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Identification of an unknown Organic Compound

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Introduction

Identification of an unknown Organic Compound The organic compound that I have to identify can have several functional groups. These are: * Alkene * Phenol * Carboxylic acid * Aldehyde * Ketone * Primary alcohol * Tertiary alcohol * Ester The functional group in an alkene is that it has a double bond. This function allows an alkene to undergo addition reactions as it has an area of high electron density that attracts electrophiles. Therefore, in order to test for alkenes, I will use the Bromine water test as bromine can act as an electrophile. A bromine molecule may have instantaneous dipole between each other. This causes the + end of the dipoles to attack the high electron density area. If the unknown compound is an alkene, than the bromine water which is originally brown will decolourise. The mechanism for this reaction shown below; However, phenol will also decolourise bromine water as well as form white precipitant. This is an indication that the unknown compound is a phenol rather than an alkene. Phenol is an aromatic compound similar to Benzene but one of the hydrogen atoms is substituted by and OH group. ...read more.

Middle

Risk Assessments Whilst carrying out any of these tests, safety glasses, gloves and lab coats must be worn at all times. * Bromine water is classified as harmful and it should be handled very carefully. Bromine vapours are released when left in open air, this can be harmful if you inhale the vapours and asthmatics should specifically be careful. Therefore, do not leave bromine water in open air. Also do not expose bromine water to skin as it may cause burns. Any contact with skin should be washed off with plenty of water immediately. * Phenol is toxic when inhaled and highly corrosive. Therefore, it must be handled very carefully as it can cause severe burns when in contact with skin and can cause lung damage if inhaled. It must be used in a well ventilated laboratory. Any contact with skin should be washed off with plenty of water and soap. If inhaled, than seek medical help immediately. * Sodium carbonate solution is irritant to eyes although it doesn't pose a great danger. If contact is made with eyes, than wash it off with plenty of water. ...read more.

Conclusion

This observation will identify that a primary alcohol is present. 7. Test for Dehydration: Set the apparatus as shown below. Soak 2cm3 of the unknown compound with cotton wool and place it at the bottom of the test tube. Than align the test tube horizontally as shown below and place 1cm3 of aluminium oxide in the middle of the test tube. Once the apparatus is placed, heat the aluminium oxide granules with a gentle flame. This will cause vapours from the unknown compound to pass through and collect into the other test tube. As the alkene gas is collected, bung the test tube for the next part of the experiment (addition of Bromine water). Picture taken from www.chemguide.co.uk The reaction of dehydration of a tertiary alcohol is shown below. Al2O3 600K Tertiary alcohol Alkene + Water 8. Bromine water test: After the alkene gas has been collected, carefully open the bung and immediately add 5 drops of bromine water. Put the bung back in place and shake the test tube. If the unknown compound is a tertiary alcohol, than bromine water should decolourise. If it hasn't decolourised, than through the process of elimination, we can conclude that the unknown compound is an ester. ...read more.

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