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Questions and Answers
What is the primary product formed from the hydroboration-oxidation of terminal alkynes?
What is the primary product formed from the hydroboration-oxidation of terminal alkynes?
What conditions are required for the Kucherov reaction to occur?
What conditions are required for the Kucherov reaction to occur?
In Friedel-Crafts acylation, what role does AlCl3 play?
In Friedel-Crafts acylation, what role does AlCl3 play?
Which reaction results in the formation of aldehydes from olefins?
Which reaction results in the formation of aldehydes from olefins?
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What is the expected product distribution from the hydroformylation of propylene?
What is the expected product distribution from the hydroformylation of propylene?
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What is the primary product of the Wittig reaction?
What is the primary product of the Wittig reaction?
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What type of rearrangement does the benzilic acid rearrangement involve?
What type of rearrangement does the benzilic acid rearrangement involve?
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Which reagent is used to prepare phosphorus ylides in the Wittig reaction?
Which reagent is used to prepare phosphorus ylides in the Wittig reaction?
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In the mechanism of the Wittig reaction, what does the negative carbon on the ylide attack?
In the mechanism of the Wittig reaction, what does the negative carbon on the ylide attack?
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What is formed when benzoin undergoes oxidation?
What is formed when benzoin undergoes oxidation?
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What is the primary product formed during an aldol condensation reaction?
What is the primary product formed during an aldol condensation reaction?
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Which catalyst is typically used for the Perkin reaction?
Which catalyst is typically used for the Perkin reaction?
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What type of reaction is an intramolecular aldol condensation?
What type of reaction is an intramolecular aldol condensation?
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What reagent is commonly used with aromatic aldehydes in a reaction to produce a β-hydroxy carbonyl?
What reagent is commonly used with aromatic aldehydes in a reaction to produce a β-hydroxy carbonyl?
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In the context of aldol condensation, what product results from dehydration of the β-hydroxy carbonyl
In the context of aldol condensation, what product results from dehydration of the β-hydroxy carbonyl
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Which of the following helps in the retrosynthesis of a given compound in aldol reactions?
Which of the following helps in the retrosynthesis of a given compound in aldol reactions?
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What is the role of Na2CO3 in an aldol condensation reaction?
What is the role of Na2CO3 in an aldol condensation reaction?
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Which of the following describes the initial step in aldol condensation?
Which of the following describes the initial step in aldol condensation?
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What is the role of the lone pair of electrons on oxygen in a carbonyl group?
What is the role of the lone pair of electrons on oxygen in a carbonyl group?
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Which of the following reagents is commonly used in the oxidation of alcohols to produce aldehydes?
Which of the following reagents is commonly used in the oxidation of alcohols to produce aldehydes?
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Which reaction involves the use of ozone (O3) to form aldehydes?
Which reaction involves the use of ozone (O3) to form aldehydes?
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What type of reaction is used to convert alkynes into aldehydes, specifically in Kocherov’s reaction?
What type of reaction is used to convert alkynes into aldehydes, specifically in Kocherov’s reaction?
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What is one industrial application of formaldehyde?
What is one industrial application of formaldehyde?
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Which of the following aldehyde or ketone is NOT miscible with water?
Which of the following aldehyde or ketone is NOT miscible with water?
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What is the product of the reduction of acid chlorides in the process known as Rosenmund’s reduction?
What is the product of the reduction of acid chlorides in the process known as Rosenmund’s reduction?
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What type of compound do acetone and methyl ethyl ketone serve as in industrial applications?
What type of compound do acetone and methyl ethyl ketone serve as in industrial applications?
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What is the primary product formed from a Claisen condensation or Dieckmann cyclization?
What is the primary product formed from a Claisen condensation or Dieckmann cyclization?
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What role does the catalyst play in the Benzoin condensation?
What role does the catalyst play in the Benzoin condensation?
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Which reaction utilizes carboxylic acid groups to induce decarboxylation?
Which reaction utilizes carboxylic acid groups to induce decarboxylation?
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In a Stobbe condensation, what type of product is formed?
In a Stobbe condensation, what type of product is formed?
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What is the first step in the mechanism of the Benzoin condensation?
What is the first step in the mechanism of the Benzoin condensation?
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What distinguishes the Knoevenagel condensation from other condensation reactions?
What distinguishes the Knoevenagel condensation from other condensation reactions?
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Which of the following reactions requires the least strong bases?
Which of the following reactions requires the least strong bases?
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What does the reaction rate of the Benzoin condensation depend on?
What does the reaction rate of the Benzoin condensation depend on?
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What is the typical pKa range for alcohols?
What is the typical pKa range for alcohols?
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In the context of the aldol reaction, what is used to form an enolate?
In the context of the aldol reaction, what is used to form an enolate?
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What characteristic distinguishes enolizable aldehydes from non-enolizable aldehydes?
What characteristic distinguishes enolizable aldehydes from non-enolizable aldehydes?
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Which of the following products is typically formed from crossed aldol reactions of enolizable aldehydes?
Which of the following products is typically formed from crossed aldol reactions of enolizable aldehydes?
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What is a characteristic feature of aldol reactions involving unsymmetrical ketones?
What is a characteristic feature of aldol reactions involving unsymmetrical ketones?
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What are the implications of the Zimmerman–Traxler model in aldol reactions?
What are the implications of the Zimmerman–Traxler model in aldol reactions?
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Which statement regarding weak acids at the α-position is correct?
Which statement regarding weak acids at the α-position is correct?
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During a base-catalyzed aldol reaction, what is the first step?
During a base-catalyzed aldol reaction, what is the first step?
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Which of the following base catalyzed aldol reactions would yield a less hindered product?
Which of the following base catalyzed aldol reactions would yield a less hindered product?
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In a crossed aldol reaction involving an enolizable aldehyde, what is commonly observed?
In a crossed aldol reaction involving an enolizable aldehyde, what is commonly observed?
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Study Notes
Ketones and Aldehydes
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Ketones and aldehydes are carbonyl compounds
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Carbonyl structure: Carbon is sp² hybridized. C=O bond is shorter and stronger, more polar than C=C bond in alkenes.
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Ketone C=O bond length: 1.23 Å
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Ketone C=O bond energy: 178 kcal/mol (745 kJ/mol)
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Alkene C=C bond length: 1.34 Å
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Alkene C=C bond energy: 146 kcal/mol (611 kJ/mol)
Naming Aldehydes
- IUPAC: Replace -e with -al.
- The aldehyde carbon is number 1.
- If -CHO is attached to a ring, use the suffix -carbaldehyde.
Examples
- 3-methylpentanal
- 2-cyclopentenecarbaldehyde
Aldehydes: Common Names
- Formaldehyde (Methanal)
- Acetaldehyde (Ethanal)
- Propionaldehyde (Propanal)
- Butyraldehyde (Butanal)
- 2-Chloropropanal
- 3-Hydroxypropanal
- Benzaldehyde
- p-Nitrobenzaldehyde
- o-Hydroxybenzaldehyde
- p-Methoxybenzaldehyde
- Salicylaldehyde
- Anisaldehyd
IUPAC Names for Ketones
- Replace -e with -one.
- Indicate the position of the carbonyl with a number.
- Number the chain so that the carbonyl carbon has the lowest number.
- For cyclic ketones, the carbonyl carbon is assigned the number 1.
Examples
- 3-methyl-2-butanone
- 3-bromocyclohexanone
- 4-hydroxy-3-methyl-2-butanone
Naming as Substituent
- On a molecule with higher priority functional group, C=O is oxo- and -CHO is formyl.
- Aldehyde priority is higher than ketone.
Common Names for Ketones
- Named as alkyl attachments to -C=O.
- Use Greek letters instead of numbers.
Examples
- Methyl isopropyl ketone
- α-bromoethyl isopropyl ketone
Historical Common Names
- Acetone
- Acetophenone
- Benzophenone
Boiling Points
- More polar, has higher boiling point than comparable alkane or ether.
- Cannot form H-bonds with each other, so has lower boiling point than comparable alcohols.
Solubility
- Good solvent for alcohols.
- Lone pair of electrons on oxygen of carbonyl can accept a hydrogen bond from O-H or N-H.
- Acetone and acetaldehyde are miscible in water.
Industrial Importance
- Acetone and methyl ethyl ketone are important solvents.
- Formaldehyde is used in polymers like Bakelite.
- Flavorings and additives like vanilla, cinnamon, and artificial butter.
Preparation of Aldehydes and Ketones
- Oxidation of alcohols
- Reduction of acid chlorides
- Ozonolysis of alkenes
- Hydration of alkynes (Kocherov's reaction) -Hydroboration-oxidation
- Friedel-Crafts acylation
- Hydroformylation reaction
- Gattermann-Koch reaction
- Reimer-Tiemann reaction
- Oxidation of an alkyl side of aromatic ring.
- From acid chloride and lithium dialkyl cuperate or R₂Cd
- From nitriles and Grignard reagent or alkyl lithium
- From carboxylates
Knoevenagel
- Condensation of active methylene compounds with aldehydes
- To give a, β-unsaturated compounds
Stobbe Condensation
- Modification for diethyl ester of succinic acid
Benzoin Condensation
- Condensation of aldehydes devoid of α-hydrogen
- Preparation of α-hydroxyketones
Wittig Reaction
- Nucleophilic addition of phosphorous ylides
- Product is alkene (C=C)
Phosphorus Ylides
- Prepared from triphenylphosphine and unhindered alkyl halide.
- Butyllithium abstracts a hydrogen from the carbon attached to phosphorous
Mechanism of Wittig Reaction
- The negative C on ylide attacks the positive C of carbonyl to form a betaine.
- Oxygen combines with phosphorous to form phosphorous oxide.
Oxidation of Aldehyde
- Easily oxidized to carboxylic acids
Tollens Test
- Add ammonia solution to AgNO3 solution until precipitate dissolves.
- Aldehyde reaction forms a silver mirror.
Iodoform Reaction
- Oxidation of a methyl ketone to a carboxylate.
- Alpha position to carbonyl easily halogenated.
Cannizzaro Reaction
- Redox disproportionation of non-enolizable aldehydes.
- Gives carboxylic acids and alcohols.
Aldol Reactions
- Condensation reaction of two carbonyl compounds.
Intramolecular Aldol Condensation
- Even ketones give good yields when reaction is intramolecular.
Aromatic Aldehydes
- Reaction of aldehydes with reactive methyl group.
Perkin Reaction
- α,β-unsaturated aromatic acid by aldol type condensation.
- Aromatic aldehydes, acid anhydride with an alkali salt.
Claisen Condensation
- Base-promoted condensation of two esters.
- To give β-keto-ester product.
Crossed Claisen Condensations
- Similar restrictions as mixed aldol condensation.
Dieckmann Cyclization
- Intramolecular Claisen Condensation.
Acylation of Ketones with Esters
- Alternative to Claisen condensations.
- Dieckmann cyclization.
Meerwein-Ponndorf-Verley reduction
- Reduction of carbonyl to alcohols using aluminum alkoxide catalysts.
- Chemoselective (aldehydes reduced before ketones).
Oppenauer oxidation
- Oxidation of secondary alcohols to ketones.
- Opposite to MPV reduction.
Deoxygenation
- Reduction of C=O to CH2
- Two methods:
- Clemmensen reduction (stable in acid)
- Wolff-Kishner reduction (stable in strong base)
Clemmensen Reduction
- Deoxygenation of aldehydes or ketones to hydrocarbons.
Wolff-Kishner Reduction
- Deoxygenation using hydrazine and a strong base.
Huang Minlon Modification
- Modification to the Wolff-Kishner reduction.
- Refluxing the carbonyl substrate with hydrazine hydrate and sodium hydroxide in ethylene glycol.
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