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www.clutchprep.com ORGANIC - BROWN 8E CH. 16 - ALDEHYDES AND KETONES
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ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

CONCEPT: ALDEHYDE NOMENCLATURE

Replace the suffix of the alkane “-e” with the suffix __________

● On the parent chain, the carbonyl is always terminal, and ____________ receive a location

● As substituents, they receive the name ______________________________ and _____ receive a location

EXAMPLE: Correctly name the following aldehyde.

EXAMPLE: Correctly name the following aldehyde.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 2

CONCEPT: KETONE NOMENCLATURE

Replace the suffix of the alkane “-e” with the suffix __________

● Ketones have higher priority than most groups in Orgo 1, including alcohols

● When assigning common names to ketones, name both R-groups alphabetically, ending with “______________”

EXAMPLE: Correctly name the following ketone.

1.

EXAMPLE: Correctly name the following ketone.

2.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 3

CONCEPT: INTRO TO REDOX

● Oxidation reactions involve an increase in the ______________ content of a molecule

● Reduction reactions involve an increase in the ______________ content of a molecule

EXAMPLE: Label the following transformations as oxidation or reduction.

a.

b.

c.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 4

CONCEPT: NUCLEOPHILIC ADDITION

□ One of the most important ways that carbonyl compounds react is through nucleophilic addition.

● The carbonyl carbon is _____________________________

Nucleophilic Addition General Mechanism:

Nucleophilic Addition General Reactions:

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 5

CONCEPT: ORGANOMETALLICS

1. Nucleophilic Addition on Ketones and Aldehydes

EXAMPLE: Show the mechanism and predict the product for the following reaction.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 6

PRACTICE: Provide the major product for the following reaction.

 

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 7

PRACTICE: Provide the major product for the following reaction dealing with the Grignard reagent.

Br

Mg

Ether (ROR)

O

H3O+

 

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 8

PRACTICE: Provide the major product for the following reaction dealing with the Grignard reagent.

 

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 9

PRACTICE: Provide the major product for the following reaction dealing with the Grignard reagent.

Br

OH

TMS-Cl

N(Et)3

A

Mg

Ether (ROR)

O

H3O+

B C

 

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 10

CONCEPT: CYANOHYDRINS

Cyanide Addition: Cyanohydrins

Cyanohydrin Hydrolysis: Cyanohydrin Reduction:

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 11

PRACTICE: Provide the major product for the following reaction.

 

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 12

CONCEPT: THE WITTIG REACTION

The Wittig forms new carbon-carbon bonds between carbonyl and reactive intermediate called an “ylide” to yield

regiospecific _____________

Formation of the Ylide:

● STEP 1 – Alkyl Halide + Triphenylphosphine

● STEP 2 – Deprotonation with a Strong Base

● STEP 3 – Form Oxaphosphetane (mechanism) or Box-Out Method (product).

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 13

PRACTICE: Determine the carbonyl and ylide that formed the following product.

 

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 14

CONCEPT: NUCLEOPHILIC ADDITION OF SOLVENTS

These are reactions that are induced primarily by the extraordinary reactivity at the carbonyl carbon

● The carbonyl carbon is so reactive that it even reacts with some _________________

● Most of these mechanisms are acid-catalyzed — all are fully reversible in mild acid (H3O+).

□ Protonation is always the first step, deprotonation is always the last (restores the catalyst)

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 15

CONCEPT: HYDRATES

Carbonyl + Water

● In carbonyls with large –R groups, the equilibrium is greatly shifted to the ____________

EXAMPLE: Show the mechanism and predict the equilibrium for the following reaction.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 16

CONCEPT: HEMIACETALS

Technically, an __________ is the product of alcohol and aldehyde, while ____________ is alcohol and ketone.

● We will simply use the word “acetal” to represent these gem-diether structures in general

● Hemiacetals are only stable when they are ________________.

Carbonyl + 1 Eq. Alcohol

● Acid-Catalyzed Hemiacetal Formation

● Base-Catalyzed Hemiacetal Formation

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 17

CONCEPT: ACETALS

Acetals are stable in ____________ and are easily hydrolyzed back to carbonyls using _________

● Cyclic acetals are formed by reacting carbonyls with a ______________

Carbonyl + 2 Eq. Alcohol

● Acid-Catalyzed Hemiacetal Formation

● Acid-Catalyzed Acetal Formation

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 18

PRACTICE: Provide the chemical steps necessary for the following synthesis.

O

?O O

 

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 19

PRACTICE: Provide the chemical steps necessary for the following synthesis.

 

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 20

PRACTICE: Determine the starting materials based on the acetal group present.

O

O

 

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 21

CONCEPT: ACETALS AS PROTECTING GROUPS

There is a huge difference in reactivity between a carbonyl and an acetal. Which do you think is more reactive?

Acetals are used to protect sensitive aldehydes and ketones from reaction with other reagents, since they are reversible.

EXAMPLE: Propose a reagent to perform the following transformation. More than one reagent may be required.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 22

PRACTICE: Provide the chemical steps necessary for the following synthesis.

 

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 23

PRACTICE: Provide the chemical steps necessary for the following synthesis.

H

NO

H CH3

OO?

 

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 24

CONCEPT: THIOACETALS AND RANEY NICKEL REDUCTION

Via an almost identical mechanism, thiols can react with aldehydes and ketones to produce thioacetals

The Raney nickel catalyst is a convenient way to _____________________ carbonyls altogether

EXAMPLE: Predict the products of the following reaction

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 25

CONCEPT: IMINES AND ENAMINES

Primary Amine Addition: Imines Secondary Amine Addition: Enamines

□ All products produce iminium cation, where the deprotonation step will depend on type of amine used.

Imine Mechanism:

Enamine Mechanism:

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 26

CONCEPT: ADDITION OF AMMONIA DERIVATIVES

EXAMPLE: Predict the products of the following reaction.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 27

CONCEPT: OXIDATION

□ Oxidizing agents are used to oxidize molecules

● Most oxidizing agents add as much oxygen as possible while not breaking ANY C-C bonds.

EXAMPLE: Which of the following compounds could be oxidized?

□ These are called strong oxidizing agents. They include KMnO4 and the Cr6+ reagents (H2Cr2O4, CrO3, K2Cr2O7, etc.)

EXAMPLE: Draw the products of the previous molecules with a strong oxidizing agent

□ PCC is a weak oxidizing agent. It reacts similar but can only add ____ equivalent of oxygen to 1º alcohols.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 28

PRACTICE: Provide the major product for the following oxidation reaction.

CH3

CH3 CH3

OHOH

OH PCC

CH2Cl2

PRACTICE: Provide the major product for the following oxidation reaction.

CH3CH2 1. O3

2. Zn, CH3CO2H

PRACTICE: Provide the major product for the following oxidation reaction.

KMnO4

H+

OH

OH

OH

PRACTICE: Provide the major product for the following oxidation reaction.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 29

PRACTICE: Determine the major product for the following reaction.

PRACTICE: Determine the major product for the following reaction.

PRACTICE: Provide the necessary reagents for the following transformation.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 30

CONCEPT: WEAK OXIDATIVE CLEAVAGE

Ozonolysis: Ketones + Aldehydes + Formaldehyde

PRACTICE: Predict the products of the following reaction

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 31

CONCEPT: ALDEHYDES VIA REDUCING AGENTS

All of the reducing agents we have learned so far are so powerful that they yield alcohols.

● We need to use milder reducing agents to yield aldehydes.

1. Typical strong reduction of carbonyls is accomplished via the use of ____________________

2. We can reduce the power of the reducing agent by making it sterically hindered: _________________________

3. There is another reagent we can use to only induce one equivalent of hydrogen to a carbonyl: _____________

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 32

CONCEPT: REDUCTIVE AMINATION

Recall that ketones and aldehydes can react with primary amines in acidic conditions to form imines.

● This mechanism passed through an important intermediate called an iminium cation.

Ketones and aldehydes can be made to form amines instead by using the reducing agent, NaBH3CN on the imine.

● This mechanism starts the same, except for the fact that we reduce the imine instead of deprotonating it

EXAMPLE: Provide the major product for the following reaction.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 33

CONCEPT: ALKYNE HYDRATION

□ Vinyl alcohols are uniquely reactive due to a phenomenon called tautomerization.

● They reversibly swap the positions of a ___________ and a _____ bond.

Oxymercuration of Alkynes

□ Product: __________________________

Hydroboration of Alkynes

□ Product: __________________________

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 34

CONCEPT: WOLFF-KISCHNER REDUCTION

This reaction sequence is used to completely remove carbonyls from alkane chains, much like:

a. _______________________________

b. _______________________________

Mechanism:

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 35

CONCEPT: ALPHA CARBONS AND TAUTOMERIZATION

We have discussed the high reactivity of the carbonyl carbon.

However, carbonyls contain another highly reactive component.

● What is the acidity of the β-carbon? ____________

● What is the acidity of the α-carbon? ____________

● Which phenomenon is responsible for this difference?

Tautomerization General Reaction:

Acid-Catalyzed Mechanism:

Base-Catalyzed Mechanism:

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 36

PRACTICE: Draw the enol tautomer for the following compound.

Cyclopentanone

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 37

CONCEPT: TAUTOMERS OF DICARBONYL COMPOUNDS

● Most carbonyl compounds favor the ______________ tautomer

● β-dicarbonyl compounds favor the _____________ tautomer due to _________________ and _____________________

● β-dicarbonyl compounds are exceptionally acidic due to the high stability of the conjugate base

● If the α-carbon exists as a chiral center, that carbon will ALWAYS BE ____________________

EXAMPLE: Which of the following ketones is the most acidic?

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 38

CONCEPT: ENOLATES

Upon deprotonation, the α-carbon forms a resonance-stabilized intermediate structure called an _________________

● Both notations can be used to represent an enolate

● Note that the negative charge now rests on the _____________________

● This makes the α-carbon of the enolate a good __________________________

General Reactions of Enolates:

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 39

CONCEPT: ELECTROPHILIC α-HALOGENATIONS

Acid-Catalyzed α-halogenation: Always yields _________-halogenation

PRACTICE: Provide the major product for the following reaction.

CH3

OBr2

H+

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 40

CONCEPT: ELECTROPHILIC α-HALOGENATIONS

Base-Catalyzed α-halogenation: May yield _________-halogenation

PRACTICE: Provide the major product for the following reaction.

OBr2 excess

NaOH

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 41

CONCEPT: ELECTROPHILIC α-HALOGENATIONS

The Haloform Reaction: Base-Catalyzed α-halogenation of _______________ ______________

● The α-carbon is transformed into a good ________________________ through successive halogenations.

PRACTICE: Provide the major product for the following reaction.

OBr2 excess

NaOH

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 42

PRACTICE: Provide the major product for the following reaction.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 43

PRACTICE: Provide the major product for the following reaction.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 44

PRACTICE: Provide the chemical steps necessary for the following synthesis.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 45

PRACTICE: Provide the major product for the following reaction dealing with the Grignard reagent.

ORGANIC - BROWN 8E

CH. 16 - ALDEHYDES AND KETONES

Page 46


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