Isomers

Question 1

Structural/Constitutional Isomer

Answer 1

Same molecular formula, different structure

Question 2

Stereoisomers

Answer 2

Same molecular formula & same connectivity

Question 3

Conformational Stereoisomers

Answer 3

Same molecular formula & connectivity & do not require breaking bond to interconvert (rotation around a sigma bond)

Question 4

Configurational Stereoisomers

Answer 4

Same molecular formula & connectivity & do require breaking bond to interconvert

Question 5

Enantiomer

Answer 5

A configurational stereoisomer (same structure& requires breaking) and they are nonsuperimposable mirror images

Question 6

Diastereomer

Answer 6

A configuartional stereoisomer that doesnt have a nonsuperimposable mirror image

Question 7

Which kind of isomer used cis/trans configuration

Answer 7

Diastereomer

Question 8

Cis

Answer 8

Diastereomers with functional groups on the same side of the bond

Question 9

Trans

Answer 9

Diastereomers with functional groups on opposite sides of the bond

Question 10

Physical properties

Answer 10

Melting point, boiling point, solubility, odor, color, and density

Question 11

Chemical properties

Answer 11

Reactivity of molecule, change in composition of molecule attributed to functional groups

Question 12

Newman projection

Answer 12

Configuration down a sigma C-C bond

Question 13

Staggered confirmation

Answer 13

No overlap between atoms along line of sight

Question 14

Anti confirmation

Answer 14

Two largest groups are are antiperiplanar to each other

-most energetically favorable

Question 15

Gauche confirmation

Answer 15

Staggered confirmation with two largest groups 60 degrees from each other (right next to each other)

Question 16

Antiperiplanar

Answer 16

Same plane but on opposite sides

Question 17

Eclipsed confirmation

Answer 17

All groups are directly aligned and the largest functional groups are 120 degrees apart

Question 18

Totally eclipsed

Answer 18

The highest functional groups are -directly ontop of each other- highest energy state- synperiplanar

Question 19

Synperiplanar

Answer 19

Two groups on the same plane, on the same side

Question 20

What is the interconversion barrier between anti and totally eclipsed butane

Answer 20

19 kcal/mol (very low)

Question 21

Factors that cause ring strain:

Answer 21

Angle strain, torsional strain,nonbonded strain/steric strain (van der Waals repulsion)

Question 22

Angle strain

Answer 22

When bond angles deviate from their ideal values by beings stretched or compressed

Question 23

Torsional strain

Answer 23

When cyclic molecules must assume eclipsed or gauche conformations

Question 24

Nonbonded/steric/van der Waals strain

Answer 24

nonadjacent atoms compete for the same space

Question 25

Flagpole interactions

Answer 25

groups that come in direct contact with each other and cause change of group rotation

Question 26

Axial

Answer 26

Groups that stick up or down perpendicular to the plane of the ring

Question 27

Equatorial

Answer 27

Groups that stick out parallel to the ring

Question 28

What happens during a chair flip?

Answer 28

All axial become equitorial and vice versa | Wedges and dashes still stay the same

Question 29

Bulkiest functional groups favor which position?

Answer 29

Equitorial position

Question 30

Configuration isomers

Answer 30

Only change by breaking & reforming bonds | Enantiomers & diastereomers -optic isomers

Question 31

Carbon atom with only 3 different substituents is ?

Answer 31

Achiral

Question 32

Different properties of enantiomers:

Answer 32

Different rotation of plane polarized light | React differently in chiral environments

Question 33

Rotation of plane polarized light right

Answer 33

clockwise, dextrorotary (+)

Question 34

Rotation of plane polarized light left

Answer 34

counter-clockwise, levorotatory (-)

Question 35

Direction of plane polarized light is:

Answer 35

Not related to absolute configuation of molecule | Not related to D & L or R & S

Question 36

Equation for specific rotation

Answer 36

a=a(obs)/c x l a= specific rotation c=concentration (g/mL) l= path length (dm)

Question 37

Racemic mixture

Answer 37

Both (+) and (-) enantiomers are present, no optical activity because both cancel each other out

Question 38

How to separate racemic mixtures

Answer 38

React with an enantiomer of another compound to form two diastereomers- can be separated out (+) enantiomer with (+,-) enantiomers (++) & (+-)

Question 39

Number of possible stereoisomers

Answer 39

2^n | n= chiral centers

Question 40

Cis-trans isomers

Answer 40

Geometric isomers that differ in position around an immovable bond

Question 41

Meso compound

Answer 41

A molecule with chiral center that has an internal plane of symmetry - either within the molecule or within the chiral center molecular equivalent of a racemic mixture

Question 42

E & Z forms

Answer 42

Relative configuration Z= zame side E= eppiste sides

Question 43

Relative configuration

Answer 43

E & Z nomenclature for compounds with polyunsubsistuited double bonds

Question 44

Rule of arranging molecules

Answer 44

Anytime two groups are switched on a chiral carbon,the stereochemistry is inverted

Question 45

R configuration

Answer 45

Clockwise

Question 46

S configuration

Answer 46

Counter-clockwise

Question 47

Determining configuration from Fischer projection (if lowest- priority is pointing to side/out of page)

Answer 47

Name all groups skipping over 4 & just skip over it | True designation is opposite

Question 48

An cis-trans isomer is a subtype of

Answer 48

diastereomer

Question 49

A meso compound

Answer 49

does not have an enantiomer