cap. 3 Flashcards
chapters 5 and 6 (19 cards)
chiral
when the mirror image of the object is different from the original image
achiral
an object that can be superimposed (original and mirror image are the same)
enantiomers
compounds that are nonsuperimposable images. if a molecule is chiral, it will have an enantiomer
when is a carbon atom chiral?
when it is bonded to 4 different groups. it will produce an enantiomer.
any molecule that has a plane of symmetry will be
achiral
R and S priorities
- atoms with higher atomic numbers will have higher priorities. isotopes with the higher number will take priority.
- the atoms assigned priorities must be directly attached to the center C. if everything is the same, then you can move onto the next adjacent atom to assign priority.
- ## double and triple bonds will be treated like another bond (a double bond to O would mean 2 bonds to O)
R is in the direction of
clockwise
S in the direction of
counterclockwise
properties of enantiomers
same bp, mp, and density. same refractive index.
what will be different of enantiomers?
the plane of polarised light will be the same magnitude, but in opposite directions.
levoratory
negative degrees. it is counterclockwise pointing to 0 (NOT related to R and S)
dextrarotatory
positive degrees, clockwise pointing to 0 (NOT related to R and S).
racemic mixture
equal densities of d and l enantiomers. no optical activity.
when will racemic mixtures form?
when optically inactive reagents combine to form a chiral molecule
if equilibrium exists between 2 chiral conformers, then
the molecule is not chiral
fischer projection rules
- highest oxidized carbon is at the top. the least oxidized will be on the bottom
- rotation of 90 degrees is not allowed (creates enantiomers)
diastereomers
molecules with 2+ chiral carbons
stereoisomers that are not mirror images
meso compounds
compounds that have a plane of symmetry
if the molecule were rotated, it can be superimposed on the other image
overall it will be achiral even if it has chiral atoms
