Experiment 9 - Fischer Esterification Final Version

Experiment 9 - Fischer Esterification Final Version -...

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Experiment 9 A. Fischer Esterification Talal Zafar, 4827101- Lut Ming Cheng, 4957880, CHM2123, Section C TA: Wendy Campbell Due Date: November 24, 2008 1 – Theory and Mechanism Esters are widely synthesised in the laboratory for commercial use due to its pleasant odour. They are typically formed from the reaction of a carboxylic acid and an alcohol. In this experiment, students conducted the Fisher esterification reaction with acetic acid and n-butyl alcohol. Acetic acid is first protonated, then followed by the addition of alcohol to produce tetrahedral intermediate, proton transfer, elimination of water and finally deprotonation. C H 3 O OH + S O O OH O H Acetic acid Sulfuric acid C H 3 O + OH H S O O OH O - + CH 3 OH C H 3 OH O + OH CH 3 H C H 3 OH O O + CH 3 H H C H 3 O + O CH 3 H S O O OH O - + C H 3 O O CH 3 S O O OH O H + + O H 2 n-butyl acetate n-butyl alcohol According to the Le Hotelier’s principle, the yield of the reaction is governed by the concentration of the reactants and products. In equilibrium reaction, the principle is given rise to the equilibrium constant K. K = ([ester] × [water]) ÷ ([acid] × [alcohol]) The percent yield of equilibrium reaction is calculated under the assumption that the reaction went to completion. On the other hand, the theoretical yield is calculated based on the limiting reagent. Furthermore, there are generally no undesired reactions in esterification reaction. However, improper mixing and overheating may cause unwanted bond formation and decarboxylation. The unwanted product can be removed by washing, drying or distillation. 2 – Table of Reagents A. Fischer Esterification Compound Molar Mass (g/mol) Quantity Density (g/mL) mmol equiv. n-butyl alcohol 74.12 5.00mL 0.81 54.64 7.8 acetic acid 60.05 5.00mL 1.049 87.34 12.5 sulfuric acid 98.078 1.00mL 1.84 18.76 2.7 sodium carbonate 105.99 70.00 mL 2.5 - sodium sulfate 142.04 1.00 g 2.68 1.0 3 – Experimental procedure
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Ref: page 81 of the Organic Chemistry II lab manual Modifications Procedure B: methyl benzoate is not conducted. 4 – Observations
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Experiment 9 - Fischer Esterification Final Version -...

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