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Difference Between Structural Isomers and Stereoisomers

Structural Isomerism

Stereoisomerism

Isomers have the same molecular formula but differ in how the atoms are bonded to each other.

Isomers have the same molecular formula and bonding arrangement; however, they differ in how the atoms are arranged in 3-dimensional space (spatial orientation) with respect to each other.

Such molecules that differ by bonds while still having the same molecular formula are also known as constitutional isomers.

 

These molecules that differ in orientation while still having the same molecular formula are also known as spatial isomers.

 

   Structural Isomerism in Organic Chemistry

Structural isomerism refers to the variation in structures between two or more molecules that have the same molecular formula. The way atoms connect within molecules can even translate into different physical and chemical characteristics. 

In this chapter, we provide an in-depth discussion on how to identify structural isomerism in molecules, covering six major subtypes. 

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Constitutional isomers are further subdivided into 6-types depending on where the variation in the structure exists. 

Stereoisomers are of three types- conformational, geometric and enantiomers.

1. If it is chain length, the isomers are chain isomers.

 

 

2. If the variation is in the position of the functional groups or multiple bonds, the isomers are positional isomers.

 

 

3. Isomers having the same molecular formula, but different functional groups are functional isomers.

 

4. Compounds with the same molecular formula but different carbon atoms on either side of the functional groups are metamers.

 

 

5. Functional group isomers wherein the two isomers rapidly interconvert due to H-atom migration are called tautomers.

 

 

6. Compounds with the same molecular formula but possess open chain and cyclic structures are called ring-chain isomers.

 

 

1. Conformational isomers are same compound that produce infinite variations in their structure due to rotations around the single bonds. However, the most effective rotations responsible for isomers are around the C-C bonds. The relative positions of the groups keep changing with respect to each other. Since the molecules are easily interconvertible by simple bond rotations, isomers are also known as rotamers.

 

 

2. Geometrical isomers have fixed double bonds, and the relative position of groups vary across the double bonds producing isomers. 

 

 

 

3. Enantiomers are optical isomers that use the optical property of reflection. Compounds that are mirror images of each other, however, on stacking them they are non-superimposable, such compounds are called enantiomers. Like the left and the right hands when placed side-by-side are like mirror images of each other. However, when the hands are stacked on top of the other, only the middle fingers match, rest don’t.

 

Structural Isomerism

Organic Chemistry Tutorials - CurlyArrows Premium

What is Organic Chemistry?

  • Introduction
  • Elements of a Chemical Reaction
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Atom

  • Size of an atom- The world belongs to the tiniest!
  • Power of Protons
  • Mass Number
  • Average Atomic Mass
  • Molecule and Molecular Mass
  • The Electrons- An Atom’s Reactive Component
  • Atomic Orbitals- s, p, d, f
  • Filing of Atomic Orbitals and Writing Electronic Configuration
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Bonding In Atoms

  • Octet Rule - Introduction and Bonding
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  • Ionic Bond- Introduction and Formation
  • Formation of Ionic Compound
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  • Appearance and Nature of Ionic Compounds
  • Physical Properties of Ionic Solids- Conductance, Solubility, Melting Point, and Boiling Point
  • Covalent Bond - How it Forms
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  • Covalent Bond - Bond Pair (Single, Double, Triple) and Lone Pair
  • Number of Covalent Bonds- Valency
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Covalent Bond

  • Theories on Covalent Bond Formation
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  • Hybridization- Introduction and Types
  • sp3 Hybridization of Carbon, Nitrogen, and Oxygen
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  • The shape of sp hybrid orbital - Why is the lobe unequal?
  • VSEPR Theory- Introduction
  • Difference between Electron Pair Geometry and Molecular Structure
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  • Predicting Electron-Pair Geometry and Molecular Structure Guideline
  • Predicting Electron pair geometry and Molecular structure - Examples
  • Finding Electron-Pair Geometry and Shape in Multicentre Molecules
  • Drawbacks of VSEPR Theory
  • Electron Wave Property, LCAO and MOT - Introduction
  • Linear Combination of Atomic Orbitals - Formation of Sigma and Pie bonds using MO Approach
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  • Conditions for the Valid Linear Combination of Atomic Orbitals  
  • Features of LCAO Theory
  • Finding the Electronic Configuration of Molecules using MO and Predicting Comparative Stability using Bond Order
  • Setting up the MO diagram for homonuclear diatomic molecules – Second Period Elements
  • Setting up the Molecular Orbital Diagram for Heteronuclear Diatomic Molecules
  • The Non-bonding Molecular Orbitals
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  • Covalent bond Characteristics - Bond Length
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Electronic Displacement in a Covalent Bond

  • Electronegativity- Introduction
  • Factors Affecting Electronegativity- Atomic number, Atomic size, Shielding effect
  • Factors Affecting Electronegativity-s-orbitals, Oxidation state, Group electronegativity
  • Application of Electronegativity in Organic Chemistry
  • Physical Properties Affected by Electronegativity
  • Inductive effect - Introduction, Types, Classification, and Representation
  • Factors Affecting Inductive Effect- Electronegativity
  • Factors Affecting Inductive Effect- Bonding Order and Charge
  • Factors Affecting Inductive Effect- Bonding Position
  • Application of Inductive Effect- Acidity Enhancement and Stabilization of the counter ion due to -I effect
  • Application of Inductive Effect-Basicity enhancement and stabilization of the counter ion due to +I effect
  • Application of Inductive Effect-Stability of the Transition States
  • Application of Inductive Effect-Elevated Physical Properties of Polar Compounds
  • Is the Inductive Effect the same as Electronegativity?
  • Resonance - Introduction and Electron Delocalization
  • Partial Double Bond Character and Resonance Hybrid
  • Resonance Energy
  • Significance of Planarity and Conjugation in Resonance
  • p-orbital Electron Delocalization in Resonance
  • Sigma Electron Delocalization (Hyperconjugation)
  • Significance of Hyperconjugation
  • Resonance Effect and Types
  • Structure Drawing Rules of Resonance (Includes Summary)
  • Application of Resonance
  • Introduction to Covalent Bond Polarity and Dipole Moment
  • Molecular Dipole Moment
  • Lone Pair in Molecular Dipole Moment
  • Applications of Dipole Moment
  • Formal Charges - Introduction and Basics
  • How to Calculate Formal Charges (With Solved Examples)
  • Difference between Formal charges and Oxidation State

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Common Types of Reactions

  • Classification of common reactions based on mechanisms
  • Addition Reactions
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Drawing Organic Structures

  • Introduction
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  • Hill Nomenclature - The Empirical and Molecular Formula Writing Rules
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  • Newman Projection- Introduction and Importance
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Functional Groups in Organic Chemistry

  • What are functional groups?
  • Chemical and Physical Properties affected by the Functional Groups
  • Identifying Functional Groups by name and structure
  • Functional Group Categorization- Exclusively Carbon-containing Functional Groups
  • Functional Group Categorization- Functional Groups with Carbon-Heteroatom Single Bond
  • Functional Group Categorization- Functional Groups with Carbon-Heteroatom Multiple Bonds
  • Rules for IUPAC nomenclature of Polyfunctional Compounds
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Structural Isomerism

  • Introduction
  • Chain Isomerism
  • Position Isomerism
  • Functional Isomerism
  • Tautomerism
  • Metamerism
  • Ring-Chain Isomerism

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Intermolecular Forces

  • Ion-Dipole Interactions-Introduction and Occurrence
  • Factors Affecting the Ion-Dipole Strength
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  • Ion-Induced Dipole - Introduction, Strength and Occurrence
  • Factors Affecting the Strength of Ion-Induced Dipole Interactions
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  • Vander Waals Forces -Introduction
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  • Factors Affecting the Strength of London Dispersion Forces- Atomic size and Shape
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Physical Properties

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Fundamentals of Organic Reactions

  • Types of Arrows Used in Chemistry
  • Curved Arrows in Organic Chemistry- with Examples
  • Electrophiles - Introduction, Identification and Reaction
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  • Using pKa as a Measure of Leaving Group Ability
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Reactive Intermediates

  • Carbocation - Introduction, Nature, and Types
  • Formation of Carbocation
  • Stability of Carbocations- Inductive, Resonance, and Hyperconjugation
  • Other Structural Features Increasing Carbocation Stability
  • Structural Feature Decreasing Carbocation Stability
  • Fate of the Carbocation
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  • Carbanion - Introduction, Nature, and Types
  • Formation of Carbanions
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  • Ease of Formation of Carbanion -Acidic proton
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  • Free Radical - Introduction and Types of Carbon-Centred Radicals
  • Structure of Carbon-Centred Free Radical
  • Formation of Radicals
  • Stability of the Carbon-Centred Radicals
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  • Comparing Free Radical Stability using Dissociation energies (D-H)
  • Fate of Free Radicals
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Stereoisomerism - Conformation and Configurational Isomerism

  • Conformations in Organic Chemistry - An Introduction
  • How are Conformational Isomers Depicted
  • Open Chain and Closed Chain Conformations
  • Nomenclature related to sp3-sp3 and sp3-sp2 bond rotations
  • Conformational Analysis
  • Factors affecting the stability of conformers - Stabilizing Interactions |Hyperconjugation
  • Factors affecting the stability of conformers - Stabilizing Interactions | Intramolecular Hydrogen Bonding
  • Factors affecting the stability of conformers - Stabilizing Interactions | Dipole Minimizations
  • Factors affecting the stability of conformers - Destabilizing Interactions | Steric strain
  • Factors affecting the stability of conformers - Destabilizing Interactions | Torsional strain
  • Factors affecting the stability of conformers - Destabilizing Interactions | Angle strain
  • Importance of Conformational Analysis
  • Conformation in Compounds with Lone Pairs
  • Role of Solvents in Conformations
  • An Example of Conformation Dependent Reaction and Product Selectivity
  • Geometrical Isomerism - Introduction
  • Impact of cis-trans isomerism on physical properties
  • Impact of cis-trans isomerism on chemical reactions
  • Scope of Geometrical Isomerism in Biological Systems and Industrial Applications
  • E/Z Nomenclature in Substituted Alkenes
     

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