Chapter 4

Question 1

Stereoisomers

Answer 1

Same connectivity to the same carbon, different spatial arrangements. If you swap any 2 atoms it becomes a different mo,molecules

Conformational isomers (cannot be separated, rotation around single bon)

Configuration all isomers can be separated (geometric (cis/trans, EZ) or optical (R-S))

All chiral centres are stereocenters

Question 2

Geometric isomers

Answer 2

Cis, same side, trans, opposite sides (not super imposable)

Cis and trans result fro. Restricted rotation

1. Cyclic structures restrict rotation
   2.double bonds restrict rotation

Question 3

E Z

Answer 3

E: différent, low and high priority opposite

Z: same, low and high priority same side

Priority depends on atomic mass

Question 4

Énantiomorphes

Answer 4

One chiral center with that can exist as 2 different optical isomers

Are different compounds, but have the same physical and chemical properties

(Same melting point but opposite specific rotation)

Question 5

Achiral

Answer 5

Plane of symmetry present

Can even have a chiral center, but can still be achiral molecule

Alkenes are always achiral

Question 6

Chiral center

Answer 6

Swap any 2 atoms and it becomes a mirror image (enantiomer)

4 different molecules connected to carbon

Question 7

Plane polarized light

Answer 7

Light all at a certain plane (ex all vertical) after it passes through a polarizer

When chiral compound is in plane polarizer, light rotates, if rotates ckockwise it’s + and counterclockwise -, if molecule S=+ then automatically R=-, and inversely

Question 8

Factors that affect a (alpha)

Answer 8

Alpha is angle of rotation of light

Path legit of the light I’m the solution (length of tube, l) directly related in dm

Concentration of solution (c) directly related in ??

Temperature (not predictable)

Wavelengths of light (unpredictable)

a=constantlc

Chiral molecules also affects it, incorporated in constant, so constant unique for every chiral molecule

Constant called specific rotation = [a]

Question 9

Racemic mixtures

Answer 9

Equal amount of the left handed and right handed chiral molecules

Angle of rotational is 0 (cancels each other out)

Is called optically inactive (can also be a solution of achiral nolecules)

Higher melting point than pure solution but same solubility

Question 10

Enantiomeric excess

Answer 10

=(observed specific rotation)/(specific rotation of pure enantiomers)* 100

Percentage of opposite chiral compound will that much of the majoritarian present chiral compound and that’s what will be left (90%S 10%R =80% S)

Question 11

Number of stereoisomers by chiral centres

Answer 11

2^n maximum

Question 12

Enantiomers

Answer 12

Mirror images, what was R is now S

Have opposite signs of same specific rotation value

Question 13

Diastereomers

Answer 13

Not same but not mirror images (different physical properties)

Question 14

Meso compound

Answer 14

2 or more chiral center, but achiral, has a plane of symmetry

Chiral center at top (R) is the opposite to the other one (S)

Optically inactive