Isomers Flashcards Preview

Chemistry GRE > Isomers > Flashcards

Flashcards in Isomers Deck (21)
Loading flashcards...
1
Q

Three classes

A

Constitutional, conformational, stereoisomers

2
Q

Constitutional isomers

A

Structural isomers that differ in the positions of their constituent atoms

3
Q

Conformational isomers

A

Isomers that arise from different orientations around a sigma bond, which may rotate relative to one another

4
Q

Conformational isomers

A

Either eclipsed or staggered

Eclipsed > staggered, in terms of energy

5
Q

Conformational isomers

A

The relative populations of conformational isomers are temperature dependent

6
Q

Cyclo- conformational isomers

Stability

A

Chair>twist>boat

7
Q

Stereoisomers

A

Differ in their spatial, 3-D arrangements

8
Q

Geometrical isomers

A

When rotation about a bond or bonds is not possible due to a ring system of pi bond

9
Q

Enantiomers

A

Nonsuperimposable, chiral mirror images

10
Q

Diastereomers

A

Stereoisomers that are not Mirror images of each other

Geometrical isomers are diastereomers

11
Q

Enantiomers

A

Have identical physical and chemical properties; they are not easy to separate

12
Q

Diastereomers

A

Have different physical and chemical properties; they are easy to separate by conventional means

13
Q

Racemic mixture

A

50-50 mixture of a pair of enantiomers

14
Q

R and S convention

A

R equals right, S equals left

15
Q

R and S convention naming steps

A
  1. ) assign priorities based on mass
  2. ) visualize with lowest priority pointing away from you
  3. ) rotate going 1,2,3
16
Q

Meso molecules

A

Have chiral centers but are not chiral overall

Mirror image is identical in every way, have internal mirror plane

17
Q

Optical activity meso

A

Optically inactive

18
Q

Optical activity racemic

A

Optically inactive

19
Q

Optical activity enantiomers

A

Optically active but flip in opposite direction

20
Q

Optical rotation

A

Plane polarized light is a group of photons that are all moving in the same direction AND have electromagnetic fields oscillating in the same place

21
Q

Optical activity chiral centers

A

Optically active and rotate plane polarized light