Difference Between Carbonyl and Carboxyl

Main Difference

The main difference between the carbonyl and the carboxyl is that a carbonyl is a group which consists of a carbon atom that is double-bonded to an oxygen atom whereas carboxyl is a group which consists of a hydroxyl group and a carbonyl group that is bonded to each other through the carbon atom of the carbonyl group.

Carbonyl vs. Carboxyl

A functional group is a term of organic chemistry. It is referred to as a chemical group in a molecule that is basically responsible for the characteristic chemical reactions that occur in that molecule. The carbonyl group and the carboxyl group are the two such functional groups. A carbonyl group contains a carbon atom that is double-bonded to an oxygen atom. Carboxyl groups, on the other hand, are composed of a carbon atom that is bonded to a hydroxyl group (-OH) through a single bond and with an oxygen atom through a double bond.

The simplest organic compounds having carbonyl groups are the aldehydes and the ketones, whereas, the major class of compounds that contain the carboxyl groups is the carboxylic acids. A carbonyl group is a polar group, while, carboxyl groups also show polarity, but this polarity is in its carbonyl group.

Comparison Chart

CarbonylCarboxyl
The group which consists of a carbon atom that is double-bonded to an oxygen atom is called the carbonyl group.The group which consists of a hydroxyl group and a carbonyl group that is bonded to each other through the carbon atom of the carbonyl group is called the carboxyl group.
Chemical Formula
The chemical formula for the carbonyl group is –C(=O)-The chemical formula for the carboxyl group is –COOH
Substitutes
This group can be attached to the two more atoms or the group of atoms.This group can be attached to the one more atom or the group of atoms.
Polarity
Because of the charge separation between the carbon atoms and the oxygen atom, the carbonyl group has a polarity.The carboxyl group shows a polarity because of its carbonyl group.
Proton Releasing
Protons cannot be released from the carbonyl group.The carboxyl group is capable of releasing a proton.
Dimer Formation
Dimers cannot be formed from the carbonyl groups.The carboxyl groups are involved in the formation of dimers.
Hydrogen bonding
This type of group cannot form hydrogen bonds.This type of group is involved in the formation of hydrogen bonds.
Carbonyl C Atom
The carbonyl groups contain the carbonyl carbon atom that is bonded to an oxygen atom through a double bond.The carboxyl groups contain the carbonyl carbon atom that is bonded to an oxygen atom through a double bond.
Functional Group
A carbonyl group is a functional group of organic compounds.A carboxyl group is a functional group of organic compounds.
Nature of C Atoms
The carbonyl group contains the sp2 hybridized carbonyl carbon atoms.The carboxyl group contains the sp2 hybridized carbonyl carbon atoms.
Example
Aldehydes and KetonesCarboxylic acids

What is Carbonyl?

A carbonyl is considered as a group that comprises a carbon atom that, in turn, is attached to an oxygen atom through the double-bond. Aldehydes and ketones are well-known examples of this group. Aldehydes are made up of aldehyde groups which have the chemical formula –CHO. This group comprises a carbonyl group that is bonded to a hydrogen atom. Two alkyl groups are attached to the carbonyl group in ketones. The polarity of the carbonyl group is responsible for the reactivity of aldehydes and ketones.

The higher boiling points of the carbonyl compounds are because of it. Because of the sp2 hybridized carbonyl carbon atom, the aldehydes and ketones comprise a trigonal planar arrangement around it. Cinnamaldehyde (in cinnamon bark), camphor (camphor tree), cortisone (adrenal hormone), and vanillin (in the vanilla bean) are some of the natural compounds which have a carbonyl group.

What is Carboxyl?

Carboxyl is a group that consists of a hydroxyl group and a carbonyl group that is bonded to each other through the carbon atom of the carbonyl group. The chemical formula for this type of functional group is –COOH. The carbon atom of this group can form an additional bond with the atom besides these groups. It is an acidic group. It dissociates at high pH values and acts as a weak acid. They can form strong hydrogen bonds with water and with each other due to –OH group. As a result, the molecules of this group have high boiling points. Amino acids also have a carboxyl group, or sometimes they contain more than one carboxyl group.

Key Differences

  1. The group which consists of a carbon atom that is double-bonded to an oxygen atom is called the carbonyl group, whereas, the group which consists of a hydroxyl group and a carbonyl group that is bonded to each other through the carbon atom of the carbonyl group is called the carboxyl group.
  2. The chemical formula for the carbonyl group is –C(=O)-, on the other hand, the chemical formula for the carboxyl group is –COOH.
  3. The carbonyl group is a type of functional group that can be attached to the two more atoms or the group of atoms. Conversely, the carboxyl group is a type of functional group that can be attached to the one more atom or the group of atoms.
  4. Because of the charge separation between the carbon atoms and the oxygen atom, the carbonyl group has a polarity, on the flip side, the carboxyl group is that type of functional group which shows a polarity because of its carbonyl group.
  5. Protons cannot be released from the carbonyl group; on the other side, a proton can be released from the carboxyl group.
  6. Dimers cannot be formed from the carbonyl groups; on the other hand, dimers are formed by the carboxyl groups.
  7. The carbonyl group is a type of functional group that cannot form the hydrogen bonds, whereas, the carboxyl group is a type of functional group that can form the hydrogen bonds.
  8. The simplest examples of carbonyl compounds are the aldehydes and ketones; on the flip side, the major compounds which contain the carboxylic groups are the carboxylic acids.

Conclusion

The above discussion summarizes that carbonyl and carboxyl are the two organic functional groups which are responsible for the characteristic properties of the organic compounds. The former is a group that consists of a carbon atom that is double-bonded to an oxygen atom, whereas, the latter is a group that consists of a hydroxyl group and a carbonyl group that is bonded to each other through the carbon atom of the carbonyl group.

Harlon Moss

Harlon currently works as a quality moderator and content writer for Difference Wiki. He graduated from the University of California in 2010 with a degree in Computer Science. Follow him on Twitter @HarlonMoss

View all posts by Harlon Moss