Analysis of Hydrocarbons 1

BIOORGANIC
CHEMISTRY

BioOrganic Chemistry Laboratory – CH 205 (2010-2011) Experiment 3

Analysis of Hydrocarbons

Maria Patricia Dizon, Nikko Paolo Ebarvia, Darlene Louise Estrada* and Rizhelle Evan Evaristo
Department of Occupational Therapy, College of Rehabilitation Sciences
University of Santo Tomas, Espaňa Street, Manila 1008

Date Submitted: February 2, 2011 Abstract: Organic compounds hexane, heptane, cyclohexane, cyclohexene, benzene, and toluene were subjected to different physical and chemical tests todifferentiate their intrinsic physical properties and chemical properties in terms ofstructure and behaviour. Nitration test (test for the presence of aromatic ring), Bromine test (test for the presence of unsaturation), and Basic oxidation test (test for an alkyl substituted benzine) were done. We were given an unknown which we tested (Nitration,Bromine, Basic oxidation) and found out that it was an aromatic unsaturated hydro carbon.

Keywords: hydrocarbons, hexane/ cyclohexane, cyclohexene, naphthalene, toluene 1. Introduction This experiment aims to differentiate the different types of hydrocarbon as well as to identify the unknown through parallel chemical test. In this experiment we were expected to characterize hydrocarbons based on their chemical reactions. Hydrocarbons are organic compounds that consist of only C and H atoms. They include the alkanes, alkenes, alkynes, and aromatic hydrocarbons. Because of their relatively nonpolarity, all hydrocarbons are insoluble in water. Hydrocarbons may be divided into two large classes namely: Saturated hydrocarbons and unsaturated hydrocarbons. Saturated hydrocarbons are the simplest type of organic compounds. They are hydrocarbons in which all carbon-carbon bonds are single bonds. An example of a saturated hydrocarbon is an alkane. Unsaturated Hydrocarbons are hydrocarbons that contain one or more carbon-carbon multiple bonds like double bonds, triple bonds, or both. Saturated and Unsaturated hydrocarbons have similar physical properties, but their chemical properties are different. Unsaturated hydrocarbons are chemically more reactive than saturated ones. This is because of the presence of carbon-carbon multiple bonds in such compounds and these multiple bonds serve as locations were chemical reactions can occur. Hexane is an alkane hydrocarbon with a chemical formula ofC6H14, molar mass of 86.18 g/mol, and a boiling point of 69°C. Isomers of hexane are mostly non-reactive, and are frequently used as solvents in organic reactions because they are very non-polar. They are common constituents of gasoline and leather products.

Cyclohexane is a cycloalkane with the molecular formula C6H12, molar mass of 84.160 g/mol, and boiling point of80.74°C. It is used as a non-polar solvent and a raw material for the production of adipic acid and caprolactam. Cyclohexane is produced on an industrial scale by reacting benzene with hydrogen

Cyclohexene is a cycloalkane with a chemical formula of C6H10, molar mass of 82.143 g/mol, and a boiling point of 82.98°C. It is not very stable upon long term storage and exposure to light and air should be distilled before use to eliminate peroxides. It has a very sharp smell resembling an oil refinery.

Naphthalene, also known as naphthalin, bicyclo[4.4.0]deca-1,3,5,7,9 pentene or antimite is a crystalline, aromatic, white, solid hydrocarbon with formula C10H8 and the structure of two fused benzene rings. It is best known as the traditional, primary ingredient of mothballs. It is volatile, forming a flammable vapor, and readily sublimes at room temperature, producing a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass.

Toluene is an aromatic hydrocarbon with a molecular formula ofC7H8, molar mass of 92.14 g/mol, and a boiling point of 110.6°C. Toluene reacts as a normal aromatic hydrocarbon towards electrophilic aromatic substitution. It is a water-insoluble liquid with a smell of paint thinners, and it is widely used as an industrial feedstock and solvent.

2. Methodology Five test tubes for each test were used and was labeled accordingly. 5 samples were used in the experiment namely hexane/ cyclohexane, cyclohexene, naphthalene, toluene and an unknown. First the Nitration test, 5 drops of each sample was placed separately on a test tube. 8 drops of nitrating agent (H2SO4/ HNO3) was added to each compound then 20 drops of distilled water was added next. In the Bromine test, the same samples were used, 3 drops of Br2 in DCM was placed. 5 drops of the samples were then added. Lastly for the Basic Oxidation test, same samples were used again. 5 drops of the sample was placed, 3 drops of 1 % KMNO4 was added next, and finally 2 drops of 6M NaOH was added.

3.Results and Discussion

OBSERVATIONS | Sample | Nitration test | Bromine test | Basic Oxidation test | Cyclohexane | -colorless | -orange liquid | -greenish liquid | Cyclohexene | -it turned to a dark color (blackish) | -colorless | -brownish liquid | Naphthalene | -translucent liquid with yellow globules | -orange liquid | -greenish liquid | Toluene | -transparent with a yellowish liquid on top | -orange liquid | -greenish liquid | Unknown | -translucent liquid with yellow globules | -orange liquid (very light) | -greenish liquid with brown precipitate | For Nitration test, yellow globules were to be observed, two of the samples were positive, Naphthalene and the unknown; for the Bromine test, a colorless solution should be the end result, one sample, Cyclohexane, was positive; for the basic oxidation test, a positive result shows a brown precipitate in which Cyclohexene turned positive and partly as well as the unknown. The unknown solution turned positive in nitration test, having similar results with Naphthalene which was an aromatic hydrocarbon, and also partly turned positive in Basic Oxidation test as with cyclohexene which was unsaturated. Therefore, the unknown was an unsaturated aromatic hydrocarbon. 3. Conclusion

4. References

[1] http://library.thinkquest.org/3659/orgchem/hydrocarbons.html
[2] http://www.scribd.com/doc/25377353/Classification-Tests-for-Hydrocarbons
[3] http://en.wikipedia.org/wiki/Naphthalene

References: [1] http://library.thinkquest.org/3659/orgchem/hydrocarbons.html [2] http://www.scribd.com/doc/25377353/Classification-Tests-for-Hydrocarbons [3] http://en.wikipedia.org/wiki/Naphthalene