Ochem Exam 3

Front 1

Enantiomers

Back 1

Stereoisomers that are non superimposable mirror images

Front 2

Diastereomers

Back 2

Stereoisomers that are NOT mirror images of each other

Front 3

How many different groups are needed for a central Carbon atom to be considered Chiral?

Back 3

4

Front 4

How is a Chiral and Achiral central carbon different?

Back 4

A Chiral has 4 different moleclules attached to the central C while the Achiral central C has a plain of semitry

Front 5

How many chiral carbons are needed on a molecule to make the molecule chiral?

Back 5

Just one

Front 6

Define Optical Activity

Back 6

It is that organic molecules rotate plane polarized light.

Front 7

Enantiomers have atleast 2 forms.
1 rotates light (-) _____ ______
2 rotates light (+)_____ ______

Back 7

(-) left - Levorotatory
(+) right - Dextrotatory

Front 8

Do Achiral molecules rotate light?

Back 8

No

Front 9

Do Chiral molecules rotate light?

Back 9

Yes

Front 10

Who discovered Enantiomers?

Back 10

Louis Pasteur

Front 11

In IUPAC naming,
R =?
S =?

Back 11

Clockwise
Counter clockwise

Front 12

In IUPAC naming you take the lowest priority attached atom to the central C and point it?

Back 12

Away from you

Front 13

If you have a molecule with one chiral center it will have?

Back 13

enantiomers (mirror images)

Front 14

If you have a molecule with more than one chiral center you will have?

Back 14

A possiblity of diastereomers (non mirror images)

Front 15

The Threonine isomer that is naturally occuring and is an amino acid for our bodies is the ____isomer

Back 15

2S,3R

Front 16

Three things needed to be chiral?

Back 16

Central C atome with 4 different attached molecules
No plane of Semitry
Tetrahedral

Front 17

2R,3R -->2R,3S =

Back 17

Diastereomers

Front 18

2S,3S --> 2R,3S =

Back 18

Diastereomer

Front 19

2R,3R --> 2S,3S =

Back 19

Enatiomer

Front 20

2R,3S --> 2S,3R =

Back 20

Enatiomer

Front 21

You can tell if the molecule has a MESO form if it has _____?

Back 21

A plane of symetry.

Front 22

If the molecule is MESO does it have Optical activity?

Back 22

No

Front 23

If the molecule is MESO is it chiral?

Back 23

No, its the same molecule?

Front 24

What is a Racemic Mixture?

Back 24

A mixture of 50:50 R,S enantiomers

Front 25

How do you prepare a Alkyl Halide?

Back 25

you make them from alcohols

Front 26

When making Alkyl Halides, which has best reactivity: tertiary, secondary, primary, or methyl.

Back 26

tertiary, Because SN1 rxn happens under neutral or acidic conditions and favors tertiary (Fast for SN1)

Front 27

Primary and secondary alcohols work best with what molecules?

Back 27

PBr3 and SOCl2

Front 28

When making Alkyl Halides from tertiary alcohols, what should you use?

Back 28

HX

Front 29

What is a Grignard Reaction?

Back 29

They are a carbon metal bond.
R-Mg-X = a magnesium halide
(-)(+)

Front 30

What do they mean when they say an organometallic compound?

Back 30

It means the metal is in the middle.

Front 31

In Gringnard Reactions, what halide can NOT be used?

Back 31

F

Front 32

In Gringnard Reactions, what halides can be used?

Back 32

Cl, Br, and I

Front 33

In nucleophilic Substitutions Reactions, Alkyl Halides are generally electrophiles or nucleophiles?

Back 33

electrophiles.

Front 34

If the Alkyl Halides are electrophilic, they either do 1 of 2 things, what are they?

Back 34

1. substitution of X
2. elimination of HX (which equals an alkene so done't forget the double bond)

Front 35

In substitution, the X is _______ by the OH-?

Back 35

Replaced, X is the leaving group and leaves a + charge that the OH- take.

Front 36

In elimination, the X is ________ by the OH-?

Back 36

eliminated, the X leaves and the OH- takes an H, makes H2O and the alkene is formed.

Front 37

Nucleophilis Substitution Rxn occurs by 2 pathway:

Back 37

1. SN1
2. SN2

Front 38

In SN reactions a nucleophile (Nu:-) reacts w/ a __________ and substitutes for a leaving group.

Back 38

substrate (R-X), the X is replaces into (R-Nu)

Front 39

In SN rxns, when Nu: is (-) the product is?

Back 39

Neutral

Front 40

In SN rxns, when Nu: has no charge the product is?

Back 40

Positive

Front 41

When MAKING an alkyl halide:
1. Tertiary alcohols use what chemical for transformation?
2. Secondary & Primary use what chemical for transformation?

Back 41

1. H-X
2. SOCl2 or PBr3

Front 42

The SN2 reaction takes place in how many steps?

Back 42

One step w/o an intermediate

Front 43

In an SN2 reaction the NU: attacks where?

Back 43

the back 180 from the X or LG

Front 44

SN2 reactions the rate is determined by?

Back 44

The concentration of the substrate (alkyl haildie) and the nucleophile

Front 45

In an SN2 rxn, when the NU: attacks from the back it changes the molecules?

Back 45

configuration
From an S to an R or vice versa

Front 46

Common LG for an SN2 rxn are?

Back 46

I-, Br-, Cl-

Front 47

SN1 Reactions take place in what type of C substrate?

Back 47

tertiary

Front 48

SN1 Reactions work in what type of environment?

Back 48

Neutral or acidic

Front 49

in an SN1 reaction is there an intermediate?

Back 49

yes

Front 50

How many steps in an SN1 reaction

Back 50

2 steps

Front 51

In an SN1 reaction how does the leaving group leave?

Back 51

spontaniously

Front 52

In an SN2 reaction how does the leaving group leave?

Back 52

as the Nu attacks the substrate, the LG group gets pushed off. This happens all at the same time that is why there is no intermediate.

Front 53

The rate of an SN1 reaction depends on the?

Back 53

Concentration of the substrate only

Front 54

in an SN1 reaction, the Nu: can attack from where? and what does this make?

Back 54

either side, because the LG is gone.
a racemic mixture 50:50

Front 55

What are the LG groups in an SN1 reaction?

Back 55

Same as SN2, Cl-, I-, Br-

Front 56

Elimination reactions almost always give mixtures of _______ products.

Back 56

alkene

Front 57

Alexander Zaitsev's Rule?

Back 57

The more highly substituated will be more prevelent in solution.

Front 58

E1, the C-X bond?
How many steps?

Back 58

Spontaniously breaks like in the SN1 (C is partially +)
2 steps (there is an intermediate)

Front 59

E2, the C-X bond is?
How many steps?

Back 59

based induced for bond cleavage like the SN2 (C is partially -)
1 step (no intermediate)

Front 60

E1cB, the C-X bond is?
How many steps?

Back 60

Base abstraction of the proton occurs 1st.
2 steps (there is an intermediate)

Front 61

Don't forget, all E reactions give rise to ______?

Back 61

double bonds.

Front 62

Primary alkyl halide substitution use?

Back 62

SN2

Front 63

Primary alkyl halide eilmination (w/ OH) use?
If 2 carbons away from the carbonyl group use?

Back 63

E2
E1cB

Front 64

Secondary alkyl halide substitution use?

Back 64

SN2

Front 65

Terteriary alkyl halide:
Basic use?
Neutral use?
Acidic use?
Basic 2 away use?

Back 65

E2
SN1 (substitution) E1 (elimination)
E1cB

Front 66

Synthesis of an alcohol from a carbonyl cmpd is done by oxidation or reduction?

Back 66

reduction

Front 67

Synthesis of Alcohols:
Reduction of Aldehydes (R-C=O) gives __________ and uses ______ to do it.

Back 67

Primary alcohols
NaBH4

Front 68

Synthesis of Alcohols:
Reduction of Ketones (R-C-R, C=O) gives__________ and uses ______ to do it.

Back 68

Secondary alcohols.
NaBH4

Front 69

Synthesis of Alcohols:
Reduction of Carboxylic Acid (R-C-OH, C is =O) gives __________ and uses ______ to do it.

Back 69

primary alcohols
LiAlH4

Front 70

Synthesis of Alcohols:
Reduction of Esters (R-C-OR, C=O) gives __________ and uses ______ to do it.

Back 70

primary alcohols
LiAlH4

Front 71

Synthesis of Alcohols:
Formaldehyde (H2C=O) w/ a Gringnard (RMgX) gives what type of alcohol?

Back 71

Primary

Front 72

Synthesis of Alcohols:
Aldehydes (RC=O) w/ a Gringnard (RMgX) gives what type of alcohol?

Back 72

Secondary

Front 73

Synthesis of Alcohols:
Ketones (RC=O,C) w/ a Gringnard (RMgX) gives what type of alcohol?

Back 73

Teritary

Front 74

Synthesis of Alcohols:
In reduction of a carboxylic acid or ester, you add what?

Back 74

LiAlH4 - 2 H's, one in the OH (comes from [H] and one because we got rid of the double bond from H3O+.

Front 75

Synthesis of Alcohols:
in the gringnard reagent what part is the LG?

Back 75

MgX, the R stays and attaches to the new molecule.

Front 76

Reactions of Alcohols:
The dehydration of Alcohols is the?

Back 76

elimination of H2O to give an alkene.

Front 77

Reactions of Alcohols:
In Dehydration of OH, the H adds to what in the first step?

Back 77

it adds to the OH making H2O

Front 78

Reactions of Alcohols:
In Dehydration of OH, the second step H2O?

Back 78

is the LG and removes it's self leaving a positive charge behind

Front 79

Reactions of Alcohols:
In Dehydration of OH, the third step the the H2O?

Back 79

Takes an H from the molecule.

Front 80

Reactions of Alcohols:
In Dehydration of OH, the forth step, the H is now missing and what forms?

Back 80

a double bond.

Front 81

Reactions of Alcohols:
Oxidation of alcohols are the turning of what to what?

Back 81

Alcohols to carbonyl compds.

Front 82

Reactions of Alcohols:
Oxidation: Primary alcohols turn into?

Back 82

Carboxylic acid

Front 83

Reactions of Alcohols:
Oxidation: Secondary alcohols turn into?

Back 83

Ketones

Front 84

Reactions of Alcohols:
Oxidation: Tertiary alcohols turn into?

Back 84

No Rxn

Front 85

Reactions of Alcohols:
What are the 3 Oxidation reagents?

Back 85

Na2Cr2O7
CrO3
Periodinane (expensive)

Front 86

Reactions of Alcohols:
Conversion into Ethers steps
1.
2.

Back 86

1. add Alkali metal or strong base NaH
2. add alkyl halide (Williamson ether synthesis)

Front 87

Reactions of Alcohols:
Ethers: The best reactivity comes from what type of alkyl halides?

Back 87

Primary, the more hindered the substrates the more E2 will occur.

Front 88

Reactions of Alcohols:
Ethers: the CH3 that comes from the CH3-X is bonded to?

Back 88

The O.

Front 89

Reactions of Ethers:
can only under go one general reaction, what is it?

Back 89

CLEAVED by a strong acid. HI or HBr.
you should have 2 molecules in the end.

Front 90

Reactions of Ethers:
SN2 pathway to do list:
1
2

Back 90

1. check for O to be attached to primary or secondary carbons. NOT Tert.
2. the X goes with the less hindered group

Front 91

Reactions of Ethers:
SN1 pathway to do list:
1
2

Back 91

1. Check for O to be attached to a tert carbon.
2. X goes with tert group

Front 92

Cyclic Ethers: Epoxides (triangle with an O)
Epoxides into Alcohols: how easily can they be cleaved?

Back 92

Very easily, they are unstable due to strain.

Front 93

Cyclic Ethers: Epoxides
how are epoxides cleaved?

Back 93

by an acid, base, grignard (RMgX), Nu:

Front 94

Cyclic Ethers:Epoxides
Cleaved by HX what happens

Back 94

OH in the opening and the X opposite side for trans stereochemistry

Front 95

Cyclic Ethers:Epoxides
Cleaved by H3O+ what happens

Back 95

OH in the opening and another OH in the trans position.

Front 96

The Nature of Carbonyl Cmpds:
List the 2 groups of carbonyl compounds based on the chemistry they undergo:

Back 96

1. Aldahydes and Ketones
2. Carboxylic Acids and derivites

Front 97

The Nature of Carbonyl Cmpds:
Why are carboxylic acids better leaving groups than Aldehydes and ketones?

Back 97

They are able to stabilize a negative charge.

Front 98

Oxidation of Aldehydes:
What is the most common agent to convert aldehydes into carboxylic acids?

Back 98

CrO3

Front 99

What do you get?
Aldehyde (NaBH4)-->

Back 99

Alcohol
C-C-OH

Front 100

What do you get?
Ketone (NaBH4)-->

Back 100

Prop-2-al
C-OH-C all single bonds, C bonded to an O which is bonded to the H and the C making an alcohol

Front 101

What do you get?
Aldehyde (RMgX/H3O+)-->

Back 101

an secondary alcohol
OH
C-C-H
C

Front 102

Nucleophilic Addition Reactions:
The alkoxide ion is protonated by?

Back 102

H-A

Front 103

Nucleophilic Addition Reactions:
What is the alkoxide ion

Back 103

it is the intermediate under Basic conditions

Front 104

Nucleophilic Add of Hydride and Grignard Reagents: Alcohol formation
Aldehydes with NaBH4 make a?
Ketones with NaBH4 makes a?

Back 104

primary alcohol
secondary alcohol

Front 105

Synthesis of Alcohols from Carbonyl cmpds:
Reduction of Aldehydes and Ketones:
NaBH4 and what solvent is used?

Back 105

H3O+

Front 106

Nucleophilic Additon of Hydride & Grgnard Rxn: Alcohol Formation
Addition of Hydride (H-) Reagent: Reduction
NaBH4 and what solvent is used?

Back 106

Ethanol H-O-R