Carbonyl vs Ketone
Carbonyl group is a common functional group in organic chemistry with a wide range of reactivity. The two types of carbonyls we are familiar with are ketone and aldehydes.
Carbonyl group is a functional group with double bonded oxygen to a carbon. Aldehydes and ketones are known as organic molecules with a carbonyl group. The carbonyl group in an aldehyde always gets number one in the nomenclature, as it is located at an end of the carbon chain. The carbonyl group of a ketone is always located in the middle. According to the type of the carbonyl compound, nomenclature differs. “al” is the suffix used to name aldehydes whereas “one” is the suffix used to name ketones. The carbon or carbons next to the carbonyl carbon is the α carbon(s), which have important reactivity due to the adjacent carbonyl. The carbonyl carbon atom is sp2 hybridized. Therefore, aldehydes and ketones have a trigonal planar arrangement around the carbonyl carbon atom. The carbonyl group is a polar group (electro negativity of oxygen is larger than carbon; therefore, carbonyl group has a large dipole moment); thus, aldehydes and ketones have higher boiling points compared to the hydrocarbons having the same weight. However, these cannot make stronger hydrogen bonds like alcohols resulting lower boiling points than the corresponding alcohols. Because of the hydrogen bond formation ability, low molecular weight aldehydes and ketones are soluble in water. However, when the molecular weight increases, they become hydrophobic. The carbonyl carbon atom is partially positive charged, hence can act as an electrophile. Therefore, these molecules are easily subjected to nucleophilic substitution reactions. The hydrogens attached to the carbon; next to the carbonyl group has acidic nature, which accounts for various reactions of aldehydes and ketones. Compounds containing carbonyl groups are widely occurring in nature. Cinnamaldehyde (in cinnamon bark), vanillin (in vanilla bean), camphor (camphor tree), and cortisone (adrenal hormone) are some of the natural compounds with a carbonyl group.
In ketones, carbonyl group is situated between two carbon atoms. General formula of a ketone is a follows.
“One” is the suffix used in ketone nomenclature. Instead of –e of the corresponding alkane “one” is used. The aliphatic chain is numbered in a way that gives the carbonyl carbon the lowest possible number. For example, CH3COCH2CH2CH3 is named as 2-pentanone. Ketones can be synthesized from the oxidation of secondary alcohols, by ozonolysis of alkenes, etc. Ketones have the ability to undergo keto-enol tautomerism. This process happens, when a strong base takes up the α-hydrogen (hydrogen attached to the carbon, which is next to the carbonyl group). The ability to release the α-hydrogen makes ketones more acidic than corresponding alkanes.
What is the difference between Carbonyl and Ketone?
• Ketones are an example for organic molecules with a carbonyl functional group.
• The carbonyl group in a ketone is always situated in the middle of a chain where as carbonyl group in an aldehyde can be located in the ends of a molecule.
• Ketones are named with the suffix “one”, which helps to recognize a ketone separately from the other carbonyl compounds.