Reactions of Aldehydes and Ketones Overview
Overview/Topics
1.
ID
a.
Aldehyde
b.
Ketone
c.
Alcohol
d.
Ether
e.
Carboxylic Acid
f.
Hemiacetal/Acetal/Hemiketal/Ketal
2.
Reactions!
a.
Additions Reactions
•
Reduction/Hydrogenation (+ H
2
)
•
Cyanohydrin (+ HCN)
•
Hemiacetal/Hemiketal (+ Alc)
b.
Dehydration (-H
2
O)
c.
Oxidation/Diagnostic Tests
d.
Aldol Condensation
Skills to Master
1.
HW 23b
Read
Chapter 23.4
CHE 102 Spring 2021
Lecture 23b – Reactions of Ald/Ket
Review – Functional Groups
Aldehyde
Ketone
Carboxylic Acid (CA)
Carboxylic Acid Salt
Review – Functional Groups
Hemiacetal
Hemiketal
Acetal
Ketal
Oxidation (Review) Diagnostic Tests
Aldehyde
Carboxylic Acid (CA)
Ketone
No Reaction (NR)
Review
Tollens Reactions
“Silver Mirror Test”
What is oxidized?
What is reduced?
Positive (+) for aldehydes
Negative (-) for ketones
Fehlings/Benidicts
Aldehyde + 2 Cu
+2
(aq) + NaOH (aq)
Carboxylic Acid Salt + 2 Cu
2
O (s) + H
2
O
Visible Change: blue to “brick red ppt”
Ketone + 2 Cu
+2
(aq) + NaOH (aq)
NR
What is oxidized?
What is reduced?
Positive (+) for aldehydes
Negative (-) for ketones
Examples:
Oxidation – Diagnostic Tests
Addition Reactions
Reduction – gain bonds to H
Hydrogenation
Things to add:
H
2
HCN
R-OH
Reaction Mechanism – Yuck!
Examples:
Reduction – gain bonds to H
Hydrogenation
Examples:
Examples:
Dehydration Reactions
Hemiacetal
+ Alcohol
Acetal + H
2
O
Hemiketal + Alcohol
Ketal + H
2
O
Play “Find the Water” again!
Examples:
Aldol Condensation
o
“Self-Addition”
o
Condensation (Adding 2 molecules together)
o
α-hydrogen = most reactive
o
Product = Aldol =
β
-hydroxy ald/ket
Multiple products if…..
o
Unsymmetrical aldehyde or ketone
o
Aldehyde + Ketone
Yucky Mechanism
Examples:
Examples:
Examples:
Summary – Ch. 23
Reaction Type
Mechanism
Misc
Recognize
Memorize
Gain Bond O
Dehydration
Find the Water
Addition
Misc Arrow
C=O + something
Break C=O add
“something” to
both sides
Single Product
Blue → Red (ppt)
14 Reaction → 3 Reactions
Silver Mirror
Tollens
Fehling/Benedict
CA Salts!
2 -OH
+H
2
O
Aldol
Condensation
“Fancy” Addition
α
-hydrogen
Multiple Prod.
β-hydroxyl ald/ket
Summary – Ch. 22
Reaction Type
Mechanism
Misc
Oxidation
Recognize
Memorize
Gain Bond O
Dehydration
Find the Water
Substitution
2 Reactants
(not Oxid or Dehyd)
Swap
Na loves Cl
Lucas Test
Chromic Acid Test
14 Reaction → 3 Reactions
You Try It:
You Try It:
You Try It:
In this content, you will find a comprehensive overview of reactions involving aldehydes and ketones. Topics covered include addition reactions, dehydration, oxidation, diagnostic tests, Aldol condensation, and more. Visual aids and examples are provided to enhance understanding.
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Presentation Transcript
CHE 102 Spring 2021 Lecture 23b Reactions of Ald/Ket Overview/Topics Skills to Master 1. ID 1. HW 23b Aldehyde Ketone Alcohol Ether Carboxylic Acid Hemiacetal/Acetal/Hemiketal/Ketal 2. Reactions! a. Additions Reactions Reduction/Hydrogenation (+ H2) Cyanohydrin (+ HCN) Hemiacetal/Hemiketal (+ Alc) b. Dehydration (-H2O) c. Oxidation/Diagnostic Tests d. Aldol Condensation a. b. c. d. e. f. Read Chapter 23.4
Review Functional Groups Aldehyde Ketone Carboxylic Acid (CA) Carboxylic Acid Salt
Review Functional Groups Hemiacetal Hemiketal Acetal Ketal
Review Oxidation (Review) Diagnostic Tests [O] Aldehyde Carboxylic Acid (CA) [O] Ketone No Reaction (NR)
What is oxidized? What is reduced? Tollens Reactions Silver Mirror Test Positive (+) for aldehydes Negative (-) for ketones [O] Aldehyde + 2 Ag+ (aq) + NH3 (aq) Carboxylic Acid Salt + 2 Ag (s) Visible Change: Clear to Silver Mirror [O] Ketone + 2 Ag+ (aq) + NH3 (aq) NR
What is oxidized? What is reduced? Positive (+) for aldehydes Negative (-) for ketones Fehlings/Benidicts [O] Aldehyde + 2 Cu+2 (aq) + NaOH (aq) Carboxylic Acid Salt + 2 Cu2O (s) + H2O Visible Change: blue to brick red ppt [O] Ketone + 2 Cu+2 (aq) + NaOH (aq) NR
Examples: Oxidation Diagnostic Tests
Addition Reactions [H2/Ni] [H2/Ni] Reduction gain bonds to H Hydrogenation Aldehyde Primary Alcohol Ketone Secondary Alcohol [OH-] Ald/Ket + HCN Cyanohydrin [H+] Aldehyde + Alcohol Hemiacetal [H+] Things to add: H2 HCN R-OH Ketone + Alcohol Hemiketal
Examples: [H2/Ni] [H2/Ni] Reduction gain bonds to H Hydrogenation Aldehyde Primary Alcohol Ketone Secondary Alcohol
Examples: [OH-] Ald/Ket + HCN Cyanohydrin
Examples: [H+] Aldehyde + Alcohol Hemiacetal [H+] Ketone + Alcohol Hemiketal
Dehydration Reactions [dry HCl] Acetal + H2O Play Find the Water again! Hemiacetal + Alcohol [dry HCl] Ketal + H2O Hemiketal + Alcohol
Yucky Mechanism Aldol Condensation o Self-Addition o Condensation (Adding 2 molecules together) o -hydrogen = most reactive o Product = Aldol = -hydroxy ald/ket Aldehyde + Aldehyde [dilute NaOH] Aldehyde + Ketone Aldol ( -hydroxy ald/ket) Multiple products if .. o Unsymmetrical aldehyde or ketone o Aldehyde + Ketone Ketone + Ketone
Examples: [dilute NaOH] Aldehyde + Aldehyde Aldol ( -hydroxyl ald/ket)
[dilute NaOH] Ketone + Ketone Examples: Aldol ( -hydroxyl ald/ket)
Examples: [dilute NaOH] Aldehyde + Ketone Aldol ( -hydroxyl ald/ket)
Summary Ch. 23 14 Reaction 3 Reactions Reaction Type Recognize Mechanism Misc Silver Mirror Memorize Gain Bond O CA Salts! [O] Tollens Fehling/Benedict Blue Red (ppt) Break C=O add something to both sides Misc Arrow C=O + something Single Product Addition [dry HCl] Find the Water Dehydration +H2O 2 -OH Multiple Prod. -hydroxyl ald/ket Aldol Condensation -hydrogen Fancy Addition
Summary Ch. 22 14 Reaction 3 Reactions Reaction Type Recognize Mechanism Misc Memorize Gain Bond O [O] Chromic Acid Test Oxidation [-H2O] Find the Water Dehydration 2 Reactants (not Oxid or Dehyd) Na loves Cl Lucas Test Swap Substitution
