Help Centre
References and Formatting
Substituent Notation

Substituent Notation

Why does Reaction Repo use ‘R’ only instead of ‘R¹’, ‘R²’, etc., for some entries?
Reaction Repo uses ‘R’ only when there is a single substituent involved in the reaction. This simplifies notation, ensuring clarity and generalization, as it indicates that any alkyl or aryl group can be present without specifying different substituents.
Why do some textbooks, such as ‘Organic Chemistry’ by Clayden, Greeves, and Warren, not use ‘R¹’ and ‘R²’ for some reactions?
Textbooks often choose not to use “R¹” and “R²” when the specific nature of the substituents is not critical to the reaction being discussed. By using a single “R”, they simplify the presentation and make it easier for students to grasp the fundamental concepts. When the identity of the substituents does matter, textbooks will typically provide more detailed notation and explanations.
How should I approach reactions where ‘R¹’ and ‘R²’ are used but not explained?

When encountering reactions with “R¹” and “R²” that are not explained, you should:

  • Assume that the substituents could be different and consider if the reaction outcome might vary with different substituents.
  • Look for additional context in the surrounding text or resources.
  • Understand that the core mechanism or outcome depicted is meant to be general and broadly applicable.
Why is there inconsistency in the use of substituent notation across different educational resources?
The inconsistency arises from different teaching approaches and the varying levels of detail required for specific discussions. Some resources aim to simplify concepts for easier understanding, while others provide detailed notations to cover all potential scenarios. The choice of notation often depends on the target audience and the educational goals of the resource.
What should I do if I’m confused by the notation used in a reaction diagram?

If you’re confused by the notation:

  • Refer to the surrounding text or additional resources for clarification.
  • Consider the general mechanism being shown and whether the specifics of the substituents are likely to impact the reaction.
  • Reach out to instructors or peers for further explanation and context.