Alicyclic Chemistry Flashcards

Vocabulary flashcards for reviewing alicyclic chemistry, covering cycloalkanes, nomenclature, physical properties, isomerism, ring strain, and conformations.

Alicyclic Chemistry

Chemistry of ring-shaped compounds.

Cycloalkanes (Alicyclic Compounds)

Cyclic alkanes with carbon atoms arranged in a ring.

CnH2n

General formula for cycloalkanes.

Cyclo-

Prefix added to the alkane name to name simple cycloalkanes.

Number of Carbons

The number of vertices in a regular polygon representing a cycloalkane.

Base Name Determination

Determines the base name in cycloalkane nomenclature; consider cyclic vs. acyclic portion carbon count.

Carbon Numbering

Numbering rule for cycloalkanes to give the lowest numbers for substituted carbons.

Boiling and Melting Points

Physical property that increases with increasing molecular mass in cycloalkanes.

Rigid Structure

Structural feature of cycloalkanes that leads to greater attractive interactions.

Higher Density

Physical property related to the rigid structure of cycloalkanes, allowing molecules to pack more effectively.

Geometric Isomers (Cis and Trans)

Isomers that arise in cycloalkanes because of restricted rotation about C-C bonds.

Cis Isomer

Isomer where two non-hydrogen substituents are on the same side of the ring.

Trans Isomer

Isomer where two non-hydrogen substituents are on the opposite sides of the ring.

Angle Strain (Baeyer Strain)

Difference between a tetrahedral angle and the internal angle of a polygon, used as a stability measure.

Tetrahedral Angle (109.5°)

Ideal angle between any pair of bonds when carbon is bonded to four other atoms.

Angle Strain (Bayer Strain)

Strain arising when bond angles in cycloalkanes deviate from 109.5°.

Angle Strain

Distortion of bond angles from the most stable angle.

Torsional/Bond Strain

Eclipsing of bonds on neighboring atoms causing strain.

Steric Strain

Repulsive interactions between non-bonded atoms in close proximity.

Ring Strain

Combination of angle and torsional strains in cycloalkanes.

Heats of Combustion

Method used to calculate ring strain.

Cyclopropane

Most strained cycloalkane due to angle and torsional strain.

Puckered Conformation

Conformation adopted by cyclobutane to reduce torsional strain.

'Envelope' Conformation

Term describing the puckered conformation of cyclopentane that reduces torsional strain.

Cyclohexane

Most common cycloalkane, existing in chair and boat conformations.

Chair Conformation

Most stable conformation for cyclohexane with all bond angles at 109.5° and no eclipsing interactions.

Boat Conformation

Conformation of cyclohexane with bond angles of 109.5° but with torsional strain due to flagpole hydrogens.

Twist Boat Conformation

Conformation adopted by the boat conformation to avoid unfavorable interactions.

Axial Bonds

Positions in cyclohexane pointing straight up and down.

Equatorial Bonds

Positions in cyclohexane pointing out from the ring.

Ring-Flip

Process by which chair conformations interconvert, exchanging axial and equatorial positions.

Gauche interaction (1,3 diaxial interaction)

Interaction that leads to added energy when a methyl group is in the axial position of a cyclohexane ring.