IUPAC Naming of Branched Alkanes

Overview

• Presenter: Leah from leah4sci.com
• Topic: IUPAC rules for naming branched alkanes

Basic Rules for Naming Branched Alkanes

1. Identify Parent Chain:

   • Longest continuous carbon chain in the molecule.
   • Trace without lifting the highlighter.

2. Number the Chain:

   • Number so that substituents have the lowest possible numbers.

3. Name Parent and Substituents:

   • Include number for each substituent's position on parent chain.
   • Use prefixes for carbon number in substituent + 'yl' (e.g., methyl for 1 carbon).
   • Indicate quantity of each substituent (di-, tri-, tetra-, penta-).

Examples

Example 1: 2-Methylbutane

• Parent Chain: Longest chain with 4 carbons, named "butane".
• Substituent: 1 carbon at position 2, named "methyl".
• Final Name: 2-methylbutane.

Example 2: 2,2-Dimethylbutane

• Parent Chain: 4 carbons, "butane".
• Substituents: Two methyl groups at position 2.
• Numbering: 2,2-dimethyl to indicate two methyl groups at position 2.
• Final Name: 2,2-dimethylbutane.

Example 3: 5-Ethyl-2-methylheptane

• Parent Chain: 7 carbons, "heptane".
• Substituents:
  • 1 carbon at position 2 (methyl).
  • 2 carbons at position 5 (ethyl).
• Naming Order: Alphabetical (ethyl before methyl).
• Final Name: 5-ethyl-2-methylheptane.

Example 4: 3-Ethylhexane

• Parent Chain: 6 carbons, "hexane".
• Substituent: 2 carbons at position 3 (ethyl).
• Final Name: 3-ethylhexane.

Example 5: 4-Ethyl-2,3,6-trimethylheptane

• Parent Chain: 7 carbons, "heptane".
• Substituents:
  • Methyl groups at positions 2, 3, and 6.
  • Ethyl at position 4.
• Numbering and Order:
  • Alphabetical order (ethyl before methyl).
  • 2,3,6-trimethyl indicates three methyl groups.
• Final Name: 4-ethyl-2,3,6-trimethylheptane.

Additional Guidance

• Junction Rule: Helps identify longest carbon chain by analyzing junction points.
• Numbering Conventions:
  • Commas separate numbers.
  • Dashes separate numbers from letters.

Resources

• e-Book: "10 Secrets to Acing Organic Chemistry" available at leah4sci.com/orgosecrets.
• Online Tutoring: Visit leah4sci.com/orgotutor.

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These notes summarize the key concepts and examples from the video on naming branched alkanes using IUPAC rules. For further details and examples, refer to the video or additional resources provided by Leah at Leah4sci.