stereochemistry

Question 1

what is stereochemistry?

Answer 1

subdiscipline of chemistry that looks at the spacial arrangement of atom

Question 2

what is important in drug action?

Answer 2

3D structure is important in drug action

Question 3

what are isomers?

Answer 3

compounds have the same molecular formula

Question 4

types of isomers?

Answer 4

constitutional or structural isomers

Question 5

what are stereoisomers?

Answer 5

compounds that are the same but have a different arrangement of space

Question 6

what are confirmation isomers?

Answer 6

different conformations of the same molecule
interconvert easily through rotation around single bond

Question 7

what are configuration stereoisomers?

Answer 7

same groups are different in how they’re arranged around central carbon atoms
don’t interconvert easily so bond needs to be broken to interconvert

Question 8

what is strain?

Answer 8

when stable molecule have weaker bonds than acyclic c-c bond and more unstable than propane

Question 9

what are constitutional or structural isomers?

Answer 9

compounds with same molecular formula but different arrangement of atoms

Question 10

what are the two types of newman projections?

Answer 10

eclipsed conformer high energy
staggered conformer low energy

Question 11

what is the bond angle in angle strain?

Answer 11

60

Question 12

what is the structure of torsional strain?

Answer 12

‘planar molecule
can’t do bond rotation
hydrogens are eclipsed’

Question 13

structure of cyclobutane?

Answer 13

‘90 degrees angle
high ring strain
non-planar conformer minimizing eclipsing’

Question 14

structure of cyclopentane?

Answer 14

‘angle 180 degrees
non-planar minimizing eclipsing
little ring strain’

Question 15

structure of cyclohexane?

Answer 15

angle 109.5 degrees if non-planar
no ring strain
no eclipsing in chair conformation

Question 16

what are the hydrogens in cyclohexane arranged like?

Answer 16

either axial or equitorial

Question 17

how are axial and equatorial relationship changed?

Answer 17

via ring flip of conformer
the conformers energy stays the same

Question 18

how do you assign priority groups?

Answer 18

by looking at atomic number
(higher atomic mass for isotopes)

Question 19

structure of cyclohexane boats?

Answer 19

no ring strain
eclipsed in boat conformation
in twist-boat the flagpole and eclipsed interactions reduced
both boat and twist-boat are higher energy than chair

Question 20

what is tetrahedral carbon that can always be arranged in two ways called?

Answer 20

‘spatial sequence about a stereogenic centre’

Question 21

what are enantiomers?

Answer 21

‘two molecules with opposite configurations at all centres’

Question 22

what are R and S configurations?

Answer 22

R- clockwise rotation
S- anticlockwise

Question 23

what are diasterioisomer?

Answer 23

‘stereoisomers that aren’t an enantiomer’

Question 24

what are meso compounds?

Answer 24

groups around stereogenic centres that are symmetrical

Question 25

when is a meso compound optically inactive?

Answer 25

when there’s a plane of symmetry

Question 26

conformation vs configuration?

Answer 26

changing conformation doesn’t affect configuration

Question 27

what is the (+)- or dextrorotatory enantomer?

Answer 27

plane rotates clockwise
and isomer is active

Question 28

what is (–)- or laevorotatory enantiomer?

Answer 28

plane rotates anticlockwise
and isomer is inactive

Question 29

what is the equimolar mixture?

Answer 29

racemate or racemic mixture
where its optically inactive (±)-

Question 30

what are the physical properties of enantiomers and racemates?

Answer 30

between enantiomers the melting points are the same
racemates have different melting points
optical rotation is different in both
Pharmacological properties are different as well

Question 31

what is the equation for specific rotation?

Answer 31

observed rotation/concentration (g/ml)* path length (dm)