Video Transcript
Aspirin is a type of ester. Which of the following choices represents the hydrolysis products of aspirin? (A) Salicylic acid and ethanol, (B) salicylic acid and acetic acid, (C) acetic acid and methanol, (D) acetic acid and ethanol, or (E) salicylic acid and formic acid.
Let’s start by taking a look at the structure of aspirin. It contains an aryl group, known as a benzene ring; an ester group, which has a general structure of RCOOR prime; and a carboxylic acid group, with the general structure of RCOOH. While aspirin is the common name for this compound, the more formal chemical name is acetylsalicylic acid.
Now the question above is asking us what products are formed when the molecule aspirin undergoes a hydrolysis reaction. A hydrolysis reaction is a type of chemical reaction where water reacts breaking one or more bonds. Now of the three functional groups, aryl, carboxylic acid, and ester, the ester is the only functional group that will undergo a hydrolysis reaction. When an ester functional group reacts with water in a hydrolysis reaction, the carbon-oxygen single bond of the ester linkage is broken. And a new bond is formed between the oxygen of the water and the carbon of the ester linkage.
One product, an alcohol, is formed when the R prime O group of the ester linkage forms a new bond with one of the hydrogens from the water. And the other product, a carboxylic acid, is formed from the remaining OH of the water and the RC double bond O of the ester linkage.
So now let’s apply this knowledge of an ester hydrolysis to the compound aspirin. If we look at the structure of the ester, you can see that in aspirin, we have the RCOOR prime general structure of an ester, where the CH3 group is the R group and the rest of the molecule bonded to the oxygen of the ester linkage, including the benzene ring and carboxylic acid, compose the R prime group. As we’ve already discussed, when water reacts with an ester, the carbon-oxygen bond of the ester linkage breaks.
And our product formed is an alcohol made up from the R prime O group from the aspirin and one of the hydrogens from water. And this alcohol is known as salicylic acid, which is a naturally occurring molecule. And our second product is formed from the remaining OH of our water and the RC double bond O group of our ester linkage. And this carboxylic acid is the compound acetic acid.
With this information, we can revisit the question. Aspirin is a type of ester. Which of the following choices represents the hydrolysis product of aspirin? And we can see that the correct answer is answer choice (B) salicylic acid and acetic acid.
