Chapter 3 ketone

1. Chapter 3: KETONE
Norfazrin Mohd Hanif
Faculty of Applied Science
UiTM Negeri Sembilan

2. SUBTOPICS
Nomenclature
– common and IUPAC names for ketones

Physical properties of ketones : Boiling points and solubility

Preparation of ketone
Oxidation of 2 °Alcohol
Friedel – Crafts Acylation

Reactions of aldehyde
Reduction To 2 ° Alcohol
Nucleophilic Addition
Reaction with Grignard Reagent
Iodoform Reaction

3. •Functional group: carbonyl group CO C
O
R'R
ketone
R, R' = substituents
Ketone: the carbon atom in the carbonyl group is
bonded to two hydrocarbon groups.
Ketones

4. •The IUPAC name of a ketone is derived from the
name of the alkane corresponding to the longest
carbon chain that contains the ketone-carbonyl
group.

•The parent name is formed by changing the –e
ending of the alkane to -one.
propane propanone one
IUPAC NAME

5. If the carbon chain is longer than 4 carbons,
it’s numbered so that the carbonyl carbon has
the smallest number possible, and this
number is prefixed to the name of the ketone.


This end of the chain is closest to the C=O.
Begin numbering here.
IUPAC NAME

6. IUPAC name: 3-hexanone
New IUPAC name: hexan-3-one
4 3 2 1 5 6
IUPAC NAME

7. 7
Common Names of Ketones ::
RC
O
R' alkyl alkyl ketone
•Most common names for ketones are formed
by naming both alkyl groups on the carbonyl
carbon, arranging them alphabetically, and
adding the word “ketone”.

8. cyclohexanone 4-methylcyclohexanone
O
O
CH
3
1
2
3
4
5
6 phenylethanone diphenylmethanone
C
O
CH
3 C
O Aromatic compound:
- phenyl is used as part of the name.
•The parent name is formed by changing the –e ending of the
cycloalkane to -one.
•Carbonyl carbon is designated C1.
NOMENCLATURE OF CYCLIC KETONES
AND AROMATIC COMPOUNDS

9. A ketone group can also be named as a substituent on
a molecule with another functional group as its root.
The ketone carbonyl is designated by the prefix oxo-.
Carboxylic acids frequently contain ketone group
named as substituents. CH
2C
O
CCH
3CH
2
O
H CH
2C
O
CCH
3
O
OH
3-oxopentanal
12345
3-oxobutanoic acid
1234
NOMENCLATURE OF KETONES CONTAINING
TWO DIFFERENT FUNCTIONAL GROUPS

10. 10
Physical Properties : Boiling point
• Oxygen is more electronegative than carbon (3.5
vs 2.5) and, therefore, a C=O group is polar







•Ketones are polar due to this C=O bond and
therefore have stronger intermolecular forces than
hydrocarbons making their boiling points higher.


CO CO
–
Polarity of a
carbonyl group
-+
CO
+
More important
contributing
structure
:
::: :

11. 11
11
Physical Properties : solubility
The small ketones are freely soluble in water but solubility falls
with chain length.

The reason for the solubility is that they can form hydrogen
bond with water molecules.

One of the slightly positive hydrogen atoms in a water
molecule can be sufficiently attracted to one of the lone pairs
on the oxygen atom of a ketone for a hydrogen bond to be
formed.

12. 12
12
Physical Properties : solubility
• Ketones can form hydrogen bonds with water and therefore low
molecular weight ketones have appreciable water solubility

13. 13
PreparationS
OXIDATION OF 2 °ALCOHOL
FRIEDEL – CRAFTS ACYLATION

14. 14
• Examples
• Ketones can be made from 2
o
alcohols by oxidation
* [O] =

2.1 Oxidation of 2 °Alcohol

15. 15
• Aromatic ketones can be made by Friedel-Crafts Acylation
• Examples


2.2 Friedel – Crafts Acylation

16. 16
REACTIONS
REDUCTION TO 2 ° ALCOHOL
NUCLEOPHILIC addition
REACTION with grignard reagent
IODOFORM REACTION

17. REACTIONS OF KETONES
Reduction
Addition
Condensation
Iodoform reaction
Reaction with Grignard reagent

18. Ketones can be reduced to alcohols using:
a) lithium aluminium hydride (LiAlH
4)
b) sodium borohydride (NaBH
4)
c) catalytic hydrogenation
H
+
= diluted acid such as H
2SO
4
RCR'
O
-
H
RCR'
OH
H
H
+
2
o
alcohol
RCR'
O
LiAlH
4 or NaBH
4 or H
2, Ni
ketone CH
3CCH
3
O
-
H
H
+
2-propanol
CH
3CCH
3
O
H
2/Ni
propanone
CH
3CCH
3
OH
H
Example:


3.1 Reduction to Secondary Alcohols

19. C
O
R R'HCN
C
O
CH
3 CH
3HCN
CR R'
OH
CN
CCH
3 CH
3
OH
CN
ketone
cyanohydrin
example
propanone
2-hydroxy-2-methylpropanenitrile * Cyanohydrin may be formed using liquid HCN with a
catalytic amount of sodium cyanide or potassium cyanide.

3.2a Nucleophilic addition of hydrogen cyanide

20. C
O
R R'HCN
C
O
CH
3 CH
2CH
3HCN
CR CN
OH
R'
CCH
3 CN
OH
CH
2CH
3
ketone
cyanohydrin
example
propan-2-one
H
2O/H
+
CR COOH
OH
R
a-hydroxyacid
NH
4
+
H
2O/H
+
CCH
3 COOH
OH
CH
2CH
3
NH
4
+
' Cyanohydrin can be hydrolysed to give α-hydroxyacids.
The nitrile (-CN) group is converted to the –COOH group by
reflux the cyanohydrin with dilute sulphuric acid (H
2O/H
+
) or
concentrated HCl.


3.2a Nucleophilic addition of hydrogen cyanide

21. When shaken with an aqueous of sodium bisulphite, most
aldehydes and ketones formed carbonyl bisulphite (a
colourless crystal).
The reaction takes place more readily with aldehydes than
with ketones.
The nucleophile is the hydrogensulphite ion, HSO
3
-
Example: NaHSO
3 C
O
CH
3 C
OH
CH
3
OSO
2
-
Na
+
Bisulphite salts

3.2b Nucleophilic addition of sodium bisulphite
(NaHSO
3)

22. Aldehydes and ketones condense with ammonia derivatives such as
hydroxylamine and substituted hydrazines to give imine derivatives.
i) Reaction with hydrazine:
Hydrazines derivatives reacts with aldehydes or ketones to form
hydrazones. RC
O
R' H
2N-NH
2 RC
N
R'
NH
2
H
+
H
2O
aldehyde or ketonehydrazine
hydrazone derivative
Example:
C
O
H
2N-NH
2
H
+
hydrazine
H
2O
propanone
propanone hydrazone
H
3C CH
3
C
NNH
2
H
3C CH
3

3.3 Condensation with hydrazines, hydroxlamine,
phenylhydrazine and 2,4-dinitrophenylhydrazine

23. ii) Reaction with hydroxylamine:
Hydroxylamine reacts with ketones and aldehydes to form
oximes. RC
O
R' H
2N-OH
RC
N
R'
OH
H
+
H
2O
aldehyde or ketonehydroxylamine
oxime
Example:
H
2N-OH
H
+
hydroxylamine
H
2O
phenyl-2-propanone
phenyl-2-propanone oxime
O
N
OH

3.3 Condensation with hydrazines, hydroxlamine,
phenylhydrazine and 2,4-dinitrophenylhydrazine

24. iii) Reaction with phenylhydrazine:
RC
O
R'
RC
N
R'
NH-Ph
H
+
H
2O
aldehyde or ketonephenylhydrazine
phenylhydrazone
Example:
H
+
H
2O
penta-2-one
penta-2-one phenylhydrazone
HNNH
H
Ph
phenylhydrazine
HNNH
H
Ph
O N-NH-Ph

3.3 Condensation with hydrazines, hydroxlamine,
phenylhydrazine and 2,4-dinitrophenylhydrazine

25. NO
2
NO
2NH
2N
H
NO
2
NO
2NN
H
C
CH
3
H
2O
room
temperature
butan-2-one 2,4-dinitrophenylhydrazone
butan-2-one 2,4-dinitrophenylhydrazine
CO
NO
2
NO
2NH
2N
H
NO
2
NO
2NN
H
CR'
R
H
2O
room
temperature
2,4-dinitrophenylhydrazine
R
R'
2,4-dinitrophenylhydrazone
(yellow-orange precipitate)
aldehyde or ketone
Example:
CH
3CCH
2CH
3
O
CH
3CH
2 iv) Reaction with 2,4-dinitrophenylhydrazine:


3.3 Condensation with hydrazines, hydroxlamine,
phenylhydrazine and 2,4-dinitrophenylhydrazine

26. A Grignard reagent (a strong nucleophile resembling a
carbanion, R:
-
attacks the electrophilic carbonyl carbon atom to
give an alkoxide intermediate.
Subsequent protonation gives an alcohol. MgBrCH
3CH
2
CO
H
3C
H
3C
CO
- +
MgBr
CH
3
CH
3
CH
3CH
2
COH
CH
3
CH
3
CH
3CH
2
H
3O
+
2-methyl-2-butanol
alkoxideacetoneethylmagnesium bromide


3.4 Reaction with Grignard Reagent

27. IODOFORM TEST

- Reagent: solution of I
2 in an alkaline medium such as NaOH
or KOH.
- Iodoform test is useful for the methyl ketone group
(CH
3C=O) in ketones.

- when ketones containing methyl ketone group is warmed
with iodoform reagent, a yellow precipitate of
triiodomethane (iodoform) is formed.
The overall reaction is
RC
O
CH
3 3I
2
heat
NaOH RC
O
O
-
Na
+
CHI
33HI
salts iodoform
(yellow precipitate)


3.5 Haloform Reaction

28. TESTS ALDEHYDES KETONES
Tollens’ Test / silver mirror test
Reagent and condition:
- ammoniacal silver nitrate
solution ([Ag(NH
3)
2]
+
)
Observation:
Formation of silver mirror
Observation:
Silver mirror did not formed
* Ketones do not react with
Tollens’ reagent
Fehling’s test / Benedict’s test
Reagent and condition:
-Solution of Cu
2+
(aq) ions in an
alkaline solution of sodium
potassium tartate.

*Can be used to distinguish
between:
i)Aldehydes and ketones
ii)Aliphatic aldehydes and
benzaldehyde
Observation;
Blue colour of the Fehling’s
solution dissappears and
brick-red precipitate is
obtained
* Except benzaldehyde
Observation:
Blue colour remains.
* Ketones do not react with
Fehling’s/Benedict’s reagent
Schiff’s test
Reagent and condition:
- Schiff’s reagent

Observation:
Formation of magenta-pink
colour (simple aldehydes)
* Except benzaldehyde and
a few aromatic aldehydes)
Observation:
Ketones (except propanone)
do not react with Schiff’s
reagent.


Tests to Distinguish Aldehydes and Ketones, and Aliphatic Aldehydes and
Aromatic Aldehydes

29. Thank you!

30. CHM 301
Chapter 1 : Alcohol

31. Question
a.A compound , J (C
4H
10O), has three isomers K,L
and M. K is 2-methyl-1-propanol and L is 2-
methyl-2-propanol.

i) Draw the structural formulae of K and L
ii) Describe how you would prepare K using
Grignard reagent
iii) Draw structural formula of M and name it.

b. Compare and provide justification for the acidity
of phenol, ethanol and water.