The synthesized product, isopentyl acetate, is made by the reaction of isopentyl alcohol and glacial acetic acid with sulfuric acid (H2SO4) as the catalyzing agent. The crude ester produced in lab was isopentyl acetate, because first, the product smelled of bananas and second, the IR spectrum for the product shows that the product is isopentyl acetate. As for the purity of the product, the distillation of the crude ester showed that its boiling point was supposed to be 130°C – 140°C and the boiling points of the impurities that could have been in the crude ester have lower boiling points.
Therefore, since the crude product had a boiling point of 124°C, it indicated that there were some impurities in the crude product.
When looking at the IR spectrum, it can be seen that there is no spike around 3235cm-1, which shows that there is no presence of –OH, which makes it unlikely that isopentyl alcohol is present. This could be because the reaction did not go to completion, the extraction of the organic layers was not done with precision, since the first 0.
5mL was not taken out of the crude product before getting put into the distillation, or because during the distillation, the acetic acid evaporated because of its lower volatility than isopentyl acetate. Based on the GC/MS data, there are very few impurities and the spectrum look very similar to the 1-Butanol, 3-methyl, acetate.
1. The reaction mixture is extracted with sodium bicarbonate because the sodium bicarbonate neutralizes the excess acetic acid. The equation of the reaction is: NaHCO3(aq) + CH3COOH(aq) –> H2O(l) + CO2(g) + NaC2H3O2(aq) The carbon dioxide evaporates into the air as a gas after the reaction; the sodium acetate dissolves in water because of its polar characteristics. This is significant because it makes the acetic acid easier to remove during the extraction because it will be easily removed along with the water layer.
2. Instead of using acetic acid, isopentyl alcohol, and a few drops of sulfuric acid (to drive the reaction), the reagents would be butyric acid, ethanol, and sulfuric acid. The reason is because the different between methyl butyrate (apple) and apple butyrate (pineapple) is the extra -CH2-, which is why pineapple is called an “ethyl” instead of a “methyl”. Therefore, the acid just has to also include the additional -CH2 so that when the esterification reaction happens, the -OH on both the acid and the alcohol will combine to make H2O, separation from the reaction and combining the rest of the acid and the alcohol together.