Organic Chemistry Ch2

Question 1

Structural Isomer

Answer 1

Share their molecular formula (same molecular weight)
- Different chemical and physical properties

Question 2

Physical properties

Answer 2

Characteristics of processes that don’t change the composition of matter

Question 3

Chemical properties

Answer 3

Relates to reactivity of the molecule with other molecules and results in changes in chemical composition

Question 4

Stereoisomers

Answer 4

• Same chemical formula, atomic connectivity
• Differ in how these atoms are arranged in space

Question 5

Conformational Isomers

Answer 5

Differ in rotation around single bonds

Question 6

Configurational Isomers

Answer 6

Can be interconverted only by breaking bonds

Question 7

Types of straight-chain Conformations

Answer 7

Staggered: no overlap of atoms along line of sight
Anti: two largest groups are antiperiplanar
Gauche: the two largest groups are 60 degrees apart
Eclipsed: two groups are 120 dergees apart
Totally eclipsed: Directly overlap, highest-energy state

Question 8

What three factors cause ring strain

Answer 8

Angle strain, torsional strain, nonbonded strain

Question 9

Angle strain

Answer 9

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

Question 10

Torsional Strain

Answer 10

When cyclic molecules must assume conformations that have eclipsed or gauche interactions

Question 11

Nonbonded stain

Answer 11

When nonadjacent atoms or groups compete form the same space

Question 12

Which cyclohexane conformation is the most stable

Answer 12

Chair conformation - minimizes all three types of strain

Question 13

Chair flip

Answer 13

One chair form is converted to the other
- briefly passes through fourth confirmation called half-chair
- all axial groups become equatorial and all equatorial groups become axial

Question 14

Chiral

Answer 14

If its mirror image cannot be superimposed on the original object - molecule lacks an internal plane of symmetry

Question 15

Achiral

Answer 15

Have mirror images that can be superimposed

Question 16

Enantiomers

Answer 16

Have the same connectivity but opposite configurations at every chiral center in the molecule - cannot be superimposed
- Identical physical and chemical properties with two notable exceptions: optical activity and reactions in chiral environments

Question 17

Optically activity

Answer 17

Refers to the rotation plane-polarized light by a chiral molecule
- A compound that rotates the plane of polarized light to the right (CW) is dextrorotatory (d-) and +
- A compound that rotates light left (CCW) is levorotatory (l-) and -

Question 18

Diastereomers

Answer 18

Non-mirror-image configurational isomers
- molecule has two or more stereogenic centers and differs at some but not all of these centers
- Similar chemical properties in some reactions due to same functional groups
- different physical properties

Question 19

Meso Compounds

Answer 19

Have chiral centers within it and an internal plane of symmetry