Isomers are the organic chemistry phenomenon with two or more compounds and the same quantitative and qualitative composition; instead, it has different biological, chemical, and physical properties.
The various properties occur because of the constitution or stereoisomerism of the organic molecules.
Key Takeaways
- Constitutional isomers are compounds with the same molecular formula but different structures, while stereoisomers have the same molecular formula and structure but different spatial arrangements.
- Constitutional isomers differ in the order of attachment of atoms or groups, while stereoisomers differ in the orientation of atoms or groups in three-dimensional space.
- Constitutional isomers can have different physical and chemical properties, whereas stereoisomers have identical physical and chemical properties.
Constitutional Isomers vs Stereoisomerism
Constitutional isomers have the same molecular formula but differ in their connectivity of atoms and can be differentiated by their functional groups and the way they are connected. Stereoisomers have the same molecular formula and connectivity of atoms but differ in their spatial arrangement.
Constitutional isomers are also known as structural isomers. It is a form of isomer where molecules with the properties of the same molecules create a bond in different orders to oppose stereoisomerism. It is a compound with the same molecular formula yet a different structural formula.
Stereoisomers can also be known as spatial isomers. It has quantitative, qualitative, and functional structures rather than having a different spatial orientation of molecules or their parts. Spatial isomers are different because they have different spatial symmetries of molecules.
Comparison Table
| Parameter of Comparison | Constitutional isomers | Stereoisomers |
|---|---|---|
| Meaning | Constitute isomers have a different structure but the same molecular formula. | Stereoisomers are the same molecular functional and formula structure with different spatial orientations of molecules. |
| Types | ||
| Chirality | In constitutional isomers, chirality is absent | In stereoisomers, chirality is present. |
| Arrangement | In constitutional isomers, the arrangement of an atom is different. | In stereoisomers, the arrangement of an atom is the same. |
| Properties | In constitutional isomers, molecules’ properties are different from each other. | In stereoisomers, the properties of the molecules are mainly similar. |
What are the Constitutional Isomers?
Constitutional isomers are known as structural isomers. It is a compound with a different structure but has the same molecular formula. Different types of constitutional or structural isomers exist, like functional groups, positions, and skeletal.
Skeletal isomers have different physical properties. It has uniform qualitative, quantitative and functional composition rather than a different chain of molecules. This chain can also be different or straight-branched.
The positional isomers have different locations of the chain’s substituent, complex bond, or functional group. The positional isomers have different physical properties, and some of them also are biochemical ones. Metamerism is known as the form of positional isomers.
The isomers with the same qualitative and quantitative but different functional groups are known as functional isomers. If there is a difference in function groups, this will also lead to their different chemical properties.
Some good examples of functional isomers are fructose and glucose. It is also believed that functional isomers have different biochemical importance.
Another main type of structural isomerism is tautomerism, where under some conditions, some spatial structure can be translated into another alongside dynamic equilibrium between them. This isomer can also be known as a form of functional isomer.
What is Stereoisomerism?
Stereoisomers can also be known as spatial isomers. It has quantitative, qualitative, and functional structures rather than having a different spatial orientation of molecules or their parts.
Spatial isomers are different because they have different spatial symmetries of molecules. Some main elements of symmetry are the axis, plane, and centre.
The stereoisomers can also be geometric, optical, conformational isomers, and configurational isomers. Geometric isomers have a different spatial arrangement of substituents relative to the symmetry plane.
Geometric isometry has the possibility of a substitute group in which one side is a double bond plane, non-aromatic cycle, or Na different side. The isomers with two identical substituents on one side of the plane are known as cis-isomer, and another side of the plane is known as trans-isomer.
It is to be believed that in optical isomers, the molecules have no axis, no centre, and no plane of symmetry. Optical isomers have asymmetric types of molecules. The optical isomers are also known as enantiomers, whose biological meaning is different.
Optical isomers have the same chemical properties but have different optical activities.
Spatial isomerism is an isomer with the same configuration; instead, they have different spatial orientations because it is known as conformational.
The different isomers result in the breakage of the bond and the rotation of different molecule types over the axis of a simple sigma bond, and the displacement of the substituents. If the resulting isomers have different conformations, they are known as conformers.
Main Differences Between Constitutional Isomers and Stereoisomers
- Constitutional and stereoisomers differ only in the group’s spatial orientation in the molecules.
- A constitutional isomer is a compound with different structural formulas. On the other hand, stereoisomers are the same molecular functional and formula structure with different molecules’ spatial orientations.
- The constitutional or structural isomers can be positional, functional, or skeletal group isomers. On the other hand, stereoisomers have been configurational( optical, geometric) and conformational isomers.
- Constitutional or structural isomers have different properties. On the other hand, stereoisomers have similar properties.
- Constitutional isomers mainly have different chemical names. On the other hand, stereoisomers have mainly the same chemical name with the same letter or symbol in front of the name to identify the orientation.
- In constitutional isomers, the arrangements of an atom are mainly the same. On the other hand, stereoisomers have the same arrangement of the atom.
- In constitutional isomers, chirality is absent. On the other hand, in stereoisomers, chirality is present.
- https://pubs.acs.org/doi/abs/10.1021/ci9502663
- https://www.chinesechemsoc.org/doi/abs/10.31635/ccschem.020.201900094
Last Updated : 11 June, 2023
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The comparison provided between constitutional and stereoisomers is very clear and helps to solidify the understanding of the differences. I appreciate the clarity of this article, making it easier to comprehend.
I echo your sentiment, Kprice. The article effectively elucidates the distinguishing features of these isomers, allowing for a thorough comprehension that can be challenging to grasp in textbook definitions.
Absolutely, Kprice. The lucid comparison table is particularly useful for quick reference and serves as an excellent visual aid for understanding the disparities between these isomers.
The article does a fantastic job of explaining tautomerism and its significance. I appreciate the comprehensive coverage of this aspect, which is overlooked in discussions of isomerism.
I concur, Tanya Scott. The inclusion of tautomerism further enhances the depth of knowledge provided by the article, offering a holistic understanding of various forms of isomerism.
The detailed examples of different types of structural isomers are particularly insightful. It provides a real-world perspective that enhances the understanding of this topic.
Absolutely, Trichards. The explanation of functional isomers using fructose and glucose as examples makes this complex concept more tangible for readers. It’s a commendable approach in clarifying such abstract ideas.
The article offers a comprehensive exploration of the nuanced differences between isomers. It effectively addresses both conceptual frameworks, providing clarity within this complex domain of organic chemistry.
I completely agree, Davis Hollie. The meticulous dissections of constitutional and stereoisomers within the article amplify the readers’ grasp of these concepts and offer a deeper appreciation for the intricacies of isomerism.
While the article presents complex concepts, it does so in a highly readable and articulate manner. The detailed explanations and categorization of isomers make it a valuable resource for those studying organic chemistry.
I share your perspective, Tara72. The sophisticated yet accessible language used in the article makes it an engaging read for experts and novices alike, fostering a deeper understanding of isomerism.
The thorough analysis of isomerism presented in the article is both insightful and engaging. It serves as a commendable resource for those in the field of organic chemistry and related disciplines.
I couldn’t agree more, Harrison Philip. The article’s systematic breakdown of isomerism undoubtedly enriches the readers’ understanding and appreciation of the diverse manifestations of this chemical phenomenon.
Absolutely, Harrison Philip. The article’s coverage of isomers, spanning from conceptual foundations to real-world examples, is indeed praiseworthy, encapsulating the complexities of this subject in a compelling manner.
The detailed overview of stereochemistry and the explanations of spatial isomers are enlightening. It’s great to see such a thorough exploration of this subject, shedding light on its intricacies.
Absolutely, Paul James. The article strikes a balance between technicality and comprehensibility, making it an invaluable resource for individuals seeking to delve deeper into the complexities of stereochemistry.
The article is very informative when discussing isomers and the difference between constitutional and stereoisomers. The key takeaways section is particularly helpful to understand the main concepts.
I agree with you, Mary88. The various properties that emerge from the constitution or stereoisomerism of organic molecules can be quite complex, so it’s great that the article provides a clear explanation of the differences.
The distinction between constitutional and stereoisomers is well-presented here, and the comparison table effectively summarizes the key differences. This is definitely a useful reference for students and professionals in the field.
While the article provides an in-depth overview of isomerism, it can be quite overwhelming for those new to the subject. A more simplified introduction might be beneficial for beginners.
I can see your point, Damien26. Perhaps a concise summary at the beginning of the article to outline the fundamental concepts before delving into the specifics would make it more approachable for beginners.
I somewhat disagree with your view, Damien26. This article is precisely tailored for those who already have a foundation in organic chemistry, and it does an excellent job of breaking down complex principles into manageable segments.
I found the section on stereoisomerism to be highly elucidating, especially the explanation on the different types of stereoisomers. It provides a comprehensive understanding of this intricate topic.
I completely agree, Price Barry. The in-depth coverage of geometric, optical, and conformational isomers is particularly enriching, offering a robust foundation in comprehending this aspect of isomerism.