Sterochemistry Quiz Flashcard

Physiochemical properties effected by stereochemistry

solubility

mp

bp

polarity

density

pka

Biological properties effected by stereochemistry

oral availability

protein binding

distribution

target activity

What is stereochemistry?

defines and describes the three dimensional spatial arrangement of atoms in a molecule

 

the study of isomers

What are isomers?
Compounds with the SAME molecular formula, but DIFFERENT constitutions, conformations, or configurations

Constitutional Isomers

 

 

 

other name?

Structural isomers:

 

differ in connectivity of atoms

Conformational Isomers

isomers at potential energy minima, identical in constitution/configuration. differ only in torsion angles

 

different functional groups rotate around C-C or C-heteroatom bonds

Configurational Isomers

 

 

other name?

Stereoisomers

 

isomers with same connectivity, differ in position of atoms in space

 

(has both internal reference and aspect of comparing 2 molecules)

When drawing constitutional isomers, avoid labile, reactive groups, including…

Enol ethers

Hemi-acetals

Carbonates

Cations and Anions

Torsion angle

 

(what is it and what type of isomer are we talking about?)

rotation around one bond in one molecule

 

Conformational isomers

Eclipsed,

 

Staggered:

              Anti, Gauche

energy (high to low):

 

Eclipsed(large group eclipsing other large group)

Gauche

Anti

Do alkyl groups favor equatorial or axial?
equatorial – more favored as size increases

 

 

Atropisomers

 

what are they and what kind of isomer

Conformational

 

steric strain locks the isomer into one of the two steroisomers (can’t rotate)

;

possess axial chirality

;

;

4 kinds of

Configurational Isomers

;

Geometric isomers – cis/trans

enantiomers

diastereomers

meso compounds

;

;

Geometric Isomers

;

differ in position of ligand relative to a reference plain

;

cis, trans

applies to: alkenes, cycloalkanes

;

If an alkene has more than 2 substituents, what nomeclature do we use?

Not cis/trans!

E/Z!

E: high priority on opp. sides

Z: high priority on same side

E like trans, Z like cis

;

;

;

What is an enantiomer?

;

Stereoisomer not superimposable on it’s mirror image

 

 

What is a racemic mixture?

(racemate)

 

 

a 1:1 mixture of two enantiomers

 

 

What atoms can a stereocenter occur around?

 

Carbon

Sulfur

Phosphate

 

 

Counter clockwise?

 

 

 

S

 

 

Clockwise?

 

 

R

 

 

Diastereomer

 

Non super imposable

NON mirror image

 

ex. E/Z olefins; more than 1 stereocenter

 

If all centers are flipped (all that were R become S, all that were S become R) what type of stereoisomer do you have?

 

 

Enantiomer

(if one is not flipped: diastereomer)

Get instant access to
all materials

Become a Member