Chapter 5

Question 1

The study of three dimensional structures of molecules

Answer 1

Stereochemistry

Question 2

Have the same bonding sequence, but they differ in the orientation of their atoms in space

Answer 2

Stereoisomers

Think of left and right hand

Question 3

Objects that have left-handed and right handed forms are called…
Objects that have a plane of symmetry are called…

Answer 3

Chiral

Achiral

Question 4

If carbon has four different groups then it is…..

If carbon has two of the same groups…

Answer 4

Chiral

Achiral

Question 5

An object is ___________ if there are three dimensional shapes are equivalent.

Answer 5

Superimposable

-some molecules have mirror images that are non-superimposable

Question 6

A _______ compound always has a non-superimposable mirror image.

Such non-superimposable mirror image molecules are called __________.

Answer 6

Chiral

Enantiomers

Question 7

A carbon atom that is bonded to four different groups is called a _________.

Answer 7

Chiral carbon atom

Question 8

If a compound has no chiral carbon atom it is usually…

Answer 8

Achiral

Question 9

If a compound has just one Cairo carbon atom, it is _______.

Answer 9

Chiral

Question 10

If a compound has more than one chiral carbon….

Answer 10

It may or may not be Chiral

-most of the time it will be Chiral?

Question 11

True or false?

Any molecule that has internal mirror plane of symmetry cannot be chiral, even though it may contain chiral carbon atoms

Answer 11

True

Question 12

The most widely excepted system for naming the configuration of chiral carbon atoms is the \_\_\_\_\_\_\_\_\_\_\_, which is signs to each chiral carbon atom 
 a letter (R) or (S)

Answer 12

Cohn-Ingold-Prelog convention

Question 13

Atoms with ______ atomic numbers receive higher priorities.

In the case of ties, use the next atoms along the chain as tiebreakers

Treat double and triple bonds as if…

Answer 13

Higher

Each were a bond to a separate atom

Question 14

Stereoisomers that are not enantiomers are….

Answer 14

Diastereomers

Question 15

If one is R and one is S, must be….

Answer 15

Enantiomers

Question 16

What happens if you change any two groups on a chiral Carbon?

Answer 16

Then you get the enantiomer (opposite handedness or mirror image)

Question 17

Clockwise is _____,

Counter clockwise is _______.

Answer 17

R, S

Question 18

Where do you put the fourth priority group?

Answer 18

In the back

Question 19

________ molecules have nearly identical physical properties.

Ex: boiling point, melting point, and reference index is the same

What is different?

Answer 19

Mirror image

Their optical rotations are different

Question 20

When a molecule is connected the same (same groups), but is oriented different.

Answer 20

Stereoisomers

Question 21

Before the relationship between chirality and optical activity was known, enantiomers were called __________, because they were distinguish by their optical activity

Answer 21

Optical isomers

Question 22

A ________ measures the rotation of polarized light

Answer 22

Polarimeter

A sodium lamp is typically employed producing what is called the sodium D line.

Question 23

Compounds that rotate the plane of polarized light towards the right are called…

Towards the left…

Answer 23

Dextrorotatory (+)

Levorotatory. (-)

Question 24

A mixture that has an optical rotation of equal magnitude in opposite directions, the net optical rotation is zero. A solution of equal amounts of two enantiomers, so the mixture is optically inactive is called…

Answer 24

A racemic mixture
AKA Racemic modification

• many reactions lead to racemic products, especially when and an achiral molecule is converted to a Chiral molecule

Question 25

A reaction that uses optically inactive reactants and catalyst cannot produce a product that is optically active. Any chiral product must be formed as a…

Answer 25

Racemic mixture

Question 26

Sometimes we deal with mixtures that are neither optimally pure(all one enantiomer) nor racemic (equal amounts of two enantiomers). In these cases, we specify the ___________ of the mixture. The enantiomer excess is a similar method for expressing the relative amounts of enantiomers in a mixture

Answer 26

Optical purity

Question 27

A molecule cannot be optically active if it’s chiral conformations are in equilibrium with its __________.

Answer 27

Mirror images. * to determine whether a conformational mobile molecule can be optically active, consider its symmetric conformation.

Question 28

Fisher projections facilitate comparison of__________.

Answer 28

Stereoisomers

Question 29

In working problems with Fisher projections, you may have noticed that by rotating 180° the configuration….. A 90° rotation causes…

Answer 29

Remains the same The vertical bonds to go horizontal and the horizontal bonds to go vertical leading to a false representation of the actual structure

Question 30

What happens when you do a double swap?

Answer 30

Get you back to R

Question 31

Enantiomers is a __________ between two molecules

Answer 31

Comparison

Question 32

Achiral compound with Chiral centers

Answer 32

meso compound (d,l pair)

Question 33

Isomers whose atoms are bonded together in the same order but differ in how the atoms are directed in space All other isomers are classified as what?

Answer 33

Stereoisomers Diastereomers

Question 34

How do you figure out how many stereoisomers are possible?

Answer 34

2^n. (n is The number of chiral centers)

Question 35

Stereoisomers that are not mirror images

Answer 35

Diastereomers

Question 36

_____________ are isomers whose atoms are bonded together in the same order but differ in how the atoms are directed in space

Answer 36

Stereoisomers

Question 37

compounds that are achiral even though they have Chiral carbons atoms are called…. They have a _______ plain of symmetry

Answer 37

Meso compounds Mirror 

Question 38

What are the two types of isomers?

Answer 38

Constitutional isomers (structural isomers) and stereoisomers (same connectivity but different spacial arrangement)

Question 39

The two types of stereoisomers

Answer 39

Diastereomers and enantiomers (mirror image) 

Question 40

Two types of diastereomers 

Answer 40

Cis/trans and other diastereomers (two or more chirality centers)