aldehydes and ketones - both aldehydes and ketones contain carbonyl group c=o. - the difference...
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Aldehydes and KetonesAldehydes and Ketones
- Both aldehydes and ketones contain carbonyl group C=O.
-The difference between aldehyde and ketone was found to be:
C OR
R
•In aldehyde C=O attach with H and R i.e
• In ketone C=O attach with two R
General formulae of aldehyde and ketones
Nomenclature of Aldehydes and Ketones
I) IUPAC:
A) Aldehyde
أسم- 1 ذكر حرف alkaneيتم alبمقطع alkaneفي eباستبدال
e.g. Methane Methanal
Ethane Ethanal
مجموعة - 2 رقمها CHOألن يذكر فال السلسلة طرف في غالبا توجد
األلدهيد - 3 مجموعة بإعطاء السلسلة ترقيم يتم فروع وجود حالة في1بالرقم
Examples:
CH3CHO
Ethanal
CH3CH2CH2CHO
butanal
H3C CH
CH3
CH2CHO
3-methylbutanal
H3C C
CH3
CHO
CH3
2,2-Dimethylpropanal
السلسلة- 4 احتواء حالة ي علي
أسم ذكر حرف alkene يتم al بمقطع alkeneفي eباستبدال
علي- 5 السلسلة احتواء حالة فى
أسم ذكر حرف alkyneيتم alkyneفي eباستبدالalبمقطع
Examples:
H3C CH CH CHO
2-Butenal
H3C C C CHO
2-butynal
2) Common name
مقطع منه محذوفا الحمض اسم بذكر و oicتتمب aldehydeاستبداله
Examples ;
HCOOH
formic acid
HCHO
Formaldehyde
H3C COOH
acetic acid
H3C CHO
acetaldehyde
CH3CH2CH2 COOH
butyric acid
CH3CH2CH2 CHO
butyraldehyde
COOH
benzoic acid
CHO
benzaldehyde
Acid
Aldehyde
H3C C
O
CH2CH3
2-butanone
H3C C
CH3
Br
CH2 C
O
CH3
4-bromo-4-methyl-2-pentanone
B) Iupac nomenclature of ketonesB) Iupac nomenclature of ketones
أسم 1. ذكر حرف alkaneيتم oneبمقطع alkaneفي eباستبدال
Example: Propane Propanone
ل - 2 يعطي الذي الطرف من السلسة ترقيم أقل C=Oيتمترقيم
Common system of ketones:
أسماء - كلمة C=Oحول alkylنذكر نكتب في ketoneثم.النهاية
H3C C
O
CH2CH3 H3C CH
CH3
CH2 C
O
CH3
Ethyl methyl ketone Isobutyl methyl ketone
CH2 C
O
CH3
Benzyl methyl ketone
حفظها يجب التي األسماء بعض
H3C C
O
CH3
Acetone
H3C C
O
Ph
acetophenone
Ph C
O
Ph
benzophenone
CHO
OH
Salicylaldehyde
CH=CH CHO
Cinnamaldehyde
- Preparation of aldehydes & ketones:
(1) From acid chloride:
-This method is called Rosemund reduction.
مرحلة Pd-BaSO4 catalystفائدة : ملحوظة عند االختزال يوقف يختزل .aldانه والald. كحول .إلى
(2) From geminal dihalide: ذرة نفس على هالوجين ذرتي ذرة أي نفس على هالوجين ذرتي أيالكربون الكربون
Question: convert toluene to benzaldehyde
Answer
CH3 C CH3
Cl
Cl
2HOH CH3 C CH3
OH
OH
-2H2OCH3 C CH3
Oe.g.
CH3
Cl2hv
toluene
CH2Cl
Benzyl chloride
Cl2hv
CHCl2
Benzal chloride
KOH
HC
OH
OH
-H2O
CHO
benzaldehyde
R C
O
O
R C
O
OCa
- CaCO3
R C
O
R(RCOO)2Ca
Question: Show how could you prepare the following
H C
O
H H3C C
O
CH3 Ph C
O
Ph
formaldehyde benzophenoneAcetone
To prepareR C
O
H
(3) Partial decarboxylation of salt of acids:
by above method, we use two molecules
R C
O
O
R C
O
OCa
- 2CaCO3
R C
O
HH C
O
O
H C
O
OCa + 2
الدهيد إلي األحماض لتحويل تستخدم السابقة كاألتي الطريقة كيتون أو
R COOH2Ca(OH)2 (RCOO)2Ca R C
O
R
Example conversion of H3C COOH H3C C
O
CH3
acetic acid acetone
Question: Show how could you prepare the following
H3C C
O
H H3C C
O
Ph
acetaldehyde acetophenone
(4) From nitrile:
a- Aldehyde:
H2OR C N +4 LiAlH4 (RCH=N)4LiAl RCHO
b- Ketone
H2OR C N +4 R MgX
HClH2O
CR
R
N MgX CR
R
NH
R C R
O
NH4Cl+
Methods have been studied:
(5) Oxidation of alcohols:
a- Aldehyde: From oxidation of primary alcohol.
orR CH2OH Cu,
K2Cr2O7 / H2SO4R CH
O
b- Ketone: From oxidation of secondary alcohol.
or Cu, or K2Cr2O7 / H2SO4
R CH R
OHKMnO4 R C R
O
(6) Ozonolysis of alkene :
R CH
O
+R CH CR
RR C R
OO3
O O
O R
RR H2O
Zn
(7) Hydration of alkyne :
+HC CH H2OH2SO4
HgSO4
H2C CH
OHCH3 CH
O
Only other alkyne except acetylene will give ketone
R C CH3
O+C CHR H2O
H2SO4
HgSO4R C=CH2
OH
Synthesis of aromatic ketones via Friedel-Crafts acylation:Synthesis of aromatic ketones via Friedel-Crafts acylation:
E.g. Acetophenone
CH3COCl
AlCl3
COCH3
For benzophenone
C
O
Cl
+AlCl3
benzoyl chloride Benzophenone
C
O
Synthesis of benzaldehydeSynthesis of benzaldehyde
a)a)Gattermann-Koch aldehyde Gattermann-Koch aldehyde synthesissynthesis
benzene
+ CO + HClAlCl3
CHO
benzaldehyde
b) Gattermann aldehyde synthesisb) Gattermann aldehyde synthesis
benzene
+ HCN + HClAlCl3
CHO
benzaldehyde
Chemical reactions of aldehydes & Ketones
A-Type I of reaction (Addition reaction)A-Type I of reaction (Addition reaction)
C
OH Y
C
OH
Y
إضافة علي التفاعالت هذه ل Oلذرة Hتعتمد المركب Cوباقي-Examples of this addition is addition of HCN, H2, RMgX, HOH, NaSO3H
H3C CH
O
H2/Pt
Or LiAlH4 OrNaBH4
HCN
RMgX
CH3CH2OH
H3C CH
OH
CN
Acetaldehyde cyanohydrin
H3C CH
OMgX
RHOH
H3C CH
OH
R
Reduction (Addition of H2)
(Addition of HCN)
(Addition of Grignard)
NaSO3HH3C CH
OH
SO3Na
Acetaldehyde bisulphite
(Addition of Sod. Bisulphite)
HOHH3C CH
OH
OH
unstable
H3C CH
O
acetaldehyde
ethanol
-H2O
Some observations
إضافة ناتج اسم HCNيسمى بـ ketoneأو aldehydeبذكر rمتبوعاcyanohydrin .
إضافة ميكانيكية شرح كاألتي HCNيمكن
OH
H3C
acetaldehyde
H+CN
HC
H3C
CN
O H+
HC
H3C
CN
OH
Acetaldehyde cyanohydrin
إضافة ناتج اسم NaSO3Hيسمى بـ ketoneأو aldehydeبذكر rمتبوعاbisulphite.
إضافةNaSO3H علي فقط ( methyl Ketonesأو Aldehydesتتم
( R C
O
CH3
E.g. these ketones does not add NaSO3H
H3CH2C C
O
CH2CH3 Ph C
O
CH2CH3 Ph C
O
Ph
إضافة يفقد H2Oناتج و ثابت مكونا H2Oغير بعض Aldehydeثانية يوجد لكن و األصليإضافة مثل H2Oاتج ثابتة
Cl3C C
O
H
Chloarl
H2OCl3C C
OH
H
OH
Chloarl hydrate
Special cases of addition reactionsSpecial cases of addition reactions
a)Benzoin condensation
Ph CHO2alc.
KCNPh CH
OH
C
O
Ph
Benzoin
[O]Ph C
O
Ph
BenzilBenzaldehyde
C
O KOHPh C
Ph
OH
COOH
Benzilic acid
b) Formation of hemiacetals and acetals
R CH
OCH3OH
R CH
OH
OCH3
Hemiacetal
CH3OHR CH
OCH3
OCH3Acetal
R C
OCH3OH
R C
OH
OCH3
HemiKetal
CH3OHR C
OCH3
OCH3
Ketal
R
R R
B-Type II of reactionB-Type II of reaction [addition reaction followed by loss of H[addition reaction followed by loss of H22O]O]
e.g. (Condensation with amines)e.g. (Condensation with amines)
أيAld. Or Ketones مع بفقد aminesيتفاعل متبوعة العادية باإلضافةH2O
OH2N X
N X- H2O
C
OH
NH X
Examples:
H3C C
O
CH3
Acetone
NH3
NH2NH2
Hydrazine
NH2NHPh
Phenyl hydrazine
NH2OH
Hydroxyl amine
NH2NHCONH2
Semicarbazide
H3C C
NH
CH3
H3C C
N
CH3
H3C C
N
CH3
H3C C
N
CH3
H3C C
N
CH3
NH2
NHPh
OH
NHCONH2
Acetone imine
Acetone hydrazone
Acetone pheyl hydrazone
Acetone oxime
Acetone semicarbazone
H3C C
OH
CH3
NH2
-H2O
H3C C
OH
CH3
NHNH2
-H2O
H3C C
OH
CH3
NHNHPh
-H2O
H3C C
OH
CH3
NHOH
-H2O
[Addition of amonia]
[Formation of Oxime]
H3C C
OH
CH3
NHNHCONH2
-H2O
[Formation of Semicarbazone]
Formationof Hydrazone
C-Type III of reactionC-Type III of reaction (Base catalyzed reaction)(Base catalyzed reaction)
1- Aldol condensation:1- Aldol condensation:
- It occurs between two aldehydes or two ketones containing α-Hydrogen..
2 CH3CHONaOH
H3C CH CH2CHO
OH
Aldol product
-H2OH3C C
HCHCHO
Crotonaldehyde
Mechanism:
OH
H3C CH CH2CHO
O
CH3CHO CH2CHO-H+
H3C CH
O
+ CH2CHOHOH
H3C CH CH2CHO
OH
- Other example:
COCH32-H2O
CH3 C CH
CH2
C CH3
O
CH3 C CH3
O
2 OH CH3 C CH
OH
CH3
mesityl oxide
Mechanism:
CH3 C CH3
OOH-H+ CH2 C CH3
O
CH3 C
O
CH2 + C CH3
O
CH3
CH3 C
O
CH2 C
O
CH3
CH3H2O
CH3 C
O
CH2 C
OH
CH3
CH3
CH3 C
O
CH CCH3
CH3
In case of mixture of acetaldehyde and acetone , we obtain four products
H3C CH
O
acetaldehyde
+ H3C C
O
CH3
Acetone
HOH3C CH CH CHO
Crotonaldehyde
+ H3C CH CH C
O
CH3
pent-3-en-2-one
+ H3C C CH CHO
CH3
3-methylbut-2-enal
+ H3C C CH
CH3
C
O
CH3
Mestyl oxide
Mechanism of formation of crotanaldehydeMechanism of formation of crotanaldehyde
+
-
-OH -H+CH3CHO CH2CHO
CH2CHO + CH3 C
O
H CH3 CH CH2CHO
OH2O
CH3 CH CH2CHO
OH
-H2O
CH3 CH CHCHO
Mechanism of formation of Mestyl oxideMechanism of formation of Mestyl oxide
CH3 C CH3
OOH-H+ CH2 C CH3
O
CH3 C
O
CH2 + C CH3
O
CH3
CH3 C
O
CH2 C
O
CH3
CH3H2O
CH3 C
O
CH2 C
OH
CH3
CH3
CH3 C
O
CH CCH3
CH3
Mechanism of formation of 3-methyl-2-butenalMechanism of formation of 3-methyl-2-butenal
H3C CHOHO
H2C CHOH3C C
O
CH3H3C C
CH3
O
CH2CHOHOH
H3C C
CH3
OH
CH2CHO-HOH
H3C C
CH3
CH CHO
3-methylbut-2-enal
Mechanism of formation of 3-penten-2-oneMechanism of formation of 3-penten-2-one
H3C C
O
CH3
HOH3C C
O
CH2
H C
O
CH3H3C C
O H2C C
H
O
CH3
HOH H3C C
O H2C C
H
OH
CH3-HOH
H3C C
O
CH
CH CH3
pent-3-en-2-one
2- 2- Cannizaro reaction:Cannizaro reaction:
- It occurs between two aldehydes with no α-hydrogen in presence of base to give an alc. and an acid.
2
CHO
NaOH
COONa
sodium benzoate
+
benzaldehyde
CH2OH
Benzyl alc.
Question: Show the effect of NaOH on acetaldehyde and benzaldehyde
CHO
+ CH3CHONaOH
CH CH2CHO
OH
-H2OHC CHCHO
Cinnamaldehyde
4- Perkin condensation:4- Perkin condensation:
CHO
+ (CH3CO)2OCH3COONa
HC CH
Cinnamic acid
Acetic anhydride
COOH
+ CH3COOH
D-Type IV of reaction (Different types of reaction)
3 -Clasien condensation;
Oxidation of aldehyde ketones:
R CHO [O] byKMnO4 or K2Cr2O7
R COOH
acidaldehyde
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
H3C C
O
CH3
K2Cr2O7
H2SO4H3C C
O
OH
acetic acidAcetone
+ HCOOH
Haloform reaction:Haloform reaction:
- It occurs with aldehyde or ketones containingIt occurs with aldehyde or ketones containing H3C C
O
-The only aldehyde gives Iodoform reaction is acetaldehyde The only aldehyde gives Iodoform reaction is acetaldehyde H3C C
O
H
-Methyl ketones ( H3C C
O
R ) only can give iodoform only for example
H3C C
O
CH3 H3C C
O
Ph H3C C
O
CH2CH3
Acetone acetophenone butan-2-one
-These ketones cannot give iodoform because they do not have H3C C
O
R
H3CH2C C
O
CH2CH3 Ph C
O
Ph
pentan-3-one benzophenone
Examples of iodoform equation :Examples of iodoform equation :
e.g. CH3 C H
O
+ NaOH + I2 + C ONa
O
H
Iodoform Sod. formate
CH3 C CH3
O
+ NaOI C ONa
O
CH3+
CHI3
CHI3
Mechanism:
(1) H3C C
O
CH3 + 3I2 I3C C
O
CH3 + 3HI
I3C C
O
CH3(2) + NaOH CHI3 + CH3COONa
Halogenation
Cleavage
لـ: ملحوظة أكسدة الهالوفورم تفاعل . ketoneاو .aldيعتبر واحدة كربون ذرة فقد مع حمض إلى
Reduction of aldehydes & Ketones:Reduction of aldehydes & Ketones:
1- Reduction by catalytic hydrogen: It converts aldehyde or ketone to alcohol.
R C
O
R +
RCHO + H2Pt
RCH2OHald. 1 alc.o
H2Ni or Pt R CH R
OH
•2- Reduction to hydrocarbon2- Reduction to hydrocarbon::
تحويل • .alkaneإلى ketoneاو . aldأي
C
O
CH2
For examples;
H3C C
O
H
acetaldehyde
H3C CH3
ethane
H3C C
O
CH3
acetone
H3C CH2CH3
propane
CH3
O
acetophenone
CH2CH3
ethylbenzene
a- Clemmensen reduction:
CH3 C CH3
OZn-Hg HCl CH3CH2CH3
b- Walf-Kishner reduction:
+CH3 C CH3
O
CH3CH2CH3NH2H2N CH3C
H3CN.NH2
KOH
acetone hydrazine
- N2
3- Reduction with sod. Borohydride (NaBH4):3- Reduction with sod. Borohydride (NaBH4):
CH3 CH CH CHO NaBH4 CH3 CH CH CH2OH
4- Reduction with Mg:4- Reduction with Mg:
CH3 C CH3
O
2 Mg
O OMg
CH3
CH3CH3
CH3
H2O CH3 C C CH3
OHOH
CH3CH3
pinacole
Replacement of oxygen by halogen:Replacement of oxygen by halogen:
PCl3, PCl5 or SOCl2 convert C=O into C
Cl
Cl
Example:
H3C C
O
CH3
PCl5H3C C CH3
Cl
Cl
+ POCl3
2,2-dichloropropanepropan-2-one
PCl3, PCl5 or SOCl2 convert –OH to -Cl
R OHPCl5
R Cl + HCl + POCl3
R OHSOCl2
R Cl + HCl + SO2
R OHPCl3
3 R Cl3 + H3PO3
R COOHPCl5
R + HCl + POCl3
SOCl2+ HCl + SO2
PCl33 3 + H3PO3
R COOH
R COOH
C
O
Cl
R C
O
Cl
R C
O
Cl
H3C C
O
CH3
PCl5H3C C
Cl
Cl
CH3
2,2-dichloropropane
alc. KOH
-2 HClH3C C CH
propynepropan-2-one
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
Halogenation of α-carbon:
CH3 C CH3
O Br2
acid or base CH3 C CH2Br
OBr2 CH3 C CH
O Br
Br
CH3 C CH2
O
CH3 + X2 CH3 C CH
O
CH3
XX = Cl, Br, I
- In case of aromatic aldehyde or ketones.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
CHO
benzaldehyde
Cl2
C
O
Cl
benzoyl chloride
Cl2
C
O
CH3
acetophenone
C
O
CH2Cl
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 reactionPolymerization reaction
Only aldehydes can polymerizeExamples a) Polymerization of formaldehyde in presence of watera) Polymerization of formaldehyde in presence of water
nCH2Oformaldehyde
H2OHOH2C OCH2 OCH2OH
nParaformaldehyde
B )Polymerization of formaldehyde and acetaldehyd of presence of H2SO4
3CH2OH2SO4 O
O
O
Sym-trioxane
3 H3C CH
OH2SO4
acetaldehyde
O
O
O
H3C CH3
CH3
Paraldehyde
formaldehyde
3CH2OH2SO4 O
O
O
Sym-trioxane
3 H3C CH
OH2SO4
acetaldehyde
O
O
O
H3C CH3
CH3
Paraldehyde
formaldehyde