Aldehydes and Ketones

The dehydration (the withdrawal of H-atoms) of primary alcohols leads to aldehydes.

H      
 \     
  C = O
 /     
R      

H      
 \     
  C = O
 /     
H      

  H      
   \     
    C = O
   /     
H3C      

Acetaldehyde

Glyceraldehyde [optic isomers: (D- and L- form].

gallery: structure and data of a few aldehydes

The ketones stem from secondary alcohols.

R1      
  \     
   C = O
  /     
R2      

H3C      
   \     
    C = O
   /     
H3C      

    OH    
   /     
H2C      
   \     
    C = O
   /     
H2C      
   \     
    OH    

Brevitoxin is a naturally occurring molecule with carbonyl groups (aldehyde- and lactone-). It is a poison produced by algae. The two carbonyl groups are marked in the figure below by their electron clouds. The other oxygen atoms form lactone rings by ether bridges, a hydroxyl group is also present.