isomerism Flashcards
what are constitutional isomers?
Same molecular formula but different connectivity.
e.g. 2-methylpentane and 3-methylpentane \
both are C5H14
What are conformational isomers?
two compounds that differ by rotation around a sigma bond which are shown in Newman projections
what are stereoisomers?
isomers in which two compounds have the same formula and connectivity but differ in the spatial arrangement of the atoms
what is a chiral carbon aka stereocenter?
a carbon with 4 different substituents therefore cannot superimpose its mirror image on itself.
how many possible stereoisomers are there for a molecule of n stereocenters?
2^n is the max but not necessarily the amount
true or false, in a Fischer projections the vertical molecules are going into the page and the horizontal are coming out of the page.
true, it looks like a bow tie
what are enantiomers?
non-super imposable mirror images. these molecules have the opposite R/S stereochemistry at every carbon.
t or f, enantiomers only differ by optical activity
true
counterclockwise rotation - L - (-)
+ / - says nothing about R and S
what are diastereomers?
stereoisomers that are not enantiomers. At least one stereocenter will be the same.
a molecule that is RRR is what to a molecule that is
SSS or RSS?
SSS - enantiomers
RSS - diastereomers
t or f, molecules that are superimposable are identical?
true or they are meso compoounds
what are epimers?
a special type of diastereomers in which a single stereocenter is inverted and the rest are the same.
what are anomers?
epimers that exist at the anomeric carbon of a sugar.
the anomeric carbon is the carbon next to the sugars ether group.
in a sugar, if the OH group at the anomeric carbon is pointing down is it alpha or beta?
alpha
what is a meso compound?
when there is an internal plane of symmetry within a compound that contains stereocenters
