Lab Experiment: A Floral Fragrance, Methyl Benzoate

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TFCH2002 Organic Chemistry II Lab Report Experiment title: A Floral Fragrance, Methyl Benzoate Name: Conor Fitzpatrick Student number: C14740151 Course code: DT422/2 Report submission date: 02/03/16 Aims • To convert benzoic acid and produce methyl benzoate by Fischer esterification. • Learn reaction mechanism involved in esterification. Benzoic acid + methanol  Methyl benzoate + water Introduction The ester functional group can be synthesized a number of different ways. These esters have very pleasant aromas and contribute greatly to the flavour and smells of many fruits. Due to this, the food industry often uses single esters to obtain synthetic flavouring agents and odours. The synthesis in this experiment…show more content…
The carbonyl group of the acid is reversibly protonated (carbonyl oxygen gets protonated as is the more basic oxygen). Proton transfer increases electrophilicity of carbonyl carbon and improves its reactivity towards nucleophiles but the charge is actually delocalised. 2. The positive charged carbonyl carbon of the protonated acid is then attacked by one of the lone pairs of oxygen atoms of the alcohol. In this step the ester bond is formed. 3. This step is balanced as oxygen’s lose or gain protons. Proton transfer from the bottom oxygen atom to a second molecule of the alcohol gives an activated complex 4. The addition of a proton to one of the hydroxyl groups of the activated complex gives a new oxonium ion. 5. This is the step in which water (one of the products formed in reaction) is formed. The loss of water from this oxonium ion and the deprotonation step gives the ester. Materials As per…show more content…
Shake funnel and rinse off water layer ( This contains the sulfuric acid and majority of methanol). Again wash the ether with 25ml of water and then wash the organic layer with 25ml of 10% sodium bicarbonate to extract unreacted benzoic acid. Again shake separatory funnel with frequent venting of pressure and opening the stopcock. Allow the separation of layers and drain off bicarbonate layer into a beaker. Wash ether layer with saturated sodium chloride solution and retain ether layer. In a small 125ml Erlenmeyer flask, dry the ether solution over anhydrous calcium chloride. Add sufficient calcium chloride so that it no longer clumps to pellets added earlier on the bottom of the flask. Remove the solvent using a rotary evaporator and weigh

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