Undergraduate
  1. General chemistry  1.1. Introduction to Chemistry  1.2. Atomic Structure  1.2.1. Subatomic particles  1.2.2. Atomic Model  1.2.3. Quantum numbers  1.2.4. Electron Configuration  1.2.5. Periodic trends  1.2.6. Isotopes and their applications  1.3. Chemical bond  1.3.1. Ionic bond  1.3.2. Covalent bonds  1.3.3. Metal Bond  1.3.4. Hybridization  1.3.5. Molecular geometry and VSEPR theory  1.3.6. Bond polarity and dipole moment  1.4. Stoichiometry  1.4.1. Mole concept  1.4.2. Empirical and molecular formula  1.4.3. Limiting reactant and excess reactant  1.4.4. Percent Yield and Purity  1.4.5. Dilution calculation  1.5. States of matter  1.5.1. Gas Laws  1.5.2. Matter and Intermolecular Forces  1.5.3. Solid and Crystal Structures  1.5.4. Phase diagram  1.5.5. Plasma and supercritical fluid  1.6. Chemical reactions  1.6.1. Types of Chemical Reactions  1.6.2. Balancing Chemical Equations  1.6.3. Thermochemical reactions  1.6.4. Reaction energy profiles  1.7. Solutions and Mixtures  1.7.1. Concentration units  1.7.2. Syndrome properties  1.7.3. Solubility and Solubility Rules  1.7.4. Henry's Law and Raoult's Law  1.7.5. Partition coefficient  1.8. Chemical equilibrium  1.8.1. Law of mass action  1.8.2. Le Chatelier's principle  1.8.3. Reaction quotient  1.8.4. To use this online calculator for Equilibrium Constant, enter Equilibrium Constant (Eq.) and hit the calculate button. Here is how the Equilibrium Constant calculation can be explained with given input values -> 0.05 = 0.05/0.  1.8.5. Acid-base balance  1.9. Acids and bases  1.9.1. Arrhenius, Brønsted–Lowry, and Lewis definitions  1.9.2. pH and pOH  1.9.3. Acid-base titration  1.9.4. Buffer Solution  1.9.5. Acid-base indicator  1.9.6. Polyprotic Acids and Bases  1.10. Electrochemistry  1.10.1. redox reactions  1.10.2. Galvanic and Electrolytic Cells  1.10.3. Nernst equation  1.10.4. Electrolysis  1.10.5. Faraday's laws of electrolysis  1.11. Thermodynamics  1.11.1. Laws of Thermodynamics  1.11.2. Enthalpy, entropy and Gibbs free energy  1.11.3. Spontaneity of reactions  1.11.4. Thermodynamic cycles (Hess's law, Carnot cycle)  1.12. Kinetics  1.12.1. Rate law and reaction order  1.12.2. Activation Energy and Catalyst  1.12.3. Collision theory  1.12.4. Reaction mechanism  1.12.5. Transition state theory
  2. Organic chemistry  2.1. Structure and relationships  2.1.1. Hybridisation in Carbon Compounds  2.1.2. Resonance and aromatization  2.1.3. Molecular orbitals  2.1.4. Inductive and mesomeric effects  2.2. Hydrocarbons  2.2.1. Hydrocarbons  2.2.2. Alkene  2.2.3. Alkynes  2.2.4. Aromatic compounds  2.2.5. Cycloalkanes and Conformation  2.3. Functional Group  2.3.1. Alcohols and phenols  2.3.2. Ethers and epoxides  2.3.3. Aldehyde and ketone  2.3.4. Carboxylic acids and derivatives  2.3.5. Amin  2.3.6. Esters and amides  2.3.7. Thiols and sulfides  2.4. Stereoscopic  2.4.1. Isomerism in Stereochemistry  2.4.2. Chirality and optical activity  2.4.3. Structural analysis  2.4.4. Diastereomers and Enantiomers  2.5.1. Substitution reactions  2.5.2. Elimination reactions  2.5.3. Addition reactions  2.5.4. Radical reactions  2.5.5. Rearrangement reactions  2.5.6. Pericyclic Reactions  2.6. Spectroscopy and structural analysis  2.6.1. Infrared Spectroscopy  2.6.2. Nuclear magnetic resonance spectroscopy  2.6.3. Mass Spectrometry  2.6.4. UV-visible spectroscopy  2.6.5. X-ray crystallography  2.7. Polymer chemistry  2.7.1. Addition and Condensation Polymers  2.7.2. Polymerization mechanism  2.7.3. Biodegradable Polymer  2.7.4. Conducting and smart polymers
  3. Inorganic chemistry  3.1. Coordination chemistry  3.1.1. Ligands and coordination compounds  3.1.2. Crystal field theory  3.1.3. Molecular Orbital Theory in Coordination Compounds  3.1.4. Jahn–Taylor distortion  3.2. Main Group Chemistry  3.2.1. Alkali and alkaline earth metals  3.2.2. Halogens and Noble Gases  3.2.3. Transition metals and their complexes  3.2.4. Lanthanides and Actinides  3.3. Solid state chemistry  3.3.1. Crystal lattices and unit cells  3.3.2. Defects in solids  3.3.3. Electrical and magnetic properties  3.3.4. Superconductivity  3.4. Bio-inorganic chemistry  3.4.1. Metal ions in biology  3.4.2. Enzymatic reactions with metals  3.4.3. Metal poisoning and detoxification  3.4.4. Metalloproteins and Metalloenzymes
  4. Physical chemistry  4.1. Quantum Chemistry  4.1.1. Wave–particle duality  4.1.2. Schrödinger Equation  4.1.3. Quantum Numbers and Orbitals  4.1.4. Atomic and molecular spectroscopy  4.2. Statistical mechanics  4.2.1. Maxwell–Boltzmann distribution  4.2.2. Partitioning functions  4.2.3. Bose–Einstein and Fermi–Dirac statistics  4.3. Chemical thermodynamics  4.3.1. Gibbs Free Energy  4.3.2. Phase transition  4.3.3. Thermodynamic efficiency  4.4. Surface chemistry  4.4.1. Absorption and Catalysis  4.4.2. Colloids and Emulsions
  5. Analytical Chemistry  5.1. Classical methods  5.1.1. Gravimetric Analysis  5.1.2. titrimeter  5.2. Instrumental methods  5.2.1. Chromatography  5.2.2. Spectroscopy  5.2.3. Electroanalytical methods  5.2.4. X-ray diffraction
  6. Industrial Chemistry  6.1. Petrochemistry  6.2. Chemical engineering principles  6.3. Green Chemistry  6.4. Pharmaceuticals and Drug Synthesis
  7. Biochemistry  7.1. Carbohydrates  7.2. Proteins and enzymes  7.3. Lipids and membranes  7.4. Nucleic acids  7.5. Metabolism and Bioenergetics  7.6. Enzyme kinetics and mechanism

Undergraduate → Organic chemistry → Stereoscopic ↓


Isomerism in Stereochemistry


In the world of chemistry, especially organic chemistry, the concept of isomerism plays an important role in understanding the diversity and behavior of molecules. Isomers are compounds that have the same molecular formula but are arranged differently in space. These differences in arrangement affect the physical and chemical properties of compounds. Stereochemistry is a sub-discipline of chemistry that involves the study of the spatial arrangement of atoms within molecules. Stereochemistry is central to understanding isomerism.

Types of isomerism

Isomerism may be broadly classified into two types:

  • Structural isomerism
  • Stereoisomerism

Structural isomerism involves the difference in the valency of atoms, while stereo isomerism involves only the difference in the spatial arrangement. In this article, we will learn about stereo isomerism in detail.

Stereoisomerism

Stereoisomers have the same order of bonded atoms (structure), but they differ in the three-dimensional orientation of their atoms in space. It can be further divided into:

  • Geometrical isomerism
  • Optical isomerism

Geometrical isomerism

Geometrical isomerism, also known as cis-trans isomerism, arises due to restricted rotation about a bond, commonly found in doubly bonded atoms or ring structures.

In cis isomers the two substituents are on the same side, while in trans isomers they are on opposite sides.

Visual example of geometric isomerism

cis-2-butene and trans-2-butene:

Cis-2-butene: CH3 | H --C==C-- H | CH3 
Trans-2-butene: CH3 | H --C==C-- CH3 | H

Optical isomerism

Optical isomerism arises from the presence of chiral centers in molecules. A chiral molecule is one that cannot be superimposed on its mirror image. Such molecules are said to have chirality.

Each pair of superimposed mirror-image molecules is called an enantiomer.

Visual example of optical isomerism

Simple chiral molecules:

Chiral Carbon (C*): R1 | R2--C*--R3 | R4

Where C* is a chiral (asymmetric) carbon atom bonded to four different groups (R1, R2, R3, and R4).

Enantiomers

Enantiomers are optical isomers that are mirror images of each other but cannot be aligned to be identical. They affect how light rotates when it passes through a compound, and this property is called optical activity.

When a solution containing the enantiomer rotates the plane of polarized light to the right, it is called the (+)-enantiomer or dextrorotary. If it rotates the light to the left, it is called the (−)-enantiomer or levorotary.

Diastereomers

Not all stereoisomers are enantiomers. When isomers are not mirror images of each other, they are called diastereomers. They have different physical and chemical properties and they do not rotate plane-polarized light the same way.

Example of diastereomers

Consider a compound with two chiral centers:

Compound with Two Chiral Centers: (1R, 2R) and (1S, 2R)
H   OH
  / 
  C  
 /  
OH  H

These structures are examples of diastereomers.

Meso compounds

Meso compounds are a subtype of stereoisomers that are achiral despite having multiple chiral centers. This is because they have an internal plane of symmetry that divides the molecule into two mirror-image halves, which makes them optically inactive.

For example:

Meso Compound Example: 
HO   OH
  / 
  C (Internal plane of symmetry)
 /  
HO  OH

Implications of stereochemistry in biological systems

Stereochemistry is important in biological systems because many biological molecules are chiral. Enzymes, receptors, and other proteins often distinguish between different enantiomers. For example, many drugs are chiral and the desired therapeutic effect usually comes from one specific enantiomer, while the other may be inactive or even harmful.

Conclusion

The study of stereochemistry and isomerism opens up a rich landscape in understanding chemistry and molecular interactions. By considering how atoms are oriented in space, chemists can design molecules with specific functions or interactions, predict reactivity, and explore biochemical pathways. This underscores the importance of stereochemistry in both industrial applications and academic research in chemistry.


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Isomerism in Stereochemistry

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