An aldehyde is a functional group characterized by an oxygen atom double bonded to a carbon atom at the end of a carbon chain, this carbon being bonded to just one other carbon atom:

(Where -R represents the carbon chain.)

Aldehyde names are formed by adding the suffix -al to the parent alkane, for example an aldehyde with 5 carbons is pentanal. Aldehydes can be produced by oxidation of primary alcohols. In the laboratory this may be achieved by heating the alcohol in an acidified solution of potassium dichromate, which is reduced to green Cr³⁺ during the reaction, or by the so called "Swern oxidation" ((CO)₂Cl₂ + (Me)₂SO).

See also: Ketone

Table of contents

1 Naming Aldehydes 2 Examples of Aldehydes 3 Reactions Involving Aldehydes 3.1 Preparing Aldehydes 3.2 Reacting Aldehydes

Naming Aldehydes

Aliphatic aldehydes are named as derivatives of their longest alkyl chain. Thus, HCHO is named as a derivative of methane, and CH3CH2CH2CHO is named as a derivative of butane. The suffix -al replaces the -e of the alkane name. Thus, HCHO is named methanal, more commonly known as formaldehyde, and CH3CH2CH2CHO is named butanal.

When a -CHO group is attached to a ring, the suffix -carbaldehyde is used. Thus, C6H5-CHO is known as benzenecarbaldehyde.

Examples of Aldehydes

• Methanal (Formaldehyde)
• Ethanal (Acetaldehyde)
• Propanal
• Butanal
• Pentanal
• Glucose

Preparing Aldehydes

• Reacting a primary alcohol with some oxidizing agents, such as pyridinium chloride, yields an aldehyde.
• Reacting an alkene with ozone will cause the bond to break if there is a vinylic hydrogen.
• Reacting an ester with DIBAH can cause reduction, yielding an aldehyde.