Difference Between Ether and Ketone

Main Difference – Ether vs Ketone

Ethers and ketones are two different groups of organic compounds. They have different chemical and physical properties. But both these compounds are essentially composed of C, H and O atoms. For the identification of these compounds, their functional groups are used. In other words, a ketone can be distinguished from an ether by identifying their functional groups. A functional group is a group of atoms that determines the chemical properties of a molecule. We can identify the difference between ether and ketone according to their functional groups. The main difference between ether and ketone is that the functional group of ether is composed of two carbon atoms bonded to the same oxygen atom whereas the functional group of ketone is composed of an oxygen atom bonded to a carbon atom via a double bond.

Key Areas Covered

1. What is Ether
      – Definition, Properties and Common Reactions of Ethers
2. What is Ketone
      – Definition, Properties and Common Reactions of Ketones
3. What is the Difference Between Ether and Ketone
      – Comparison of Key Differences

Key Terms: Ether, Functional Group, Ketone

What is Ether

Ethers are organic compounds having the general formula R-O-R’. Here, the oxygen atom is bonded to two alkyl or aryl groups. This means the oxygen atom is essentially bonded to two carbon atoms. The presence of this C-O-C structure indicates the presence of an ether group. Therefore, it acts as the functional group of ether. This functional group determines the chemical properties and the reactions that ethers undergo.

Figure 1: Diethyl Ether

At room temperature, ethers are sweet smelling liquids. Ether molecules cannot form hydrogen bonds because there are no –OH groups since the oxygen atom is bonded to two other carbon atoms. This makes the ethers to have lower boiling points than that of corresponding alcohols and other organic compounds. Therefore, ethers are highly volatile and flammable. Ethers are also less soluble in water due to the same reason. But, the oxygen atom of ether molecule has lone electron pairs, and the hydrogen atoms of water molecules have a partial positive charge. Therefore, ethers can make hydrogen bonds with water molecules.

Although the functional group of ether is inert towards most chemical reactions, there are some common reactions that ethers can undergo. This inertness is helpful in using them as solvents. The most common type of reaction that ethers show is the cleavage reaction. Here, one C-O bond is cleaved by strong acids. Apart from that, in the presence of air and oxygen, ethers form explosive peroxides.

What is Ketone

A ketone is an organic compound having the general formula R-C (=O)-R’. Here, the oxygen atom is bonded to a carbon atom via a double bond. This carbon atom is again bonded to two other alkyl or aryl groups. This structure acts as the functional group of ketone. This carbon atom is sp² hybridized. Therefore, it has only three sigma bonds around it. The geometry around this carbon atom is planar.

Figure 2: The General Structure of Ketones

Ketones are polar molecules because the –C=O double bond is polar. The electronegativity of C atom is higher than the O atom. Then the bond electrons are highly attracted by the oxygen atom than the carbon atom. This results in a partial negative charge on the oxygen atom and a partial positive charge on the carbon atom, making the ketone molecule a polar compound. Although ketone molecules cannot form hydrogen bonds with each other, these molecules form hydrogen bonds with water molecules. Since the oxygen atom of the ketone molecule is rich with electrons and the hydrogen atoms of water molecules have partial positive charges on them, the oxygen atom can form hydrogen bonds with those hydrogen atoms. Therefore, ketones are soluble in water.

The –C=O bond is highly polar. This makes the carbon atom partially positively charged. Then, this carbon atom can be attacked by nucleophiles. The type of reaction that takes place here is called nucleophilic addition reaction. There are many other reactions that involve ketones as reactants. For example, the Grignard reaction can occur in the presence of a ketone and the Grignard reagent. This reaction converts a ketone into an alcohol.

Difference Between Ether and Ketone

Definition

Ether: Ethers are organic compounds having the general formula R-O-R’.

Ketone: Ketones are organic compounds having the general formula R-C (=O)-R’.

Functional Group

Ether: The functional group of ethers has an oxygen atom bonded to two carbon atoms.

Ketone: The functional group of ketones has an oxygen atom bonded to one carbon atom.

Bonding Between Carbon and Oxygen

Ether: Ethers have -C-O single bonds.

Ketone: Ketones have -C=O double bonds.

Hybridization of Carbon Atoms

Ether: Ethers may or may not have sp² hybridized carbon atoms.

Ketone: Ketones essentially have a sp² hybridized carbon atom per molecule.

Polarity

Ether: Ethers are less polar.

Ketone: Ketones are highly polar.

Conclusion

Organic compounds are essentially composed of carbon and hydrogen atoms along with some other elements. Ethers and ketones are also organic compounds. They are composed of C, H and O atoms. An ether can be distinguished from a ketone by identifying their functional groups. Therefore, the main difference between ether and ketone is that an ether is composed of R-O-R’ functional group whereas a ketone is a compound composed of -R-C(=O)-R’ functional group.

References:

1. Wade, Leroy G. “Ether.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 24 July 2015, Available here.
2. Libretexts. “Physical Properties of Ether.” Chemistry LibreTexts, Libretexts, 5 Dec. 2016, Available here.
3. Libretexts. “Properties of Aldehydes and Ketones.” Chemistry LibreTexts, Libretexts, 6 Aug. 2017, Available here.

Image Courtesy:

1. “Diethyl-ether-2D-flat” (Public Domain) via Commons Wikimedia
2. “Ketone-general” By Nothingserious – Own work (Public Domain) via Commons Wikimedia