Organic Chemistry by Brown, Iverson, Anslyn, Foote | Mayya's Study Guide | Chapter 16
- Mayya Alocci
- Aug 25, 2023
- 3 min read
Updated: May 30, 2024
Chapter 16: Aldehydes and Ketones
Table of Contents:
Structure and Bonding
Nomenclature
Aldehydes:
Find the longest continuous carbon chain that contains the aldehyde and number from the carbon with the aldehyde group
End the name in "al"
Ketones:
Find the longest continuous carbon chain that contains the ketone group and number from the carbon closest to the ketone functional group.
End the name in "one" and specify the number of the carbon to which =O is attached.
Physical Properties
Due to the =O, aldehydes and ketones are polar molecules. The carbon with =O is a Lewis acid (can be attacked) and the O is the lewis base (can attack).
Reaction Themes
Carbonyl reactions can happen in acidic and in basic conditions
Addition of Carbon Nucleophiles
1. Addition of Grignard Reagents
Mechanism Of Grignard Addition to the Carbonyls
How to predict the reactants of ketone/aldehyde +RMgBr when product is given?
Mayya's Trick
Break between carbon with OH and its neighboring C
Turn OH into =O and add MgBr (or Li) to the carbon broken off
2. Addition of Anions of Terminal Alkynes
Mechanism
Note: Once alkyne is attached, we can do alkyne reactions on it to produce
other groups.
3. Addition of Hydrogen Cyanide
The Wittig Reaction
Witting reaction converts carbonyls (ketones or aldehydes ) into alkenes (C=C).
Preparing Wittig Reagent
Mechanism for preparing Wittig Reagent
Note: If there is a C=O next to the negative charge on the Wittig Reagent, it will be E selective.
How to predict the reactants when Wittig product is given?
Mayya's Trick
Break between the two carbons that have the double bond
To the most substituted carbon attach =O. To the less substituted carbon attach PPh3. Put negative charge on the carbon with PPh3 and positive charge on P
Addition of Oxygen Nucleophiles
Hemiacetal is a molecule with a carbon that is attached to an OH and an OR group.
An acetal is molecule with a carbon attached to two OR groups.
Formation of hemiacetal under basic conditions
Mechanism
Acetal Formation****(very important)
Mechanism of Acetal Formation
This mechanism may seem a little lengthy. Here is what helps me think about it and do it correctly.
I do the mechanism with the knowledge of what the product should be. The group that needs to leave will be protonated until it becomes a good leaving group. Groups that need to stay will be deprotonated.
Acetals are very useful in serving as protecting groups for ketones and aldehydes.
Protecting of Alcohols as Acetals
Addition of Nitrogen Nucleophiles
Formation of an Imine from an Aldehyde or a Ketone
Note: this reaction uses primary amine. Primary amine has a nitrogen attached to one alkyl group only.
Mechanism for formation of an Imine from an Aldehyde or a Ketone
How to predict the reactants that gave the following amine?
Mayya's Trick
Break between the carbon and nitrogen
Attach =O to the carbon. Attach H to the nitrogen broken off.
Reaction of Aldehyde/Ketone with secondary amine to form an enamine
Keto-Enol Tautomerism
Alpha hydrogens are hydrogens on a carbon next to the C=O group. Alpha hydrogens are acidic. When you take an alpha hydrogen off, the conjugate base is resonance stabilized.
Oxidation
Oxidation of Aldehydes
Reduction
Multiple reagents can be used to reduce ketones and aldehydes to alcohols.
Reductive Amination
Reduction of a Carbonyl Group to a Methylene Group
Complete the following reactions.
Wolff Kishner Mechanism
Reactions at an α-Carbon
Racemization
If the alpha carbon has a specific stereochemistry, it will lose its stereochemistry once it becomes an enol (have a double bond). When it equilibrates back to the keto form, it can have both R or S stereochemistry.
Deuterium Exchange
Alpha Halogenation in Acid
Alpha Halogenation in Base
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