Organic Chemistry Ch 6. Aldehydes and Ketones

Question 1

Aldehydes

Answer 1

Terminal functional groups containing a carbonyl bonded to at least one hydrogen, use the suffix -al and the prefix -oxo. In rings, they are indicated by the suffix -carbaldehyde

Question 2

Ketons

Answer 2

Internal functional groups containing a carbonyl bonded to two alkyl chains, use the suffix -one and the prefix oxo- or keto-

Question 3

Carbonyl

Answer 3

C=O, reactivity dictated by the polarity of the double bond, carbon has a partial positive charge and is therefore electrophilic

Question 4

Carbonyl containing compounds

Answer 4

Have higher boiling points than equivalent alkanes because of dipole interactions

Question 5

Alcohol containing compounds

Answer 5

Have higher boiling point than equivalent alkanes because of hydrogen bonding

Question 6

Aldehyde synthesis

Answer 6

Commonly produced by oxidation of primary alcohols, weaker, anhydrous oxidizing agents like pyridinium chlorochromate (PCC) must be used or the reaction will continue to a carboxylic acid

Question 7

Ketone synthesis

Answer 7

Commonly produced by oxidation of secondary alcohols, various oxidizing agents can be used such as dichromate, chromium trioxide, or PCC because ketones are the most oxidized functional group for secondary carbons

Question 8

Nucleophilic addition reactions

Answer 8

When a nucleophilic attacks and forms a bond with a carbonyl carbon, electrons in the pi bond are pushed to the oxygen atom, if there is no good leaving group (aldehydes and ketone), the carbonyl will remain open and is protonated to form an alcohol, if there is a good leaving group (carboxylic acid and derivatives), the carbonyl will reform and kick off the leaving group

Question 9

Hydration reactions

Answer 9

Water adds to a carbonyl, forming a geminal diol

Question 10

Hemiacetal formation

Answer 10

When one equivalent of alcohol reacts with an aldehyde via nucleophilic addition

Question 11

Hemiketal formation

Answer 11

When one equivalent of alcohol reactions with a ketone via nucleophilic addition

Question 12

Acetal formation

Answer 12

When another equivalent of alcohol reacts with a hemiacetal via nucleophilic substitution

Question 13

Ketal formation

Answer 13

When another equivalent of alcohol reactions with a hemiketal via nucleophilic substitution

Question 14

Imine, oxime, hydrazone, and semicarbazone formation

Answer 14

When nitrogen and nitrogen derivatives react with carbonyls

Question 15

Imine tautomerization

Answer 15

Imine enamines

Question 16

Enamines

Answer 16

Can tautomerize with imines

Question 17

Cyanohydrin formation

Answer 17

Hydrogen cyanide reacts with carbonyls

Question 18

Aldehyde oxidation

Answer 18

Aldehydes can be oxidized to carboxylic acids using oxidizing agents like KMnO4, CrO3, Ag2O, H2O2

Question 19

Aldehyde reduction

Answer 19

Can be reduced to primary alcohols using hydride reagents

Question 20

Hydride reagents

Answer 20

Reduction agents such as LiAlH4 or NaBH4

Question 21

Ketone oxidation

Answer 21

Cannot be further oxidized

Question 22

Ketone reduction

Answer 22

Can be reduced to secondary alcohols using hydride reagents

Question 23

Alpha carbon

Answer 23

The carbon adjacent to the carbonyl carbon, the electron withdrawing oxygen of the carbonyl weakens the CH bond on alpha carbons

Question 24

Alpha hydrogen

Answer 24

Hydrogens attached to the alpha carbon, relatively acidic and can be removed with a strong base, the electron withdrawing oxygen of the carbonyl weakens the CH bond on alpha carbons

Question 25

Enolate

Answer 25

Results from deprotonation of a enol and can be stabilized by resonance with the carbonyl, are good nucleophiles

Question 26

Ketones and nucleophiles

Answer 26

Less reactive because of steric hinderance and alpha carbanion destabilization, the presence of an additional alkyl group crowds the transition step and increases its energy, the alkyl group also donates electron density to the carbanion, making it less stable

Question 27

Keto from

Answer 27

C=0 form that aldehydes and ketone can exist in

Question 28

Enol form

Answer 28

double bond+hydroxyl group, less common form of aldehydes and ketons

Question 29

Tautomers

Answer 29

Mars that can be entered converted by moving a hydrogen and a double bond, the keto and enol forms are tautomers of each other

Question 30

Michaels addition

Answer 30

An enolate attacks an alpha-beta unsaturated carbonyl, creating a bond

Question 31

Kinetic enolate

Answer 31

Favored by fast, irreversible reactions at lower temperatures with strong, sterically hindered bases

Question 32

Thermodynamic enolate

Answer 32

Favored by slower, reversible reactions at higher temperatures with weaker, smaller bases

Question 33

Enamines

Answer 33

Tautomers of imines, like enols are the less common tautomer

Question 34

Aldol condensation

Answer 34

Aldehyde or ketone acts as both nucleophile and electrophile resulting in the formation of a carbon carbon bond in a new molecule called an aldol, contains both aldehyde and alcohol functional groups, nucleophile is the notate form from the deprotonation of the alpha carbon, the electrophile is the aldehyde or ketone in the form of the keto tautomer

1) condensation reaction occurs when the two molecules come together
2) dehydration reaction occurs which result in an alpha-beta unsaturated carbonyl

Question 35

Retro-aldol reactions

Answer 35

Reverse of aldol condensations, paralyzed by heat and base, the bond between an alpha and beta carbon is cleaved

Question 36

Dehydration reaction

Answer 36

Results in a loss of a water molecule