Final answer:
The Strecker synthesis starts with an aldehyde because aldehydes have a reactive carbonyl group that can undergo nucleophilic addition reactions. Using an aldehyde as the starting material allows for the formation of an imine, which can then be hydrolyzed to yield an amino acid.
Step-by-step explanation:
The Strecker synthesis is a method used to synthesize amino acids. It starts with an aldehyde because aldehydes have a reactive carbonyl group that can undergo nucleophilic addition reactions. By using an aldehyde as the starting material, the carbonyl group can react with hydrogen cyanide (HCN) to form an imine, which can then be hydrolyzed to yield an amino acid.
One example of this is the synthesis of glycine, which starts with the aldehyde formaldehyde:
H₂C=O + HCN → H₂C=NH + H₂O
The imine can then be hydrolyzed to give glycine:
H₂C=NH + H₂O → H₂C(NH₂)COOH