Chapter 2 Flashcards
(24 cards)
Conformational isomers
Differ in rotation around a single bond
What are the types of conformational isomers
Staggered, anti staggered, gauche, eclipsed, total eclipsed
Staggered conformation
groups 60 degrees apart
Anti-staggered conformation
two large groups are 180 degrees apart
gauche conformation
two large groups are 60 degrees apart
eclipsed
two large groups are in front of each other
total eclipsed is directly in front of each other
Angle strain
created by stretching or compressing angles from normal size
torsional strain
from eclipsing conformations
non bonded strain
interactions between substituents on non adjacent carbons
**sterics
Axial vs equatorial
axial is up or down from plane
equatorial is in plane (STABLE)
Configurational enantiomers
can only be interchanged by breaking and reforming bonds
enantiomers
non superimposable mirror images. Opposite stereochemistry at every chiral carbon
Same chemical and physical properties, rotate plane polarized light differently
Optical activity
ability to rotate plane polarized light
D= positive, rotate to right
L= negative, rotate to left
Racemic mix
equal concentration of two enantiomers. Not optically active, they cancel each other out
meso compounds
have an internal plane of symmetry. Are optically inactive (two side cancel each other out)
have chiral centers
Diastereomers
non mirror image stereoisomers
Differ at some but not all chiral centers
Different chemical and physical properties
Cis/trans isomers
diastereomers that have different position at immovable bond (double bond)
Chiral center
4 different groups attached to central carbon
relative configuration
gives stereochemistry in relation to another molecule
absolute configuration
gives stereochemistry
uses Cahn Ingold priority rules
Cahn Ingold rules
higher atomic number has higher priority.
Z vs. E alkene
Highest priority on same side=Z
R vs S configuration
Lowest priority in back, draw circle
Clockwise=R
Counterclockwise=S
Fischer diagram
vertical lines go into page, dash
horizontal lines come out, wedge
Switching or rotating 90 will invert stereochemistry
