Naming Aldehydes: Lecture Notes

Introduction

• Focus on naming a specific aldehyde structure.
• Importance of identifying the longest carbon chain first.

Steps for Naming Aldehydes

Step 1: Identify the Longest Carbon Chain

• Find the longest continuous chain of carbon atoms.
• Example given with a 5-carbon chain.
• Classify this chain as pentane.

Step 2: Modifying the Parent Chain Name

• For aldehydes, drop the "e" at the end of the parent chain name and replace it with "al".
  • e.g., "pentane" becomes "pental".
• This gives the aldehyde the name pentanal.

Step 3: Identify and Name Substituents

• Example substituent: phenyl group at carbon 2.
• Important to distinguish between phenyl groups and benzaldehydes:
  • Phenyl group: No direct attachment between the benzene ring and the aldehyde group.
  • Benzaldehyde: Direct connection between benzene ring and aldehyde group.

Step 4: Numbering the Carbon Chain

• When numbering, start from the end nearest to the aldehyde group.
• This ensures the substituents are numbered correctly.

Step 5: Construct the Full Name

• Combine substituent location and name with the parent chain name.
• Final structure name in the example: 2-phenyl-pentanal.

Key Considerations

• Understand the distinction between direct and indirect attachments between components in the structure.
• Follow the rules for naming to accurately describe chemical structures.

Conclusion

• Naming of aldehydes involves identifying the longest chain, modifying the chain name, identifying substituents, and combining these elements into a coherent name.
• Example provided for clarity: 2-phenyl-pentanal.

These notes capture the essential elements of naming aldehydes with a focus on the structure and substituents, providing clear steps and examples for clarity.