Conformational Terms Flashcards
(25 cards)
anti
description given to two substituents attached to adjacent atoms when their bonds are at 180 with respect to each other
eclipsed
a high energy conformation where the bonds on adjacent atoms are aligned with each other
staggered
a low energy conformation where the bonds on adjacent atoms bisect each other, maximizing the separation
gauche
description given to two substituents attached to adjacent atoms when their bonds are at 60degrees with respect to each other
syn
description given to two substituents attached to adjacent atoms when their bonds are at 0degrees with respect to each other
conformations
different spatial arrangements that a molecule can adopt due to rotation about sigma bonds
conformers
contracted version of conformational isomers
rotamers
alternative expression for conformational isomers
conformational isomers
structures that can be interconverted by rotation about sigma bonds
cycloalkane
an ring containing only C-C bonds
heteroatom
a non-carbon atom such as O, N, S, etc
heterocycle
a cyclic molecule that includes a heteroatom such as O, N, S, etc. as part of the ring
puckered
refers to the non-planar geometry of a cyclic structure
ring flipping
the process by which a ring changes it’s conformation
axial
a position on a cycloalkane in which the bond to the ring is perpendicular to the average plane of the ring (i.e. pointing towards the poles). Most commonly encountered in the chair conformation of cyclohexane
equatorial
a position on a cycloalkane in which the bond to the ring is approximately in the average plane of the ring (i.e. around the equator) Most commonly encountered in the chair conformation of cyclohexane
chair
the most stable conformation for cyclohexane
boat
a high energy conformation of cyclohexane that occurs during ring flipping
strain
energy associated with a system due to its geometry
angle strain
destabilization due to distortion of a bond angle from its optimum value caused by the electrostatic repulsion of the electrons in the bonds
Van der Waals strain
destabilization due to the repulsion between the electron clouds of atoms or groups. Also known as Van der Waals repulsion. This occurs when atoms or groups are too close to each other due to the electrostatic repulsion of the electrons
steric strain
a composite of the other strains (angle, torsional, Van der Waals) within a molecule
torsional strain
destabilization due to the repulsion between pairs of bonds caused by the electrostatic repulsion of the electrons in the bonds
torsional angle
angle between C-X and C-Y bonds in a X-C-C-Y system when viewed along the C-C bond. Rotation about the C-C bond will change this torsional angle, also known as a dihedral angle
