Organic Chemistry : Aldehyde and Ketone 1

We have studied organic substances that consist of only Carbons and Hydrogens. (All we have studied is the difference when the bondings and structures are different.) From now, we are going to add a new one; Oxygen.

In this, we will consider Oxygen that has a double bond to Carbon only (called Carbonyl group), which can be classified as Ketone or Aldehyde , depending on the Carbon Oxygen is bonding to as below:

Note that "R" stands for any alkyl.

IUPAC Names 

Aldehydes
- Find the longest carbon chain containing the aldehyde group. Carbon with aldehyde group is always numbered as first one.
- Then, the name is formed by changing the -e of the alkane one to -al. 
- Examples : HCHO = methanal, CH₃CH₂CH₂CHO = butanal.

Ketones
- Find the longest carbon chain containing the kerone group.
- Then, the name is formed by changing the -e of the alkane one to -one. 
- The position of the carbonyl group is denoted by a number.
- Example :  CH₃-CO-CH₃ = 2-propanone.

 Physical Properties
The carbonyl group is polar as the EN of the oxygen is greater than carbon. So, oxygen has negeative polar while carbon has positive so that Aldehydes and Ketones can do hydrogen bonding with water. They are more soluble in water if they are not too big - more than 4 carbons. However, polar in Aldehydes and Ketones gives them somewhat higher boiling and melting points. (But still lower than some like alcohol or carboxylic acid.)

 Reference : BCC M.5 Chemistry Book.

http://en.wikipedia.org/wiki/Aldehyde

http://en.wikipedia.org/wiki/Ketone 
http://www.chm.bris.ac.uk 
http://www.elmhurst.edu