1. Organic Chemistry Aldehydes and Ketones
Chapter 17

2. Aldehydes and Ketones Carbonyl Group C=O Aldehydes Ketones
Present in aldehydes and ketones
Aldehydes
Ketones

3. Aldehydes Aldehydes Aldehydes Sometimes abbreviated RCHO
Contain at least one H connected to the C
Aldehydes

4. Ketones Ketones Ketones Carbonyl C is connected to two alkyl groups
RCOR’
Ketones

5. Nomenclature IUPAC Suffix is “-al” for the aldehydes
Suffix is “-one” for the ketones
# indicates position of ketone

6. Nomenclature
NOTE:
Ketone,
Not keytone
From Yahoo Images

7. Nomenclature
An Aldehyde or Ketone takes precedence over any previously considered group

8. Nomenclature
Common names - aldehydes

9. Nomenclature Common names - ketones Some are always used
- Others name each R group and end with “ketone”

10. Physical Properties Carbonyls: Cannot form H bonding with each other:
There is NOT an H connected to a F, N, O
Aldehydes and Ketones are POLAR molecules and form dipole interactions
Gives higher boiling and melting points

11. Physical Properties Aldehydes and Ketones can form H bonds with water!
solubility in water is about the same as alcohols
yes!

12. Physical Properties Strong odors Ketones generally have pleasant odors
perfumes, flavoring agents
Aldehydes odors vary
some pleasant
cinnaminaldehyde, vanillin
some not pleasant
formaldehyde
Many are found in natural products

13. How do you make Aldehydes?
Aldehydes from Oxidation of 1o alcohols
Problem is over oxidation to ACID!
Practice a couple …………..

14. How do you make Ketones? Ketones from Oxidation of 2o alcohols
Practice a couple …………..

15. Oxidation of Aldehydes
Aldehydes are easily oxidized
KMnO4
K2Cr2O7
even air oxidation carboxylic acid!

16. Oxidation of Ketones Ketones resist oxidation:
under mild or normal conditions, no reaction
more severe conditions yield mixtures
CO2 and H2O under extreme conditions
[O]
This difference in reactivity can be used to
Tell the difference between an aldehyde and ketone

18. Reaction 1. Oxidation – Tollens Test - Benedicts Test
2. Reduction – Hydrogen addition
– NaBH4 reagent
3. Addition of Alcohols – hemiacetal/acetal
and tautomerism

19. Tollen’s Test The Silver Mirror Test Ag(NH3)2+ + aldehyde
Oxidation of Aldehydes
Ag+ ion in aq. ammonia
NO reaction with KETONES
Ag(NH3) aldehyde
Silver Mirror
Ag NH Ag(NH3)2+
Ag(NH3)2+ + RCHO Ago + RCOO- + 4NH3

20. Benedict’s Test Cu++ + aldehyde Cu+(oxide) + acid
Oxidation of Aldehydes
Cu++ ion, aqueous
Orange to red ppt.
NO reaction with KETONES
Cu2+
Cu+
Cu aldehyde Cu+(oxide) acid

21. Benedict’s Test
Oxidation of Aldehydes
overall reaction
Cu2O

22. Chemical Properties - Addition to C=O
Other reactions are ADDITION Reactions
Bond is polar + and -
Negatives are attracted to C
Positives are attracted to O - + B

23. Addition of H2 Reduction to Alcohols
Hydrogen gas and a catalyst (Ni, Pd, Pt)
Similar to alkene to alkane reduction B

24. Addition of H2 Reduction to Alcohols
Will reduce ketones to 2o alcohols
Slower reaction than reduction of C=C
C=C is reduced faster (first) if both C=O and C=C B

25. Addition of H2 using NaBH4
Reduction to Alcohols
NaBH4 does not allow the reaction of the carbon carbon double bond B

26. Addition of Alcohol
In the addition of R-OH to form an “acetal” the First step is the formation of a “hemiacetal”
This is when an -OH and -OR are both on same C B

27. Formation of Acetals
IF strong acid (HCl) is present, a second alcohol reacts to form the acetal (two -OR groups on C)
+ H2O B

28. Addition of Alcohol - Acetals
Step 1
Step 2
+ H2O B

29. Formation of Acetals ? Addition of R-OH
acid catalyzed, 2 moles of alcohol react ? B

30. Formation of Acetals Addition of R-OH
acid catalyzed, 2 moles of alcohol react
Draw the Hemi B

31. Formation of Acetals
Acetal reaction in equilibrium B

32. Formation of Acetals
Acetal reactions ? B

33. Formation of Acetals
Acetal reactions ?
1o alcohol B

34. Formation of Acetals Hemiacetal reactions (formation of hemiacetals)
likely when within the same molecule CH 2 O OH or H
a cyclic hemiacetal 1 3 4 5
1o alcohol B

35. Formation of Acetals Cyclic hemiacetals
Reacts with a 2nd. molecule of alcohol
Results in a cyclic acetal
1o alcohol B

36. Formation of Acetals Which are hemiacetals / acetals? 1 2 3 4 5 6 7 89 10 B

37. Keto-Enol Tautomerism
Equilibrium that exists
Keto (carbonyl) to Enol (alkene/alcohol) B

38. Keto-Enol Tautomerism
Equilibrium called Tautomerism
Keto form
(more stable)
(less stable)
1o alcohol B

39. Keto-Enol Tautomerism
Equilibrium called Tautomerism
Most enols are
less stable
1o alcohol B

40. Important Compounds Formaldehyde Gas at RT Soluble in H2O Formalin
found in labs
preserves by denaturing proteins
Used to produce polymers B

41. Important Compounds Acetaldehyde bp 21o C Converted to trimer
3 units of acetaldehyde
called paraldehyde
once used as a hypnotic/sleep-producer B

42. Important Compounds Acetone bp 56o C Infinitely soluble in H2O
Excellent industrial solvent:
paints, varnishes, resins
coatings, nail polish
Produced in the body
diabetic ketoacidosis
“acetone breath” B

43. Important Compounds -chloroacetophenone lachrymators
tearing of eyes, etc.
Used as a tear gas
Active ingredient in “Mace” B