Organic Chemistry: Conformations
Terms
Anti
-
A staggered conformation where two large groups are placed in their most
stable positions at a dihedral angle of 180 degrees. Also refers generally
to any geometrically arrangement of groups in opposing positions.
Conformation
-
Different 3-dimensional shapes that can be taken by a molecule by rotating
about single bonds.
Dihedral angle
-
Angle formed between two bonds on neighboring atoms in a Newman projection.
Eclipsed
-
A conformation where bonds have dihedral angles of zero degrees. This
typically maximizes the energy.
Gauche
-
A staggered conformation where large groups at a dihedral angle of 60
degrees repel each other.
Newman projection
-
A depiction of the conformation of a molecule where it is viewed down the atoms of a particular bond.
Staggered
-
A conformation where bonds have dihedral angles of sixty degrees. This
typically minimizes the energy.
Steric hindrance
-
Repulsion between the electron clouds on bulky groups of a molecule or
between molecules.
Syn
-
Steric hindrance between terminal methyl groups in a system of at least
five carbon centers. Also a generic term describing groups oriented in the
same direction; i.e. the opposite of anti.
Torsional strain
-
Resistance to rotation about a single bond caused by steric hindrance of
eclipsing interactions.
Torsional energy
-
The energy it takes to overcome torsional strain, or the difference in
energy between eclipsed and staggered conformations.
