Conditions for Optical Activity require the presence of a chiral center, absence of symmetry, and a non-superimposable mirror image. Conditions for Optical Activity To be optically active, a compound (including biphenyl atropisomers) must meet the following: Chirality Must be non-superimposable on its mirror image. Can arise from: Chiral centers Axial, planar, or helical chirality No … Read more

Stereoisomerism in Biphenyl Compounds (Atropisomerism) Stereoisomerism in Biphenyl Compounds (Atropisomerism) occurs when restricted rotation around the biphenyl bond creates stable, isolable isomers with distinct properties. What is Biphenyl? Biphenyl is a molecule made of two benzene rings joined by a single bond: The two rings can rotate around the central C–C bond. However, rotation can … Read more

Conformational Isomerism in Cyclohexane Conformational Isomerism in Cyclohexane (C₆H₁₂) involves chair, boat, twist, and half-chair forms, with the chair conformation being the most stable. Why Is Cyclohexane Special? Although cyclohexane forms a ring, it avoids angle strain (unlike smaller rings) by adopting non-planar conformations. The ideal bond angle (109.5°) is maintained through specific 3D shapes, … Read more

Conformational Isomerism in n-Butane (C₄H₁₀) Conformational Isomerism in n-Butane (C₄H₁₀) arises from C–C bond rotation, giving anti, gauche, and eclipsed forms with different stabilities. Rotation around the C₂–C₃ Bond n-Butane has a straight chain: CH₃–CH₂–CH₂–CH₃. Rotation about the C₂–C₃ bond generates multiple conformations. Key Conformations Anti Conformation (Staggered): The two methyl groups are 180° apart. … Read more

Conformational Isomerism in Ethane (C₂H₆) Conformational Isomerism in Ethane (C₂H₆) shows staggered and eclipsed forms from C–C bond rotation, with staggered being more stable. Structure and Rotation Ethane contains a C–C sigma bond that allows free rotation. Each carbon is bonded to three hydrogen atoms. The rotation around the C–C bond leads to different conformations. … Read more

Nomenclature of Geometrical Isomers is done using cis-trans or E-Z system, based on the relative positions or priority of substituents. Nomenclature of Geometrical Isomers There are three main systems used to name geometrical isomers: Cis-Trans Nomenclature When it is used: Simple alkenes or cycloalkanes with identical groups Basis of naming: Relative positioning of identical groups … Read more

E–Z Nomenclature System uses Cahn–Ingold–Prelog rules to name isomers based on priority groups around a double bond (E = opposite, Z = same side). Why Use E-Z Nomenclature System? When each carbon in the double bond has two different substituents, the cis-trans system is not sufficient. In such cases, the E-Z system provides a consistent … Read more

Cis-Trans Nomenclature names geometrical isomers by positioning similar groups on the same side (cis) or opposite sides (trans) of a double bond or ring. When to Use: Use the Cis-Trans system when each carbon in the double bond has one identical group. It is suitable for: Simple alkenes with symmetrical groups, Cycloalkanes, where two substituents … Read more

Syn-Anti System (Syn-Anti Nomenclature) describes stereoisomers by the relative positions of substituents on adjacent atoms or double bonds. Applicability: This system is less commonly used for simple alkenes and more common in: Cyclic compounds Organic reaction mechanisms (especially eliminations and additions) Carbohydrate and organometallic chemistry Rules and Definitions of Syn-Anti System Syn: Two groups (atoms … Read more

Methods of Determination of Configuration of Geometrical Isomers involve techniques to identify cis-trans or E-Z arrangements in molecules. Methods of Determination of Configuration of Geometrical Isomers Geometrical isomerism (cis-trans or E-Z isomerism) occurs in compounds with restricted rotation (such as double bonds or cyclic structures), leading to different spatial arrangements of groups around the bond … Read more