Methyl Benzoate Synthesis

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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…
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 product. Results 1 mole of benzoic acid (C6H5COOH = 122.12grams) reacts with 1 mole of methanol (CH3OH = 32grams/mole) to produce 1 mole of methyl benzoate (C6H5COOCH3 = 136.15grams) and 1 mole of water. 5.0grams of benzoic acid Molar mass of benzoic acid: 122.12g/ml 5.0g122.12g=0.041moles 19.75grams of…show more content…
The percentage recovery of methyl benzoate was 28.93% which is a very low result. This was not as expected. This could be due to a number of different factors, mainly human error. The glassware used may have been too large for the quantities handled. The mixture may have not been refluxed fully. Initially not all of the 5.0grams of benzoic acid went into the round-bottomed flask as there was still residue left on weighing boat. This would mean the starting amount of benzoic acid was less then stated. There was some product loss during the draining of the aqueous layers. All these will account for the low yield that was produced. However, the ester formed produced a wintergreen odour and this was to be suspected. Conclusion Due to the very low percentage yield, the results were not what was wanted. The ideal product range would have been between 80 – 100% which was far from the recovered product. When you mix a carboxylic acid with a alcohol in the presence of a catalyst an ester is formed that gives off a pleasant fragrance. In the reaction a wintergreen smell was composed and this is a positive result from the experiment proving the mechanism of

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