Aldehydes and Ketones
- Both aldehydes and ketones contain carbonyl group C=O.
- The difference between aldehyde and ketone was found to
be:
•In aldehyde C=O attach with H and R
i.e
R
• In ketone C=O attach with two R
C
R
O
General formulae of aldehyde and ketones
Nomenclature of Aldehydes and Ketones
I) IUPAC:
A) Aldehyde
al ‫ بمقطع‬alkane ‫ في‬e ‫ باستبدال حرف‬alkane ‫ يتم ذكر أسم‬-1
e.g. Methane
Ethane
Methanal
Ethanal
‫‪ - 2‬ألن مجموعة ‪ CHO‬توجد غالبا في طرف السلسلة فال يذكر رقمها‬
‫‪ -3‬في حالة وجود فروع يتم ترقيم السلسلة بإعطاء مجموعة األلدهيد بالرقم ‪1‬‬
‫‪Examples:‬‬
‫‪CH3‬‬
‫‪H3C C CHO‬‬
‫‪CH3‬‬
‫‪2,2-Dimethylpropanal‬‬
‫‪CH3‬‬
‫‪H3C C CH2CHO‬‬
‫‪H‬‬
‫‪3-methylbutanal‬‬
‫‪CH3CH2CH2CHO‬‬
‫‪CH3CHO‬‬
‫‪butanal‬‬
‫‪Ethanal‬‬
‫‪ -4‬ي حالة احتواء السلسلة علي‬
‫يتم ذكر أسم ‪ alkene‬باستبدال حرف ‪ e‬في ‪ alkene‬بمقطع ‪al‬‬
‫ فى حالة احتواء السلسلة علي‬-5
al ‫ بمقطع‬alkyne ‫ في‬e ‫ باستبدال حرف‬alkyne ‫يتم ذكر أسم‬
Examples:
H3C CH CH CHO
H3C C C CHO
2-Butenal
2-butynal
2) Common name
aldehyde ‫ و استبداله ب‬oic ‫ تتم بذكر اسم الحمض محذوفا منه مقطع‬
Examples ;
COOH
Acid
HCOOH
H3C COOH
CH3CH2CH2 COOH
formic acid
acetic acid
butyric acid
benzoic acid
Aldehyde
HCHO
Formaldehyde
H3C CHO
CH3CH2CH2 CHO
acetaldehyde
butyraldehyde
CHO
benzaldehyde
B) Iupac nomenclature of ketones
one ‫ بمقطع‬alkane ‫ في‬e ‫ باستبدال حرف‬alkane ‫يتم ذكر أسم‬.1
Example: Propane
Propanone
‫ أقل ترقيم‬C=O ‫ يتم ترقيم السلسة من الطرف الذي يعطي ل‬- 2
H3C
O
C
CH2CH3
2-butanone
CH3
O
H3C C CH2 C CH3
Br
4-bromo-4-methyl-2-pentanone
Common system of ketones:
.‫ في النهاية‬ketone ‫ ثم نكتب كلمة‬C=O ‫ حول‬alkyl ‫نذكر أسماء‬-
O
H3C C CH2CH3
Ethyl methyl ketone
CH3 O
H3C C CH2 C CH3
H
Isobutyl methyl ketone
O
CH2 C CH3
Benzyl methyl ketone
‫بعض األسماء التي يجب حفظها‬
O
H3C C CH3
O
H3C C Ph
O
Ph C Ph
Acetone
acetophenone
benzophenone
CHO
CH=CH CHO
OH
Salicylaldehyde
Cinnamaldehyde
- Preparation of aldehydes & ketones:
(1) From acid chloride:
This method is called Rosemund reduction..‫ إلى كحول‬ald. ‫ وال يختزل‬ald. ‫ انه يوقف االختزال عند مرحلة‬Pd-BaSO4 catalyst ‫ فائدة‬:‫ملحوظة‬
(2) From geminal dihalide: ‫أي ذرتي هالوجين على نفس ذرة الكربون‬
e.g.
CH3
Cl
C CH3
Cl
2HOH
CH3
OH
C CH3
OH
-2H2O
CH3
O
C CH3
Question: convert toluene to benzaldehyde
Answer
CH3
CH2Cl
Cl2
hv
toluene
OH
HCOH
CHCl2
Cl2
KOH
CHO
-H2O
hv
Benzyl chloride
Benzal chloride
benzaldehyde
(3) Partial decarboxylation of salt of acids:
R
O
C

O
Ca
(RCOO)2Ca
R
C
O
R
O
C
R
- CaCO3
O
Question: Show how could you prepare the following
O
H C H
O
H3C C CH3
O
Ph C Ph
formaldehyde
Acetone
benzophenone
To prepare
R
O
C
O
H C O
by above method, we use two molecules
O
R C O
Ca
H C O
O
H
+

Ca
R C O
O
- 2CaCO3
O
2 R C H
Question: Show how could you prepare the following
H3C
O
C
H
H3C
acetaldehyde
O
C
Ph
acetophenone
‫الطريقة السابقة تستخدم لتحويل األحماض إلي الدهيد أو كيتون كاألتي‬
2 R COOH
Ca(OH)2
Example conversion of
H3C
(RCOO)2Ca
COOH
acetic acid

O
R C R
H3C
O
C
CH3
acetone
(4) From nitrile:
a- Aldehyde:
4R
C N + LiAlH4
H2O
(RCH=N)4LiAl
RCHO
b- Ketone
4R
C N
 
+
R

MgX

R C N MgX
R
H2O
R C NH
R
H2O
HCl
O
R C R + NH4Cl
Methods have been studied :
(5) Oxidation of alcohols:
a- Aldehyde: From oxidation of primary alcohol.
R
CH2OH
Cu,  or
K2Cr 2O7 / H2SO4
O
R CH
b- Ketone: From oxidation of secondary alcohol.
OH
R CH R
Cu,  or KMnO4
or K 2Cr 2O7 / H2SO4
O
R C R
(6) Ozonolysis of alkene :
R
R CH C
R
O3
R
O
R
O
O
R
H2O
Zn
O
O
R CH + R C R
(7) Hydration of alkyne :
HC CH + H2O
H2SO4
HgSO4
H2C CH
OH
CH3
O
CH
Only other alkyne except acetylene will give ketone
R C
CH + H2O
H2SO4
HgSO4
OH
R C=CH2
O
R C CH3
Synthesis of aromatic ketones via Friedel-Crafts acylation:
E.g. Acetophenone
COCH3
CH3COCl
AlCl3
For benzophenone
O
C Cl
+
AlCl3
benzoyl chloride
O
C
Benzophenone
Synthesis of benzaldehyde
a)Gattermann-Koch aldehyde synthesis
CHO
+
CO
+
HCl
AlCl3
benzene
benzaldehyde
b) Gattermann aldehyde synthesis
CHO
+ HCN + HCl
benzene
AlCl3
benzaldehyde
Chemical reactions of aldehydes & Ketones
A-Type I of reaction (Addition reaction)
O
C
H
OH
C
Y
Y
C ‫ وباقي المركب ل‬O ‫ لذرة‬H ‫تعتمد هذه التفاعالت علي إضافة‬
-Examples of this addition is addition of HCN, H2, RMgX, HOH, NaSO3H
H2/Pt
Or LiAlH4 Or
NaBH4
Reduction (Addition of H2)
CH3CH2OH
ethanol
OH
H3C CH CN
Acetaldehyde cyanohydrin
HCN
O
H3C CH
RMgX
OMgX
H3C CH R
(Addition of HCN)
HOH
OH
H3C CH R
(Addition of Grignard)
acetaldehyde
NaSO3H
OH
H3C CH SO3Na
(Addition of Sod. Bisulphite)
Acetaldehyde bisulphite
HOH
OH
H3C CH OH
unstable
-H2O
O
H3C CH
Some observations
.cyanohydrin ‫ متبوعا ً بـ‬ketone ‫ أو‬aldehyde ‫ بذكر اسم‬HCN ‫ يسمى ناتج إضافة‬
‫ كاألتي‬HCN ‫يمكن شرح ميكانيكية إضافة‬
H+CN
H3C
O
H
acetaldehyde
H3C O
C
H CN
H+
H3C OH
C
H CN
Acetaldehyde cyanohydrin
.bisulphite ‫ متبوعا ً بـ‬ketone ‫ أو‬aldehyde ‫ بذكر اسم‬NaSO3H ‫ يسمى ناتج إضافة‬
)
O
R C CH3

( methyl Ketones ‫ أو‬Aldehydes ‫ تتم فقط علي‬NaSO3H ‫ إضافة‬
E.g. these ketones does not add NaSO3H
O
H3CH2C C CH2CH3
O
Ph C CH2CH3
O
Ph C Ph
‫ ثابتة مثل‬H2O ‫األصلي و لكن يوجد بعض اتج إضافة‬Aldehyde ‫ ثانية مكونا‬H2O ‫ غير ثابت و يفقد‬H2O ‫ناتج إضافة‬
O
Cl3C C H
Chloarl
H2O
OH
Cl3C C OH
H
Chloarl hydrate
Special cases of addition reactions
a)Benzoin condensation
2 Ph CHO
Benzaldehyde
alc.
KCN
OH O
Ph CH C Ph
[O]
O
Ph C
Benzoin
O
C Ph
Benzil
KOH
OH
Ph C COOH
Ph
Benzilic acid
b) Formation of hemiacetals and acetals
O
R CH
CH3OH
OH
R CH OCH3
CH3OH
Hemiacetal
O
R C R
CH3OH
OH
R C
R
OCH3
HemiKetal
OCH3
R CH OCH3
Acetal
CH3OH
OCH3
R C
OCH3
R
Ketal
B-Type II of reaction [addition reaction followed by loss of H2O]
e.g. (Condensation with amines)
H2O ‫ باإلضافة العادية متبوعة بفقد‬amines‫يتفاعل مع‬Ald. Or Ketones ‫ أي‬
O
Examples:
H2N X
OH
C NH X
- H2O
N X
NH3
NH2NH2
Hydrazine
NH2NHPh
O
H3C C CH3
Acetone
Phenyl
hydrazine
OH
H3C C CH3
NH2
-H2O
OH
H3C C CH3
NHNH2
-H2O
NH
H3C C CH3
[Addition of amonia]
Acetone imine
N NH2
H3C C CH3
Acetone hydrazone
N NHPh
OH
-H2O
H3C C CH3
H3C C CH3
Acetone pheyl hydrazone
NHNHPh
OH
H3C C CH3
NH2OH
NHOH
Hydroxyl amine
NH2NHCONH2
Semicarbazide
-H2O
OH
H3C C CH3
NHNHCONH2
N OH
H3C C CH3
Formation
of
Hydrazone
[Formation of Oxime]
Acetone oxime
-H2O
N NHCONH2
H3C C CH3
Acetone semicarbazone
[Formation of Semicarbazone]
C-Type III of reaction (Base catalyzed reaction)
1- Aldol condensation:
- It occurs between two aldehydes or two ketones containing α-Hydrogen..
OH
NaOH
2 CH3CHO
H3C CH CH2CHO
-H2O
Aldol product
H3C C CHCHO
H
Crotonaldehyde
Mechanism:
CH3CHO
O
H3C CH +
OH
-H+
CH2CHO
CH2CHO
O
H3C CH CH2CHO
HOH
OH
H3C CH CH2CHO
- Other example:
2 CH3
O
C CH3
OH
CH3
OH
C CH2COCH3
CH3

-H2O
O
C CH C CH3
CH2
CH3
mesityl oxide
Mechanism:
CH3
CH3
O
C
O
C
OH
-H+
CH3
CH2
O
C
CH3
O
CH2
+
 C
CH3
CH3
CH3
O
C
CH2
O
C CH3
CH3
H2O
CH3
O
C
CH2
OH
C CH3
CH3

CH3
O
C
CH3
CH
C
CH3
In case of mixture of acetaldehyde and acetone , we obtain four products
O
H3C CH
+
O
H3C C CH3
Acetone
acetaldehyde
HO
H3C CH CH CHO
Crotonaldehyde
+
O
+ H3C CH CH C CH3
pent-3-en-2-one
CH3
H3C C
CH CHO
+
CH3
O
H3C C
CH C CH3
3-methylbut-2-enal
Mestyl oxide
Mechanism of formation of crotanaldehyde
-
CH3CHO
CH2CHO +
OH
-H+
CH3
CH2CHO
O C H
+
CH3
O
CH CH2CHO
H2O
CH3 CH CHCHO
CH3
OH
CH CH2CHO

-H2O
Mechanism of formation of Mestyl oxide
O
CH3 C
O
CH3 C
OH
-H+
CH3
CH2
O
C
CH3
O
CH2
+
 C
O
CH3 C
CH3
CH3
CH2
O
C CH3
CH3
H2O
CH3
O
C
CH2
OH
C CH3
CH3

CH3
O
C
CH3
CH
C
CH3
Mechanism of formation of 3-methyl-2-butenal
H3C CHO
HO
OH
H3C C CH2CHO
CH3
O
H3C C CH3
H2C CHO
-HOH
H3C C CH CHO
CH3
3-methylbut-2-enal
O
H3C C CH2CHO
CH3
HOH
Mechanism of formation of 3-penten-2-one
O
H3C C CH3
HO
O
H3C C CH2
O H OH
HOH H C C C2 C CH
3
3
H
-HOH
O
H C CH3
O H O
2
H3C C C C CH3
H
O
CH CH3
H3C C C
H
pent-3-en-2-one
2- Cannizaro reaction:
- It occurs between two aldehydes with no α-hydrogen in presence of base to
give an alc. and an acid.
CHO
2
COONa
NaOH
benzaldehyde
CH2OH
+
sodium benzoate
Benzyl alc.
Question: Show the effect of NaOH on acetaldehyde and benzaldehyde
3- Clasien condensation ;
OH
CH CH2CHO
CHO
+ CH3CHO
NaOH
HC
CHCHO
-H2O
Cinnamaldehyde
4- Perkin condensation:
CHO
HC
+ (CH3CO)2O
CH COOH
CH3COONa
Acetic anhydride
+ CH3COOH
Cinnamic acid
D-Type IV of reaction (Different types of reaction)
Oxidation of aldehyde ketones:
R CHO
[O] by
KMnO4 or K 2Cr 2O7
R COOH
aldehyde
acid
Aldehydes can also oxidized by Tollens reagent [Ag(NH3)2OH].
R CHO
+ 2Ag(NH3)2OH
R COOH + 2Ag + 4 NH3 + 2H2O
Tollens
 Ketones are difficult for oxidation
O
H3C C CH3
Acetone
K2Cr2O7
H2SO4
O
H3C C OH
acetic acid
+ HCOOH
Haloform reaction:
- It occurs with aldehyde or ketones containing
O
H3C C
-The only aldehyde gives Iodoform reaction is acetaldehyde
-Methyl ketones (
O
H3C C R
O
H3C C CH3
Acetone
) only
H3C
O
C
H
can give iodoform only for example
O
H3C C Ph
O
H3C C CH2CH3
acetophenone
butan-2-one
O
-These ketones cannot give iodoform because they do not have H C C R
3
H3CH2C
O
C
CH2CH3
pentan-3-one
Ph
O
C
Ph
benzophenone
Examples of iodoform equation :
e.g. CH3
O
C H + NaOH + I2
CHI3 +
O
H C ONa
Iodoform
CH3
O
C CH3 +
NaOI
Sod. formate
CHI3 + CH3
O
C ONa
Mechanism:
O
(1) H3C C CH3 + 3I2
O
I3C C CH3 + 3HI
Halogenation
O
(2) I3C C CH3 + NaOH
CHI3 + CH3COONa
Cleavage
.‫ إلى حمض مع فقد ذرة كربون واحدة‬ketone ‫ او‬ald. ‫ يعتبر تفاعل الهالوفورم أكسدة لـ‬:‫ملحوظة‬
Reduction of aldehydes & Ketones:
1- Reduction by catalytic hydrogen:
It converts aldehyde or ketone to alcohol.
RCHO + H2
Pt
1o alc.
ald.
O
R C R + H2
RCH2OH
Ni or
Pt
OH
R CH R
•2- Reduction to hydrocarbon:
.alkane ‫ إلى‬ketone ‫ او‬ald. ‫• أي تحويل‬
O
C
CH2
For examples;
H3C
O
C
H
acetaldehyde
H3C
O
C
CH3
H3C
CH3
ethane
H3C
CH2CH3
propane
acetone
O
CH3
CH2CH3
acetophenone
ethylbenzene
a- Clemmensen reduction:
O
CH3 C CH3
Zn-Hg
HCl
CH3CH2CH3
b- Walf-Kishner reduction:
O
CH3 C CH3 + H2N NH2
H3C
C N.NH2
H3C
acetone hydrazine
KOH

- N2
CH3CH2CH3
3- Reduction with sod. Borohydride (NaBH4):
CH3 CH
CH CHO
NaBH4
CH3 CH
CH CH2OH
4- Reduction with Mg:
Mg
O
2 CH3 C CH3
O
Mg
CH3
O
CH3
CH3
CH3
H2O
OH OH
CH3 C C CH3
CH3CH3
pinacole
Replacement of oxygen by halogen:
Cl
C
Cl
PCl3, PCl5 or SOCl2 convert C=O into
Example:
H3C
O
C
CH3
PCl5
H3C
propan-2-one
Cl
C CH3
Cl
+ POCl3
2,2-dichloropropane
PCl3, PCl5 or SOCl2 convert –OH to -Cl
R OH
R OH
3 R OH
PCl5
R Cl
SOCl2
PCl3
+ HCl + POCl3
R Cl + HCl + SO2
3 R Cl + H3PO3
R COOH
R COOH
3 R COOH
PCl5
SOCl2
PCl3
O
R C Cl + HCl + POCl3
O
R C Cl
+ HCl + SO2
O
3 R C Cl + H3PO3
The reaction of aldehyde or ketones with PCl3, PCl5 or SOCl2, can be
used to convert aldehyde or ketones alkyne as follow
e.g. conversion of acetone to propyne
O
H3C C CH3
Cl
H3C C CH3
Cl
PCl5
propan-2-one
alc. KOH
H3C C CH
-2 HCl
propyne
2,2-dichloropropane
Halogenation of α-carbon:
O
CH3 C CH3
Br2
acid or base
O
CH3 C CH2Br
O
CH3 C CH2 CH3 + X2
X = Cl, Br, I
Br2
Br
O
CH3 C CH
Br
O
CH3 C CH CH3
X
- In case of aromatic aldehyde or ketones.
a) In absence of Fe or FeCl3 catalyst
 In this case the reaction occur at α-carbon to C=O or in H of CHO
O
C
CHO
Cl
Cl2
benzaldehyde
O
C
benzoyl chloride
CH3
Cl2
O
C
CH2Cl
acetophenone
2-chloro-1-phenylethanone
b) In absence of Fe or FeCl3 catalyst
Aldehydes and ketones are m- directing group, so orient halogen in m- position
Polymerization reaction
Only aldehydes can polymerize
Examples
a) Polymerization of formaldehyde in presence of water
H2O
HOH2C OCH2
OCH2OH
n
Paraformaldehyde
nCH2O
formaldehyde
B )Polymerization of formaldehyde and acetaldehyd of presence of H2SO4
H2SO4
3CH2O
O
O
O
formaldehyde
Sym-trioxane
CH3
3
H3C
O
CH
acetaldehyde
H2SO4
O
H3C
O
O
CH3
Paraldehyde
3CH2O
H2SO4
O
O
O
formaldehyde
Sym-trioxane
CH3
O
3 H3C CH
acetaldehyde
H2SO4
O
H3C
O
O
CH3
Paraldehyde