1. Aldehydes and Ketones

2. Before you can learn about aldehydes and ketones, you must first know something about the nomenclature of carboxylic acids since many of the names of aldehydes and ketones are derived from the names of the corresponding carboxylic acids.

3. Carboxylic acids:
R-COOH, R-CO2H,
Common names:
HCO2H formic acid L. formica ant
CH3CO2H acetic acid L. acetum vinegar
CH3CH2CO2H propionic acid G. “first salt”
CH3CH2CH2CO2H butyric acid L. butyrum butter
CH3CH2CH2CH2CO2H valeric acid L. valerans

4. Carboxylic acids, common names:…
CH3(CH2)4CO2H caproic acid L. caper goat
CH3(CH2)5CO2H ---
CH3(CH2)6CO2H caprylic acid
CH3(CH2)7CO2H ---
CH3(CH2)8CO2H capric acid
CH3(CH2)9CO2H ---
CH3(CH2)10CO2H lauric acid oil of lauryl

5.
C—C—C—C—C=O
δ γ β α used in common names

6. Special names!

7. ALDEHYDES AND KETONES
“carbonyl” functional group:
Aldehydes Ketones

8. Nomenclature:
Aldehydes, common names:
Derived from the common names of carboxylic acids;
drop –ic acid suffix and add –aldehyde.
CH3
CH3CH2CH2CH=O CH3CHCH=O
butyraldehyde isobutyraldehyde
(α-methylpropionaldehyde)

10. Aldehydes, IUPAC nomenclature:
Parent chain = longest continuous carbon chain containing the carbonyl group; alkane, drop –e, add –al. (note: no locant, -CH=O is carbon #1.)
CH3
CH3CH2CH2CH=O CH3CHCH=O
butanal methylpropanal
H2C=O CH3CH=O
methanal ethanal

11. Ketones, common names:
Special name: acetone
“alkyl alkyl ketone” or “dialkyl ketone”

12. (o)phenones:
Derived from common name of carboxylic acid, drop –ic acid, add –(o)phenone.

13. Ketones: IUPAC nomenclature:
Parent = longest continuous carbon chain containing the carbonyl group. Alkane, drop –e, add –one. Prefix a locant for the position of the carbonyl using the principle of lower number.

14. Physical properties:
polar, no hydrogen bonding
mp/bp are relatively moderate for covalent substances
water insoluble
(except: four-carbons or less)

15. Spectroscopy:
IR: C=O stretch, strong ~1700 cm-1
RCHO ArCHO 1700
R2CO ArCOR 1690
C—H stretch for aldehydes 2720
nmr: -CHO 9-10 ppm

16. acetophenone
C=O
stretch

17. valeraldehyde
CHO
C—H
stretch
2720 cm-1
C=O stretch

18. valeraldehyde
CH3CH2CH2CH2CH=O
a b c d e
-CHO

19. Oxidation/Reduction:
oxidation numbers:
oxidation
CH CH3OH H2C=O HCO2H CO2
alkane alcohol aldehyde carboxylic acid
reduction

20. Aldehydes, syntheses:
Oxidation of 1o alcohols
Oxidation of methylaromatics
Reduction of acid chlorides
Ketones, syntheses:
Oxidation of 2o alcohols
Friedel-Crafts acylation
Coupling of R2CuLi with acid chloride

21. Aldehydes synthesis 1) oxidation of primary alcohols:
RCH2-OH K2Cr2O7, special conditions  RCH=O
RCH2-OH C5H5NHCrO3Cl  RCH=O
(pyridinium chlorochromate)
[With other oxidizing agents, primary alcohols  RCOOH]

23. Aldehyde synthesis: 2) oxidation of methylaromatics:
Aromatic aldehydes only!

25. Aldehyde synthesis: 3) reduction of acid chloride

27. Ketone synthesis: 1) oxidation of secondary alcohols

28. Ketone synthesis: 2) Friedel-Crafts acylation
Aromatic ketones (phenones) only!

29. Friedel Crafts acylation does not work on deactivated rings.

31. Ketone synthesis: 3) coupling of RCOCl and R2CuLi

33. Aldehydes, syntheses:
Oxidation of 1o alcohols
Oxidation of methylaromatics aromatic only
Reduction of acid chlorides
Ketones, syntheses:
Oxidation of 2o alcohols
Friedel-Crafts acylation aromatic only
Coupling of R2CuLi with acid chloride

34. K2Cr2O7, special cond.
or C5H5NHCrO3Cl
1o alcohol
Ar-CH3
CrO H2O
(AcO)2O
aldehyde
acid chloride
LiAlH(O-t-Bu)3

35. 2o alcohol
NaOCl, etc.
ketone
acid chloride + ArH
AlCl3
acid chloride + R2CuLi

36. outline three different syntheses for benzaldehyde
outline three different syntheses for benzophenone
outline a different synthesis for each of the following compounds:
cyclohexanone, 4-bromobenzaldehyde, 2-pentanone, valeraldehyde, acetophenone, isobutyraldehyde,

37. Synthesize benzaldehyde three different ways.

38. Synthesize benzophenone three different ways.

39. cyclohexanone, 4-bromobenzaldehyde, 2-pentanone, valeraldehyde, acetophenone, isobutyraldehyde, using a different method for each one.

41. The methods could be reversed for the last two syntheses.