Enantiotopic vs. Diastereotopic — What's the Difference?
Edited by Tayyaba Rehman — By Fiza Rafique — Updated on May 15, 2024
Enantiotopic refers to hydrogen atoms in a molecule that are interchangeable by symmetry, whereas diastereotopic hydrogens are not symmetrical and have different chemical environments.
Difference Between Enantiotopic and Diastereotopic
Table of Contents
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Key Differences
Enantiotopic hydrogens are present in a symmetrical environment where one can be replaced by another without changing the molecule’s overall symmetry. Whereas diastereotopic hydrogens reside in an asymmetrical environment, leading to molecules that are not superimposable on their mirror images when one hydrogen is replaced.
In terms of NMR spectroscopy, enantiotopic hydrogens appear as a single signal, indicating identical chemical environments. On the other hand, diastereotopic hydrogens show different signals, reflecting their non-equivalent chemical surroundings.
Enantiotopic groups often occur in achiral or symmetric molecules, where swapping one group for another does not result in a new chiral center. Conversely, diastereotopic groups are typically found in chiral molecules where such substitutions result in diastereomers.
When considering reactions, enantiotopic atoms react identically with achiral reagents; however, they can behave differently with chiral reagents. In contrast, diastereotopic atoms always exhibit different reactivities, even with achiral reagents, due to their distinct spatial arrangements. This distinction is crucial in stereochemical studies and organic synthesis, where understanding the specific type of hydrogen atoms involved can influence the outcome of reactions.
Comparison Chart
Symmetry
Symmetrical environment
Asymmetrical environment
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NMR Signal
Single signal due to identical environments
Different signals due to distinct environments
Occurrence in Molecules
Typically in achiral or symmetric molecules
Common in chiral molecules
Effect of Substitution
Does not create new chiral centers
Can result in diastereomers
Reactivity with Reagents
Identical with achiral reagents; varies with chiral reagents
Different reactivities, even with achiral reagents
Compare with Definitions
Enantiotopic
Pertains to two atoms or groups within a molecule that are interchangeable by symmetry.
In ethane, the two methyl groups are enantiotopic.
Diastereotopic
Exchange results in diastereomers, not identical compounds.
Swapping diastereotopic hydrogens in lactic acid produces different diastereomers.
Enantiotopic
Atoms or groups whose exchange does not lead to a chiral molecule.
The hydrogens in methane are enantiotopic since swapping them does not produce chirality.
Diastereotopic
Exhibits different physical and chemical properties.
Diastereotopic hydrogens in chiral molecules display different chemical shifts in NMR spectroscopy.
Enantiotopic
Exhibits identical physical and chemical properties in an achiral environment.
Enantiotopic hydrogens in symmetric molecules show the same reactivity towards achiral reagents.
Diastereotopic
Identified in NMR spectroscopy by distinct resonance peaks.
Diastereotopic hydrogens can be distinguished by their separate signals in an NMR spectrum.
Enantiotopic
Does not affect the molecule’s chirality upon substitution.
Substituting one enantiotopic hydrogen for a deuterium in an achiral molecule retains the molecule's achirality.
Diastereotopic
Refers to atoms or groups in a molecule that are in different chemical environments and not interchangeable by symmetry.
In 1,3-dichloropropane, the central methylene hydrogens are diastereotopic.
Enantiotopic
Identified in NMR spectroscopy by a single resonance peak.
Enantiotopic groups in a molecule contribute to a single signal in an NMR spectrum.
Diastereotopic
Affects the molecule’s stereochemical configuration upon substitution.
Substituting one diastereotopic hydrogen for a deuterium in chiral molecules can change the molecule’s configuration.
Enantiotopic
(chemistry) Describing the relationship between two groups attached to the same atom which, if replaced, would generate compounds that are enantiomers
Diastereotopic
(chemistry) Describing any atom, ligand, or other group in a molecule whose replacement or addition gives rise to diastereomers
Common Curiosities
Can enantiotopic and diastereotopic hydrogens be distinguished by NMR spectroscopy?
Yes, enantiotopic hydrogens typically appear as a single signal, while diastereotopic hydrogens show separate signals in NMR spectroscopy.
What defines an enantiotopic group in a molecule?
Enantiotopic groups are two groups within a molecule that are interchangeable and reside in symmetrical environments.
What is the significance of diastereotopic groups in stereochemistry?
Diastereotopic groups are crucial for understanding stereochemical relationships and reactivity in chiral molecules.
How do diastereotopic groups differ from enantiotopic groups in their chemical environment?
Diastereotopic groups are not interchangeable and exist in different chemical environments within the same molecule.
How does substitution affect enantiotopic versus diastereotopic hydrogens?
Substituting enantiotopic hydrogens does not alter chirality, whereas substituting diastereotopic hydrogens can result in diastereomers.
In what types of molecules are diastereotopic hydrogens more common?
Diastereotopic hydrogens are more commonly found in chiral molecules.
How are enantiotopic groups relevant in pharmaceutical synthesis?
Enantiotopic groups in achiral precursors can influence the synthesis and properties of chiral drugs.
Are enantiotopic hydrogens found only in symmetric molecules?
Primarily, yes, enantiotopic hydrogens are found in symmetric molecules where their interchange does not affect the molecule’s symmetry.
Can diastereotopic groups affect the outcome of chemical reactions?
Yes, due to their different chemical environments, diastereotopic groups can influence the pathway and product of chemical reactions.
How do diastereotopic hydrogens contribute to the study of complex organic molecules?
They provide insights into the molecular structure and stereochemical composition, essential for organic synthesis and analysis.
What impact does chirality have on enantiotopic and diastereotopic groups?
Chirality affects diastereotopic groups significantly, altering their physical and chemical properties, whereas enantiotopic groups remain unaffected in terms of chirality.
Can diastereotopic groups lead to different pharmacological effects?
Yes, because they can form different stereoisomers, each possibly having distinct biological activities.
What methodologies are used to identify enantiotopic and diastereotopic hydrogens in a laboratory?
NMR spectroscopy is a primary tool used to identify and distinguish between enantiotopic and diastereotopic hydrogens based on their chemical environments.
Why is it important to distinguish between enantiotopic and diastereotopic in molecular modeling?
Distinguishing between these groups aids in predicting molecular behavior and interactions, crucial in drug design and material science.
What role do enantiotopic groups play in material science?
Enantiotopic groups can affect the physical properties and assembly of materials at the molecular level.
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Fiza RafiqueFiza Rafique is a skilled content writer at AskDifference.com, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.
Edited by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
