5th

Question 1

enantiomer similarities

Answer 1

same chemical properties

Question 2

which chemical properties do enantiomers share

Answer 2

melting point
boiling point
solubility
IR + NMR spectra

Question 3

enantiomer differences

Answer 3

rotate plane polarised light differently
interact diff in biological systems (one a good drug one a bad drug)

Question 4

enantiomers and plane polarised light

Answer 4

enantiomer pairs can rotate plane polarised light by the same amount but in opposite directions

Question 5

enantiomer that rotates light to the left is called

Answer 5

L -

LEVO ROTATORY

Question 6

enantiomer that rotates light to the right

Answer 6

D +

DEXTRO ROTATORY

Question 7

how many chiral centres can there be

Answer 7

many!!

Question 8

more chiral centres means there’s more

Answer 8

R + S combinations

Question 9

if there’s 2 chiral centres the combos are

Answer 9

RR
SS
RS
SR

Question 10

RR will be the mirror image of

Answer 10

SS
they are enantiomers!!
behave as if they only have one chiral carbon

Question 11

RR will not be the mirror image of

Answer 11

RS

Question 12

RR AND RS WILL BE CALLED

Answer 12

DIASTEREO ISOMERS

dd diastereo 🎵 liv and maddie were not enantiomers as they weren’t mirror images of eachother 💋🏀

Question 13

diastereoisomers

Answer 13

non identical stereoisomers
not mirror images of eachother
may have chiral centres

Question 14

diastereoisomer pair properties

Answer 14

diff physical + chem properties
diff melting + boiling points
diff behaviour on silica
diff NMR + IR spectra

Question 15

how to find number of possible isomers based on amount of stereogenic centres

Answer 15

2^n

where n is number of chiral centres
this gives total number: ANS/2 to give u number of enantiomer pairs

Question 16

how does strain affect diastereomers

Answer 16

some cannot exist bc of the strain 🫣⛓️🫨🤬

Question 17

meso compound

Answer 17

has chiral centres
not chiral overall
(plane of symmetry??) if this is rotated, the molecules are the same!!

Question 18

how to catch a meso compound out

Answer 18

look for planes of symmetry
rotate the molecule (if 2 look the same it’s bc they are!!)

Question 19

what do allenes look like

Answer 19

XC=C=CX

Question 20

can allenes be chiral

Answer 20

yes girl ofccc!!
if the Carbons are bonded to different things then yes
both carbons can be bonded to the same 4 diff things

Question 21

we can also expect to see chirality whennn

Answer 21

planes are perpendicular
🫳🖐️

Question 22

stereoisomers can also form due to …

Answer 22

steric clashes!!
repulsion between certain groups can prevent C-C bond rotation forming stereoisomers
HAPPENS IN BIPHENYLS

Question 23

example of biphenyl that cannot rotate along its C-C bond due to steric clashes

Answer 23

BINAP

Question 24

what is a helice

Answer 24

non superimposable mirror images of eachother.
not identical
chiral
found in nature: dna, proteins
can go clockwise or anti-clockwise
hand example always stuck in ur head(thumbs touching and hands sliding past eachother)

Question 25

what does helice acc mean tho

Answer 25

multiple helixes!! 🧬

Question 26

racemic mixture // racemate

Answer 26

mixture of 50:50 (r + s) enantiomer ratio
will not rotate plane polarised light

Question 27

plane polarised light rotation can help us with what??

Answer 27

can help us figure out how much of one enantiomer there is in a mixture

figure out optical rotation of both enantiomers when pure first

Question 28

how can we separate enantiomer pairs

Answer 28

gas and liquid chromatography
use a chiral selector that reacts different with diff enantiomers in the stationary phase. they will form diastereoisomers which have different
affinities to the stationary phase and allow for them to be separated

Question 29

how else can we measure the relative amounts of enantiomers

Answer 29

separate enantiomers by forming diastereomers
these will have different physical properties 🧊 + 🔥 points
these can be used to identify the relative amounts of enantiomers

Question 30

all methods used to assess relative amounts of each enantiomer usually

Answer 30

either permanently or temporarily turn the enantiomers into diastereoisomers.

Question 31

process of separating one enantiomer from a racemic mixture

Answer 31

chiral resolution

Question 32

enantiomers have the same H NMR spectra so how can we tell the difference between them

Answer 32

• covalently react them with moshers acid chloride to form diastereoisomers which have different H NMR spectra.
• introduce chelating ligands (chiral shift reagents) which bind differently to diff enantiomers + form diastereoisomer complexes. these will have different characteristics in spectroscopy etc.

Question 33

how else can we separate enantiomers

Answer 33

crystallisation

amine enantiomere + chiral acid -> diastereoisomeric salts

these have diff solubilities
different pH will allow the pure amine enantiomers to be released.