Chemistry has introduced so many terms to us to an extent that we may fail to clearly draw a line between some of these words. In our case today, we are discussing the existing differences between Aldehydes and ketones. The two are organic molecules that have a carbonyl group. In this group, the carbon atom has double oxygen bond. This is an indication that ketones and aldehydes have a trigonal planar arrangement surrounding the carbonyl carbon atom.
Before we face the existing differences between these organic molecules, we have to familiarize ourselves with each of these molecules. So what is Aldehyde and how does it differ from Ketone? What is Ketone and how does it differ from Aldehyde?
Aldehyde is an organic molecule with carbonyl group which binds with another carbon from one side. On the other end, it connects with a hydrogen atom. Formaldehyde is regarded as the simplest form of aldehyde. The thing that makes formaldehyde popular is because it deviates from the general formula by containing a hydrogen atom instead of R group.
Equally, ketone is an organic molecule that has carbonyl group. This carbonyl group exists between the two carbon atoms. If closely observed, you will notice that ketone differs largely from alkane group. This is visible because of the use of suffix ‘’one’’ instead of ‘’-e’’.
With that information, we are ready to start discussing the main differences between these two organic molecules.
1. The Definition
One major difference exists in the definition of these two terms. Aldehyde is defined as an organic compound that has a general formula R-CHO. On the other hand, ketone is defined as an organic compound that has a general formula R-CO-R.
2. Functional group
The other major difference between these two organic compounds is their functional group. Aldehyde has a functional group that usually occurs at a terminus of a molecule. On the other hand, Ketone has a functional group that always occurs in the middle of a molecule.
3. The location
In the case of aldehyde, the carbonyl group binds with the hydrogen atoms from one end. In the other case, the carbonyl group binds with the carbon atoms at both sides. This is a visible difference in their chemical formulas.
Aldehydes undergo oxidation and the end product is carboxylic acids which is not the case with Ketones. Ketones never undergo oxidation without breaking carbon chain. What is formed when aldehydes are oxidized depends on the condition under which the oxidation is formed. Whether it’s done under acidic or alkaline conditions makes the biggest difference. If aldehydes are oxidized under acidic conditions, then they will form carboxylic acid. When it’s done under alkaline conditions, it won’t form the carboxylic acids.
The two organic compounds also occur at different rates. The aldehydes occur as volatile compounds while ketones occur as sugars.
The two organic compounds reacts at different rates. Ketone is the least reactive. This is an indication that Aldehydes are more reactive than Ketones. The main reason ketones are less reactive is because they exist as sugars The aldehydes exists as volatile compounds which is the reason why they are very reactive.
The two compounds have different nomenclature. As a matter of fact, the aldehydes have the suffix ‘’al’’ while the ketones have the suffix ‘’–one’’
aldehydes and ketones have a double bond between the oxygen and carbon, though, aldehydes have that double bond at the end of the molecule to an oxygen atom. Ketones on the other hand have double bonds anywhere in the molecule except at the end.
Testing the two organic compounds is very different. As a matter of fact, you can use Tollen’s reagent to know whether a solution is aldehyde or ketone. You just have to add some of this reagent to your solution and it will turn the color. If it turns to silver color, that is an aldehyde solution. The main reason for this is because aldehydes don’t oxidize.
10. Natural occurrence
The two organic compounds also differ slightly in terms of natural occurrence. Aldehydes are found in compounds such as fragrance compounds and other volatile compounds. Ketones on the other hand are found in sugars. This is the reason why they are generally known as ketoses. Though, there are aldehyde sugars that exists. These sugars are known as aldoses.