Carbonyl group is a functional group that has a carbon atom joined to an oxygen atom by a double bond and a carbonyl compound is a compound containing a carbonyl compound.

Chemists find it useful to divide carbonyl compounds into two major groups based on their chemical properties.

• In one group are the aldehydes and ketones, which have similar properties because their carbonyl groups are bonded to atoms that do not attract electrons strongly—carbon and hydrogen.

• In the second group are carboxylic acids, esters, and amides (the carboxyl family). The carbonyl-group carbon in these compounds is bonded to an atom (other than carbon or hydrogen) that does attract electrons strongly, typically an oxygen or nitrogen atom. This second group of carbonyl containing compound.

The simplest aldehydes and ketones are known by common names (formaldehyde, acetaldehyde, benzaldehyde, and acetone).

• Aldehydes are named systematically by replacing the final -e in an alkane name with -al and when necessary numbering the chain starting with 1 at the ¬CHO group.

• Ketones are named systematically by adding -one to the alkane name for saturated ketones and numbering starting with 1 at the end nearer the C=O group.

• In ketones, the location of the carbonyl group is indicated by placing the number of its carbon between the alkane name and -one.

Properties of Aldehydes and Ketones Aldehyde and ketone molecules are polar due to the presence of the carbonyl group.

• Since aldehydes and ketones cannot hydrogen bond with one another, they have lower boiling points than alcohols but higher boiling points than alkanes because of dipole–dipole interactions

• Common aldehydes and ketones are typically liquids.

• Simple aldehydes and ketones are water-soluble due to hydrogen bonding with water molecules, and ketones are good solvents for many polar and nonpolar solutes.

• Many aldehydes and ketones have distinctive odours.

• Simple ketones are less toxic than simple aldehydes.

Because ketones cannot be oxidized, treatment with a mild oxidizing agent is used as a test to distinguish between aldehydes and ketones.

• Tollens’ reagent, which consists of a solution containing silver ion in aqueous ammonia, is the most visually appealing oxidizing agent for aldehydes.

• Treatment of an aldehyde with this reagent, in which the Ag + ion is the oxidizing agent, rapidly yields the carboxylic acid anion and metallic silver.

• If the reaction is done in a clean glass container, metallic silver deposits on the inner walls, producing a beautiful shiny mirror.

A test with another mild oxidizing agent, known as Benedict’s reagent, also relies on reduction of a metal ion to produce visible evidence of the presence of aldehydes.

• The reagent solution contains blue copper(II) ion, which is reduced to give a precipitate of red copper(I) oxide in the reaction with an aldehyde.

Addition reaction of aldehydes and ketones is the addition of an alcohol or other compound to the carbon double bond to give a carbon–oxygen single bond.

Hemiacetal is a compound with both an alcohol-like ¬OH group and an ether like ¬OR group bonded to the carbon atom that was at one time the aldehyde carbonyl carbon.

Hemiketal is a compound with both an alcohol-like ¬OH group and an ether like ¬OR group bonded to the carbon atom that was at one time the ketone carbonyl carbon.

Acetal is a compound that has two ether-like ¬OR groups bonded to the same carbon atom of what was once an aldehyde.

Ketal is a compound that has two ether-like ¬OR groups bonded to the same carbon atom of what was once a ketone.

Hydrolysis is a reaction in which a bond or bonds are broken and the H¬ and ¬OH of water add to the atoms of the broken bond or bonds.