an unsaturated hydrocarbon (alkene).- Toluene is an aromatic hydrocarbon.

6- Questions:i- What is the difference between cyclic hydrocarbons and aromatic hydrocarbons?

Aliphatic hydrocarbons are open chain materials which may be straight chain or branched. In cyclic materials the two ends of a carbon chain join together to form a ring. Cyclic hydrocarbons may contain double bonds. These are unsaturated cyclic hydrocarbons. A special example of unsaturated cyclic hydrocarbons contains alternating double and single bonds and meets certain conditions. For historical reasons they are called "aromatic". One

example of this type of hydrocarbon is benzene C6H6. So benzene is cyclic but it belongs to a subgroup of cyclic materials which are aromatic.

ii- When does bromine test fail in the detection of unsaturation?

An unknown sample is treated with small amount of elemental bromine in an organic solvent, such as dichloromethane or carbon tetrachloride. Presence of unsaturation and/or phenol in the sample is shown by disappearance of the deep brown coloration of bromine when it has reacted with the unknown sample. The formation of a brominated phenol in form of a white precipitate indicates that the unknown was a phenol. The more unsaturated an unknown is the more bromine it reacts with, and the less colored the solution will appear.