4th Flashcards
(22 cards)
constitutional isomer🌷
same empirical formula
atoms are connected differently
configurational isomerism🌷
cis/trans isomerism
not chiral
same empirical
same connectivity
not identical in 3d shape
can be called diastereomers
diastereomers
different chemical + physical properties
what leads to isomerism
restriction of rotation around the C=C bond
cis
same side
bucket looking
U
trans
different sides
stretched Z shape
E isomer
trans isomer
Z
cis isomer
priority of group is based on
atomic weight
heavier group gets priority
heaviest group on the same side
cis
z
heaviest group on opposite sides
trans
E
if groups directly bonded to the C are the same
keep moving down until they’re different
see which one has a higher atomic weight
double bonds are counted as
2 single bonds
C=O has priority over C-O
enantiomers🌷
different molecules as they cannot be overlayed
non superimposable mirror images of eachother
when do enantiomers occur most🌷
tetrahedral shape
(sp3 hybridised)
chiral Carbon
how to check similar enantiomers molecules are acc different molecules
rotate one around and see if it ‘forms’ the other one
chiral centre can also be called a
stereogenic centre
rules that help us name enantiomers
cahn ingold prelog rules
CIP
cahn inlog prelog rule steps
- assign a priority number 1=heaviest 4=lightest, normally H
- make sure number 4 is facing away from u
- draw an arrow from 1 to 2 to 3 etc
- clockwise = R, anti-clockwise = S
what if number 4 isn’t pointing away??
we must rotate the molecule so that 4 is dashed + pointing away from us.
keep the bonds in the same place and just move the atoms around to the next bond until 4 is on the dashed one.
if 4 isn’t pointing away or towards u, what do u do
invert the molecule so it’s pointing away
trick to save time when 4 is coming towards us
do the opposite answer // inverted answer
R->S
S->R
