Oxygen-Containing Compounds

Question 1

Physical properties of alcohols

Answer 1

• Hydrogen bonding.
• Higher boiling point than the same compound without the alcohol group.
• Water soluble as long as molecule does not contain a long hydrophobic region.

Question 2

S_N1 reaction with alcohols

Question 3

S_N2 reaction with alcohols

Question 4

What factors favor S_N1?

Answer 4

stable carbocation, tertiary carbon center, protic solvent.

Question 5

What factors favor S_N2?

Answer 5

unstable carbocation, primary carbon center, aprotic (but polar) solvent.

Question 6

Describe the strength of the following oxidizing agents: KMnO₄, CrO₃, and PCC?

Answer 6

• KMnO₄ and CrO₃ will oxidize primary alcohols to carboxylic acids
• PCC (Pyridine Chlorochromate) and other weak oxidizing agents will only oxidize a primary alcohol to the aldehyde.

Question 7

Secondary alcohols will always oxidize to what:

Answer 7

Ketones

Question 8

Mechanism of Pinacol Rearrangement

Answer 8

A strong acid (H2SO4) protonates and then rearrangement occurs.

Question 9

Protection of alcohol groups

Answer 9

Best protection group is trimseyl silyl:

• To protect, add Cl-SiMe3 to R-OH.
• The alcohol gets “capped” into R-O-SiMe3.
• To deprotect, add F-.

Question 10

Reactions with SOCl₂ and PBr₃

Answer 10

R-OH + SOCl₂ –> R-Cl (by products: SO₂ + HCl)

R-OH + PBr₃ –> R-Br (by products: H₃PO₃, R₃PO₃, HBr)

Question 11

Preparation of mesylates, tosylates, and tosylates:

Question 12

Purpose of preparing mesylates, tosylates, and triflates

Answer 12

They are great leaving groups for nucleophilic substitution

Question 13

Esterification of alcohol

Question 14

What is an inorganic ester?

Answer 14

replace the carbon of esters with a different atoms

Question 15

Formation of inorganic ester using PBr₃

Question 16

Formation of an inorganic ester using SOCl₂

Question 17

Why are inorganic esters important for biochemistry?

Answer 17

In biochemistry DNA/RNA polymerization, the 3’-OH alcohol group attacks the 5’-phosphate to form an inorganic ester linkage (phosphodiester linkage of DNA/RNA backbone).

Question 18

Hydrogen bonding of alcohols results in:

Answer 18

hydrogen bonding in alcohols give them a higher boiling point than their corresponding alkanes.

Question 19

Effect of chain branching on physical properties of alcohols

Answer 19

going from straight chain to branched alkane (with same # carbons) = higher freezing/melting point, lower boiling point.

Question 20

Physical properties of aldehydes and ketones

Answer 20

• C=O bond is polar, with the carbon partially positive and oxygen partially negative.
• Dipole-dipole interactions give these molecules higher boiling points than their corresponding alkanes, but not as high as the corresponding alcohols or carboxylic acids.

Question 21

Nucleophilic addition at the carbonyl bond to form a hemiacetal or acetal.

Question 22

Nucelophilic addition at the carbonyl to form an imine

Question 23

Nucleophilic addition at the carbonyl to form an enamine

Question 24

Halform reaction mechanism

Question 25

Aldol condensation mechanism

Answer 25


Question 26

Internal H-bonding in 1,3 di-carbonyls

Answer 26


Question 27

Keto-Enol Tautomerism (extra: which is more stable?)

Answer 27


Question 28

Formation of organometallic compounds and purpose of organometalic compounds

Answer 28

 Organometallic compounds makes R-, which attacks C=O to make R-C-OH. The purpose of organometallic compounds is to make carbon-carbon bonds.

Question 29

Wolff-Kishner Reaction

Answer 29


Question 30

Grignard Reagents for carbonyls

Answer 30

 Grignard reagents are just like organometallic reagents, they produce R-.

Question 31

Effect of substituents on reactivity of C=O

Answer 31

bulky groups on either side of C=O blocks access to the electrophilic carbon, so reactivity goes down.

Question 32

Why are alpha protons acidic?

Answer 32

Alpha proton is acidic because the resulting carbanion is stabilized by resonance.

Question 33

Physical properties and solubility of carboxylic acids

Answer 33

* High boiling point due to hydrogen bonding. * Soluble in water.

Question 34

Describe the general mechanism for a nucleophilic attack for a carboxylic attack.

Answer 34

Question 35

What is the product of LiAlH₄ and a carboxylic acid?

Answer 35

It creates a primary alcohol. Carboxylic acids can only be reduced by lithium aluminum hydride.

Question 36

Decarboxylation mechanism for beta-keto acids

Answer 36


Question 37

Reactants and mechanism for esterification

Answer 37

Carboxylic acid and R-OH in acidic conditions 

Question 38

Halogenation of Carboxylic Acids at the alpha position (four-step mechanism)

Answer 38


Question 39

General principles of carboxylic acids

Answer 39

* High boiling points due to hydrogen bonding * Dimerization due to hydrogen bonding * Weak acid

Question 40

Electron Withdrawing Groups Inductive Effect on Carboxylic Acids

Answer 40

electron withdrawing groups makes the acid stronger.

Question 41

Physical properties of carboxylic acid derivatives

Answer 41

* C=O bond is polar, so there are dipole-dipole interactions. * No hydrogen bond exists in acid chlorides, anhydrides, or esters unless there is an -OH group somewhere. * Amides can hydrogen bond because of the N-H group. In fact, hydrogen bonding involving the amide backbone of polypeptides form the secondary structure of proteins. * Amides have higher boiling points than the other acid derivatives. * Acid derivatives have high boiling points than alkanes because of the C=O dipole interactions.

Question 42

Synthesis of acyl chloride from carboxylic acid

Answer 42


Question 43

Reactions of acyl chloride

Answer 43


Question 44

Reactions of acid anhydrides

Answer 44


Question 45

Reactions of esters

Answer 45


Question 46

Amide to carboxylic acid

Answer 46


Question 47

Reaction of carboxylic acids to acid derivatives

Answer 47


Question 48

Nucleophilic substitution mechanism for carboxylic acids

Answer 48


Question 49

Hoffman Rearrangement

Answer 49


Question 50

Transesterification reaction

Answer 50


Question 51

Hydrolysis of fats and glycerides (saponification)

Answer 51


Question 52

Hydrolysis of amides

Answer 52


Question 53

Relative reactivity of acid derivatives

Answer 53


Question 54

Steric Effects on Carboxylic Acid Derivatives

Answer 54

bulky groups around the C=O group helps protect the carbon center from nucleophilic attack.

Question 55

Strain of amides (beta-lactam)

Answer 55

Amides have a double bond characteristic between the carbon and nitrogen. This means that the C-N bond can not rotate. An example is beta-lactam, which is a four-membered ring with 1 amide in it.