Organic II Test 3

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1

Compounds containing carbonyl groups undergo what two types of reactions?

1. Nucleophilic addition

2. Nucleophilic substitution

2

Which is more reactive, aldehydes or ketones?

Aldehydes

3

The first step of nucleophilic addition is:

Nucleophilic attack

4

The second step of nucleophilic addition is:

Protonation

5

The first step of nucleophilic substitution is:

Nucleophilic attack

6

The second step of nucleophilic substitution is:

Loss of leaving group

7

Most useful agents for reducing aldehydes and ketones

1. Sodium borohydride (NaBH)

2. Lithium aluminum hydride (LiAlH)

3. Polar metal H-bond

8

Reduction reactions start with ___ C-O bond(s) and end with ___ C-O bond(s).

2, 1

9

A ketone reacting with NaBH4 or CH3OH yields -->

Allylic alcohol

10

A ketone reacting with H2 in the presence of excess Pd-C yields -->

Ketone

11

A ketone reacting with H2 yields -->

Alcohol

12

Redox reactions of carbonyl compounds yields a __:__ mixture.

50:50

13

Treatment of a ketone or aldehyde with a halogen (X) and either acid or base results in substitution of __ for __ on a alpha-C.

H, X

14

Example of a chiral reducing agent:

*used in the presence of H2O

(R)-CBS or (S)-CBS

15

(R)-CBS yields -->

(S)-CBS yields -->

(S) = minor

(R) = major

16

A biological reducing agent is:

NADH

17

Mild reducing agents:

1. DIBAL-H

2. LiAl[OC(CH3)3]3

18

Acid halides and esters convert to either _________ or _________, depending on the reagent.

aldehyde, 1-degree alcohol (Ex. RCH2OH)

19

LiAlH4 reduces carboxylic acids to:

1-degree alcohols

20

LiAlH4 reduces amides to:

amines

21

Reagents used for oxidation of aldehydes:

1. CrO3

2. Na2Cr3O7

3. K2Cr2O7

4. KMnO4

22

General structure of organometallic reagent:

C bonded to a metal (R-M)

23

Most common metals used in organometallic reagents:

Li, Mg, Cu

24

The more polar the metal, the ____ reactive the reagent.

reactive

25

Organometallic reagents are _____ bases that readily abstract a proton from water to form hydrocarbons.

strong

26

Aldehydes and ketones form ________ in the presence of organometallic reagents.

alcohols

27

Carboxylic acid derivatives form ________ or ________ in the presence of organometallic reagents.

ketones or alcohols

28

Other functional groups form ________ or _________in the presence of organometallic reagents.

Carboxylic acids or alcohols

29

3 step strategy for protecting groups:

1. Convert OH into another functional group that does not interfere

2. Carry out reaction

3. Remove protecting group

30

Common OH protecting group:

Silyl ether

31

Organocuprates are _____ reactive organometallics.

less

32

General structure for organocuprate:

R2CuLi

33

Grignard reagents react with CO2 to produce:

Carboxylic acids

34

Preparation of aldehydes involves oxidation of a ___________ with __________.

1-degree alcohol, PCC

35

Cyclohexone reacting with NaBH4/LiAlH4 in the presence of H2O yields -->

Alcohol

36

Cyclohexone reacting with RMgX/RLi in the presence of H2O yields -->

Alcohol

37

Cyclohexone reacting with -CN in the presence of HCl yields -->

Cyanohydrin

38

Cyclohexone reacting with Ph3P+--CR2 yields --> oxaphosphetene which reacts with -Ph2P=O to yield -->

Alkene

39

Cyclohexone reacting with RNH2 (1-degree amine) in the presence of a mild acid yields --> carbinolamine, which in the presence of H2O yields -->

Imine

40

Cyclohexone reacting with R2NH (2-degree amine) in the presence of a mild acid yields --> cabinolamine, which in the presence of H2O yields -->

Enamine

41

Cyclohexone reacting with ROH, H+ yields --> hemiacetal -->

Acetal

42

An alkene reacts with O3 in the presence of Zn/H2O or CH3SCH3 to yield _________ and _________.

Ketone, aldehyde

43

Witting reactions use C nucleophiles for form __________.

alkenes

44

In a witting reaction, the carbonyl group is converted to a _____________.

C=C bond

45

The two resonance structures of the Witting reagent are:

Ph3P+--CH2, Ph3P=CH2

46

Treatment of an aldehyde or ketone with a 1-degree amine yields -->

imine

47

Imines are classified as 1-, 2-, or 3-degree based on the number of ______ groups bonded to the N atom

alkyl

48

An imine has a bond angle of:

120 degrees

49

Imines form fastest when reaction medium is weakly _______.

acidic

50

Treatment of an aldehyde or ketone with a 2-degree amine yields -->

enamine

51

General structure of enamine:

R-NR2

52

General structure of imine:

R=NR

53

Imines and enamines can be converted back to carbonyl compounds by reacting with _____.

H3O+

54

Treatment of carbonyl compounds with H2O in the presence of acid or base catalysts adds H and OH across the C-O pi bond to form a __________.

gem-diol

55

Aldehydes and ketones react with 2 equivalents of alcohol in the presence of H+ to form:

acetals

56

General structure of acetal:

OR"

|

R -- C -- R'

|

OR"

57

Aldehydes and ketones react with 1 equivalent of alcohol in the presence of H+ to form:

hemiacetals

58

General structure of hemiacetals:

OR

|

>C-OH

59

Reacting a ketone with a vicinal diol (OH on different Cs) yields -->

cyclic acetal

60

Three types of anhydrides:

1. Symmetrical (both R groups identical)

2. Unsymmetrical (R groups different)

3. Cyclic (R groups are two points on cyclic compound)

61

To name an acyclic acid chloride, change suffix -ic acid of parent carboxylic acid to suffix ___ __________.

-Ex. Acetic acid -->

-yl chloride

--> Acetyl chloride

62

To name an anhydride, change suffix acid to _________.

-Ex. Acetic acid -->

anhydride

--> Acetic anhydride

63

To name an ester, follow these steps:

1. Name R' group bonded to O atom as an alkyl group

2. Name acyl group (RCOO-) by changing the -ic acid of parent carboxylic acid to -ate

64

To name a 1-degree amine, replace the suffix with _______.

-Ex. Acetic acid -->

amide

--> Acetamide

65

Anhydride + H2O -->

Carboxylic acid

66

Anhydride + R'OH (alcohol) -->

Ester

67

Anhydride + 2 NH3 -->

1-degree amide

68

RCOOH (carboxylic acid) + SOCl2 -->

RCOCl (acyl chloride) + SO2 + HCl

69

The reaction of a carboxylic acid (RCOOH) and an alcohol (ROH) in the presence of H2SO4 is called _______ ___________.

Fischer esterfication

70

R-COOH + R-OH + H2 SO4 -->

R-COOR + H2O

71

DCC (dicyclohexylcarbodimine) is a(n) __________ agent.

dehydrating

72

Structure of DCC:

Ph-N=C=N-Ph

73

When ester is hydrolized with water in the presence of acid, it yields -->

Carboxylic acid

74

When ester is hydrolized with water in the presence of base, it yields -->

Carboxylate anion

75

Esters react with NH3 and amines to form:

1-, 2-, and 3- amines

76

Amides are the _____ reactive derivatives.

least

77

Amides in the presence of acid yield-->

Carboxylic acid and ammonium (by-product)

78

Amides in the presence of a base yield -->

Ester anion and neutral amine (by-product)

79

General structure of a nitrile:

R-C=-N

80

Nitriles are prepared by the SN2 reaction of:

unhindered methyl and 1-degree alkyl halides with -CN

81

Hydrolysis of nitriles in the presence of acid yields -->

Carboxylic acids

82

Hydrolysis of nitriles in the presence of a base yields -->

Carboxylate anions

83

Reduction of a nitrile with LiAlH4 yields -->

1-degree amine

84

Reduction of a nitrile with DIBAL-H yields -->

Aldehyde

85

Reduction of a nitrile with an organometallic reagent yields -->

Ketone

86

Reactions at the C alpha to the carbonyl group proceed by way of ________ and __________.

enols, enolates

87

General structure of an enol:

R-C(OH)=CH 2

88

General structure of an enolate:

R-C(=O)--CH 2

89

In keto-enol tautomerization, equilibrium favors _________.

Ketones

90

In 1,3-dicarbonyl compounds, equilibrium favors __________.

Enols

91

pKa value of C-C:

50

92

pKa value of CH2=CHCH3:

43

93

pKa value of (CH3)2C=O:

19.2

94

pKa value of CH3-CH2-OH:

16

95

pKa of CH3-CO2-H:

4.8

96

pKa of amide:

30

97

pKa of nitrile:

25

98

pKa of ester:

25

99

pKa of ketone:

19.2

100

pKa of aldehyde:

17

101

pKa of 1,3-diester:

13.3

102

pKa of 1,3-dinitrile:

11

103

pKa of B-keto ester:

10.7

104

pKa of B-diketone:

9

105

pka of H2O:

15.7

106

LDA quickly ________________ all carbonyl starting materials.

deprotonates

107

pKa of diisopropylamine:

40

108

For unsymmetrical carbonyls, two enolate paths are possible:

1. 2-degree removal

2. 3-degree removal

109

For unsymmetrical carbonyls, the removal of the __-degree H is faster.

2

110

For unsymmetrical carbonyls, the removal of the __-degree H is more stable.

3

111

Removal of the 2-degree H in unsymmetrical carbonyls is a ________ process.

kinetic

112

Removal of the 3-degree H in unsymmetrical carbonyls is a _________ process.

thermodynamic

113

3 conditions favoring kinetic enolates:

1. Strong nucleophilic base (LDA) --> ensures enolate forms rapidly

2. Polar aprotic solvent (THF) --> dissolves starting materials

3. Low temperatures --> -78 C

114

3 conditions favoring thermodynamic enolates:

1. Strong base

- Na+ -OCH2CH3

- K+ -OC(CH3)2

2. Polar protic solvent (CH3CH2OH)

3. Room temperature

115

Treatment of a ketone of aldehyde with a halogen (X) and either acid or base results in substitution of __ for __ on a alpha-C.

H, X

116

Treatment of a ketone or aldehyde with a halogen (X) in the presence of acid requires two steps:

1. tautomerization of the carbonyl compound to the enol form

2. reaction of enol with halogen

117

Treatment of a ketone or aldehyde with a halogen (X) in the presence of a base is _____ useful.

less

118

When a ketone or aldehyde is treated with X2 in the presence of an acid -->

one alpha-H is replaced with X

119

When a ketone or aldehyde is treated with X2 in the presence of a base -->

both alpha-H are replaced with X

120

Methyl ketone + X2 (excess) + -OH -->

Carboxylate anion + CHX3 (haloform)

121

General structure of haloform:

CHX3

122

Treatment of an aldehyde or ketone with a base and alkyl halide results in ____________.

alkylation

123

Four steps of malonic ester synthesis:

1. Form enolate

2. SN2 reaction

3. Hydrolysis of ester

4. Remove CO2

124

Malonic ester synthesis converts diethyl malonate to __________ ______.

carboxylic acid

125

Four steps of acetoacetic ester synthesis:

1. Deprotonation

2. Alkylation

3. Hydrolysis

4. Decarboxylation

126

Two molecules of an aldehyde or ketone react with each other in the presence of a(n) _______ to form a B-hydroxy carbonyl compound.

base