As the ester is start to form in the reaction but at the same time the hydrolysis start to begin. And if you just look at this part right here, this will just result in-- this part alone will just result in a ton of having these protonated ethanols flying around. The water produced in esterification is used back in the hydrolysis to hydrolyze the ester to form the carboxylic acid and alcohol. So maybe one of the other ethanol molecules, or one of the other intermediaries in this whole reaction. The acid catalysed reaction between benzoic acid and methanol may be represented as: This esterification using the benzoic acid and methanol is known as Fisher esterification. It could be picked up by another molecule of ethanol.
Finally, the methoxide acts as a nucleophile which attack the hydroxyl group bonded to carbonyl carbon and hence to form methanol. Stage 2 of Fischer Esterification 3. The hydrogen proton might have had an electron associated with it that would then go back to a sulfuric acid, but just to make things simple, I'll just say grabs a proton from something else. It might give an electron to just the nucleus. So this guy gives an electron to the proton, but the end result is the hydrogen leaves. And now we have the actual ethanol that has attached itself, so it is no longer ethanol. The reaction was performed under reflux which sped up the reaction by continuous vapor-condensation cycles of the solution mixture as the solution boiled.
He gave an electron to a hydrogen proton. The low-molecular-weight esters have very pleasant odors and indeed are the major components of the flavor and odor aspects of a number of fruits. We now have two, three, four, five, six, seven carbons. The name, banana oil, is due to banana odour released by formation of Isopentyl acetate. So this guy can grab a proton either directly from sulfuric acid or maybe from one of the protonated ethanols, either one. So let me introduce some ethanol, and I'll do this in a different color.
And at the exact same time that this happens, this oxygen is positively charged. It still has this other lone pair over here. Report on Esterification Abstract: This report presents the process of producing an ester, specifically isopentyl acetate. The most common esterification process is Fischer-Spier esterification, named after its creators. Now, this guy has a double bond again. So you call it heptanoate.
It would do a nucleophile attack on this carbonyl carbon right here. Esters are produced when a chemical process called esterification occurs. The hydrolysis process would be the following equation: The hydrolysis process must under acidic or basic condition in order to break down the stable ester molecule. You have what was that ethanol group has now attached itself. They will be used to facilitate the reaction we're going to explore, and then they will be let go. Stage 3: The intermediate is stabilized by the elimination of water.
The adding of methanol is to ensure all the carboxylic acid could be reacted completely during reflux. He's got two lone pairs. Now, the whole reason I did this is I wanted to give you a tangible sense of what sulfuric acid looks like and why it's acidic. And then this guy can take the electron back. This produced the desired ester and water. So, the reaction involves the removal of water once the ester is formed. The mechanism of hydrolysis is shown in the diagram 4 below: Diagram 4 Water molecule acts as nucleophile to attack the carbonyl carbon of ester reversiblely.
These are kind of in equilibrium with each other. But it's just very good at taking that electron. You have an oxygen with an actual alkyl group attached to it. The concentrated sulphuric acid is added as a catalyzed in this experiment. That oxygen had one lone pair already.
Actually, it could still donate. Let me draw it as getting picked up by another molecule of ethanol. It had this electron that was participating in a double bond with this carbonyl carbon, but now it took the other side of that bond back. Now, the oxygen atom in the methanol becomes unstable and hence the C-H bond will tend to be broken down. That's why this guy might be attracted to this. Although the natural flavour may contain nearly a hundred different compounds, single esters approximate the natural odours and are often used in the food industry for artificial flavours and fragrances. The weight of the solution is very high due to the impurities present in the solution.
We have sulfuric acid there just giving protons away to the ethanol or to other things. It has attached itself to what was a carboxylic acid, so now it looks like this. Two or three anti-bumping granules are added to the mixture and fit in to the reflux set up. After the ester was isolated a percent yield of 55. The electron goes back to the oxygen. That hydrogen is now neutral.