Aldehydes and Ketones

Practice flashcards covering nomenclature, bonding, physical properties, synthesis, and characteristic reactions of aldehydes and ketones based on Module 05.

Aldehydes

Molecules containing a carbonyl functional group ($C=O$) located at the end of a hydrocarbon chain, where the carbonyl carbon is attached to at least one hydrogen atom.

Ketones

Molecules containing a carbonyl functional group ($C=O$) positioned along the hydrocarbon chain, where the carbonyl carbon is attached to two carbon atoms ($R$ groups).

Carbonyl group

A functional group consisting of a carbon atom double-bonded to an oxygen atom ($C=O$), characterized by significant bond polarity with a partial positive charge ($\delta^+$) on carbon and a partial negative charge ($\delta^-$) on oxygen.

Benzaldehyde

A naturally occurring aldehyde associated with almonds.

Cinnamaldehyde

A naturally occurring aldehyde associated with cinnamon.

Carbonyl carbon hybridisation

$sp^2$ hybridisation wherein three $sp^2$ hybrid orbitals form three sigma ($\sigma$) bonds and one unhybridised $p$ orbital forms the pi ($\pi$) bond to oxygen.

Carbonyl oxygen hybridisation

$sp^2$ hybridisation wherein three $sp^2$ hybrid orbitals house one sigma ($\sigma$) bond and two non-bonding lone pairs of electrons, while one unhybridised $p$ orbital forms the pi ($\pi$) bond to carbon.

Quinones

Cyclic conjugated diketones that act as natural pigments used as dyes, such as Alizarin (1,2-dihydroxyanthraquinone).

-al

The IUPAC nomenclature suffix used for aldehydes, which are represented as "-CHO" in a molecular formula and do not require numbering.

Carbaldehyde

The suffix utilized in IUPAC nomenclature when an aldehyde functional group is directly attached to a cyclic hydrocarbon.

-one

The IUPAC nomenclature suffix used for ketones, represented as "-CO-" in a molecular formula, which requires a number to denote its position in the hydrocarbon chain.

Primary alcohol oxidation

A chemical synthesis reaction resulting in the gain of oxygen and loss of hydrogen to convert a primary alcohol into an aldehyde.

Secondary alcohol oxidation

A chemical synthesis reaction resulting in the gain of oxygen and loss of hydrogen to convert a secondary alcohol into a ketone.

Tollens' reagent

An alkaline laboratory oxidising solution containing $Ag(NH_3)_2^+$ that oxidises aldehydes into carboxylate anions while reducing silver ions to metallic silver ($Ag_{(s)}$).

Benedict's reagent

A laboratory oxidising agent composed of a copper(II) citrate solution used to test and oxidise aldehydes to carboxylic acids.

Catalytic hydrogenation

A reduction reaction using hydrogen gas ($H_2$) in the presence of a metal catalyst (such as $Pd$ or $Pt$) that converts aldehydes to primary alcohols and ketones to secondary alcohols.

Hemi-acetal

A chemical species containing a carbon atom bonded to both an $-OH$ group and an $-OR'$ group, formed by the addition reaction of an aldehyde with an alcohol.

Hemi-ketal

A chemical species containing a carbon atom bonded to two alkyl groups, an $-OH$ group, and an $-OR''$ group, produced from the addition reaction of a ketone with an alcohol.

Cyclic hemiacetal

A highly stable ring structure formed when a single molecule containing both a carbonyl and a hydroxyl group reacts with itself (e.g., in monosaccharides like glucose).

Anomeric carbon

The new stereocentre generated at the former carbonyl carbon when a sugar molecule undergoes an intramolecular ring-closure reaction to form a cyclic hemiacetal.