Stereoisomerism and Chirality Flashcards Preview

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Flashcards in Stereoisomerism and Chirality Deck (56)
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1
Q

What is the study of molecules as three-dimensional objects?

A

Stereochemistry

2
Q

Define:

Mirror Image

A

The reflection of an object in a mirror

3
Q

Can your reflection be superposed (placed on top of) the original ‘you’ in such a way that every detail of the reflection corresponds exactly to the original?

A

No.

You and your reflection are different objects. You cannot exactly superpose one on the other

4
Q
# Define:
Chiral
A

Objects that are not superposable on their mirror image. (from the Greek, cheir, hand). An object that has “handedness”

5
Q

Define:

achiral

A

When an object and its mirror image are superposable. It lacks chirality.

6
Q

What is a plane of symmetry?

A

An imaginary plane passing through an object or a molecule dividing it such that one half is the reflection of the other half.

7
Q

What is a center of symmetry?

A

A point so situated that identical components of the object or molecule are located equidistant and on opposite sides from the point along any axis passing through that point.

8
Q

True of False:

Because it has a center of symmetry, cyclobutane is identical to its mirror image and is achiral.

A

True

9
Q

An object that lacks both a center of symmetry and a plan of symmetry are ____?

  1. Achiral
  2. Chiral
A

Chiral

10
Q

How are stereoisomers different than constitutional isomers?

A

Constitutional isomers have the same molecular formula but a different connectivity of atoms in their molecules.

Stereoisomers have the same molecular formula and the same connectivity but with different orientations of their atoms in space

11
Q

define:

Stereoisomer

A

Stereoisomers have the same molecular formula and the same connectivity but with different orientations of their atoms in space

12
Q

Define:

Configurational Isomers

A

Configurational Isomers are isomers that differ by the configuration of substituents on an atom

13
Q

Are these molecules constitutional isomers or configurational isomers?

A

Configurational isomers

14
Q

What is the most specific term to describe the central carbon in this molecule?

  1. enantiomer
  2. chiral center
  3. stereocenter
  4. diasteriomer
A

Chiral center

a tetrahedral atom, most commonly carbon, bonded to four different groups. It lacks the two key symmetry elements and is chiral.

15
Q

What is the difference between chiral/achiral and enantiomer?

A

Chiral and achiral refer to objects, while the term enantiomer refers to the relationship between a pair of objects

16
Q

This is the definition for what concept?

A carbon atom with four different groups bonded to it

A

Chiral center

17
Q

which definition is more broad?

Chiral center or Stereocenter

A

Stereocenter

18
Q

Define:

Stereocenter

A

A stereocenter is an atom about which exchange of two groups produces a stereoisomer

19
Q

Define:

enantiomer

A
20
Q

When isomers are chiral, are they enantiomers or diastereomers?

A

Enantiomers

21
Q

Define:

diastereomers

A
22
Q

How many different groups is the central carbon bonded to?

A

4

Cl, CH3, CH2CH3, and H

23
Q

Are these enantiomers of each other?

A

Yes

24
Q

What is the difference between configurational isomers and conformational isomers?

A

Configurational isomers require the breaking of bonds while conformational isomers occur through rotations along single bonds

25
Q

Enantiomers or diastereomers?

A

Diastereomers, because they are not mirror images of each other

26
Q

Enantiomers or Diastereomers?

A

Enantiomers. They are mirror images and not superposable

27
Q

Does this molecule have a chiral center? Is the molecule chiral?

A

This molecule does not have a chiral center, but it is chiral. It is an atropisomer

28
Q

Define atropisomer

A
29
Q

Define absolute configuration

A
30
Q

What is the R,S System?

A
31
Q

What is the 1st priority rule in the R,S System of naming chiral centers?

A
32
Q

What is the 2nd priority rule in the R,S System of naming chiral centers?

A
33
Q

What is the 3rd priority rule in the R,S System of naming chiral centers?

A
34
Q

What is the 4th priority rule in the R,S System of naming chiral centers?

A
35
Q

Assign priorities to the groups

A
36
Q

Assign priorities to the groups

A
37
Q

How do you assign R or S configuration to a chiral center?

A
38
Q

Is the chiral center R or S?

A

S

39
Q

Is the chiral center R or S?

A

R

40
Q

Is the chiral center R or S?

A

R

41
Q

True or false

More double bonds lead to more possible stereoisomers

A

True

42
Q

How many stereoisomers are possible in a molecule with 3 chiral centers?

A
  1. we use the rule of 2n = # of stereocenters

in this case, 23 = 8

43
Q

What is the formula to determine stereocenters from the number of chiral centers?

A

2n

44
Q

Name this molecule

A

2,3,4-Trihydroxybutanal

45
Q

How many stereoisomers are possible for this molecule?

A

It contains 2 chiral centers. 22 = 4

this molecule can have 4 stereocenters

46
Q

Name this molecule

A

3-chloro-2-butanol

47
Q

How many stereoisomers are there in 2,3-Dihydroxybutanedioic acid (Tartaric acid)?

A
  1. One meso compound and one pair of enantiomers.
48
Q

Define Meso compound

A

A mesa compound contains two or more chiral centers but is achiral. To be a meso compound, a molecule must also have chiral isomers

49
Q

What are three examples of achiral solvent environments?

A

H2O, CH3CH2OH, CH2Cl2

50
Q

Define Fischer projection

A
51
Q

How can you quickly tell if there is an enantiomer of a molecule with only one chiral center?

A
52
Q

How can you quickly tell if there is an enantiomer of a molecule with more than one chiral center?

A
53
Q

How can you quickly recognize a diastereomer?

A
54
Q

Define optically active

A
55
Q

Define resolution

A
56
Q
A