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Organic Chemistry: Carbocycles

Terms

Summary: Carbocycles

Introduction to Cycloalkanes

1,3-diaxial interactions  -  Steric hindrance between an axial substituent on a chair conformation and the hydrogens on ring positions three carbons away.
Angle strain  -  The formation of bent σ bonds in rings (3-, 4-membered) to accommodate unnatural ring angles.
A-value  -  Energetic cost of putting a substituent group in the axial position of a cyclohexane Chair as opposed to the equatorial position.
Axial  -  Bond positions on the cyclohexane chair parallel to the central rotation axis. These are typically drawn as vertical lines branching from the chair structure.
Bicyclic  -  A compound that contains two rings which share atoms with each other.
Bredt's Rule  -  No bridgehead alkenes. Bridgehead carbons are too constrained in the ring structures to incorporate double bonds.
Bridged  -  Joining of rings with more than two atoms. These shared atoms constitute a bridge.
Bridgehead carbons  -  Points at which rings meet in bridged polycyclic hydrocarbons.
Boat  -  Less stable conformation of cyclohexane; resembles a boat.
Chair  -  The most stable conformation of cyclohexane; resembles a lawn chair.
Chair flip  -  Interconversion between two chair conformations.
Equatorial  -  Bond positions on the cyclohexane chair that lie sideways toward the equatorial plane of the chair.
Flagpole hydrogen  -  Hydrogens at two ends of the cyclohexane boat conformation that repel each other due to steric hindrance.
Fused  -  The joining of rings that share two atoms and the bond between them.
Heat of Formation  -  The energy change that occurs when a molecule is assembled from its component atoms.
Polycyclic  -  Compound that contains several rings joined with common atoms.
Ring strain  -  Unfavorable energetics that arise from ring formation. These include both angle strain and torsional strain.
Spiro  -  Ring joining that shares a single atom, creating rings that lie in perpendicular planes.
Steric hindrance  -  Repulsion between the electron clouds on bulky groups of a molecule or between molecules.
Torsional strain  -  Resistance to rotation about a single bond caused by steric hindrance of eclipsing interactions.

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