Sequence Rules (Cahn–Ingold–Prelog Rules)

• Sequence Rules (Cahn–Ingold–Prelog Rules) assign R or S configuration to chiral centers based on priority of substituent groups.
• These rules are used to assign priorities to groups around a chiral center when determining R/S configurations.

Sequence Rules:

1. Priority by atomic number:

   • Higher atomic number = higher priority.
   • I > Br > Cl > S > F > O > N > C > H

2. If two atoms directly attached are the same:

   • Move to the next atoms along the chain until a difference is found.

3. Multiple bonds are treated as multiple single bonds:

   • A double bond to oxygen is treated as being bonded to two single-bonded oxygens.

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