Ester Synthesis Lab Report

After the purification, the ester yield synthesised is only 67%-70% and a maximum 70% yield of ester usually is not considered to be acceptable for a synthesis reaction, instead it is considering as a poor yield of ester. The synthesised ester can only have a maximum yield of 70% because for ester in which the carboxylic acid and alcohol are sterically unhindered, a same ratio mixture of carboxylic acid and alcohol can only synthesis ester with a maximum yield of 70% ester as the reaction with the same ration of mixture will reach a state of equilibrium, which the concentration of all the species will remain constant, thus cannot goes to the completion and 100% yield of ester can’t be obtained.
Besides, during reflux, the reactant and production will evaporate and condensed back to liquid and run down back to the reactant flask. During this process, some volatile organic reactant such as alcohol and carboxylic acid or the products like ester might evaporate or escape into the atmosphere result in the low yield of ester.
In addition, during transfer of liquid, for example, transferring the liquid from a round-bottom flask to a separating funnel or transferring the organic layer from separating funnel back to
Based on Le Chatelier's principle, increase the concentration of either carboxylic acid or alcohol can increase the yield of ester. Doubling either carboxylic acid or alcohol, the theoretical yield will increase to 85%, while when either one of the carboxylic acid or alcohol is tripled, the theoretical yield goes through 90%. Therefore, a ratio of 1:3 of alcohol: carboxylic acid should be used in ester synthesis. The reason why using a ratio of 1:3 of alcohol: carboxylic acid instead of using a ratio of 3:1 of alcohol: carboxylic acid because it is easier to remove excess carboxylic acid than excess alcohol as excess carboxylic acid will react with sodium carbonate during isolation