Isomers

Question 1

Isomers

Answer 1

Same molecular formula only

Question 2

Constitutional (structural) isomers

Answer 2

Same molecular formula
diff connectivity

Question 3

Stereoisomers

Answer 3

Same molecular formula
Same connectivity

Question 4

Conformational isomers

Answer 4

same molecular formula
same connectivity
does not require bond breaking to interconvert

Question 5

Configurational isomers

Answer 5

same molecular formula
same connectivity
requires bond breaking to interconvert

Question 6

Diastereomers

Answer 6

same molecular formula
same connectivity
requires bond breaking to interconvert
superimposable
cis-trans

Question 7

Enantiomers

Answer 7

same molecular formula
same connectivity
requires bond breaking to interconvert
nonsuperimposable

Question 8

Anti staggered

Answer 8

Biggest groups 180° away
Least potential energy, most stable

Question 9

Gauche

Answer 9

Biggest groups 60° away
Second least potential energy
Second most stable

Question 10

Eclipsed

Answer 10

Biggest groups 120° away
Second most potential energy
Second least stable

Question 11

Totally eclipsed

Answer 11

Biggest groups back to back
Most potential energy
Least stable

Question 12

Most stable position for the bulkiest groups in cyclohexane conformation

Answer 12

Equatorial

Question 13

Chair flip

Answer 13

Equatorial becomes axial and axial become equatorial

But the groups that were up (wedge) remain up and the groups that were down (dashed) remain down

Question 14

Chirality

Answer 14

Mirror image cannot be superimposed
Lack an internal place of symmetry
4 diff groups on shared carbon

Question 15

Specific rotation

Answer 15

[α] = (α obs)/ (c x l)

α = degrees
c = g/mL
l = dm

Question 16

racemic mixture

Answer 16

when both (+) and (-) enantiomers are present in equal concentrations

No optical activity observed

Question 17

How many possible stereoisomers

Answer 17

2^n
n = # of chiral centers

Question 18

Meso compound

Answer 18

a molecule w chiral centers that has an internal plane of symmetry

no optical activity

Question 19

Fischer projection

Answer 19

• horizontal lines: bonds project out, wedges
• vertical lines: bonds going into plane, dashes