1. Carbonyl Compounds

2. Carbonyl compounds C O C O R’ R H Carbonyl group sp2 hybridized carbon
Coplanar  bonds, 120o bond angle
p-p overlap  bond
Two types of compounds
Aldehyde Ketone C O R’ R H

3. Polarity of carbonyl bond
Dipole moment
propan-1-ol 1.69D
propanone 2.88
ethanal 2.72
C+
O-
-bond ve inductive effect
-bond readily polarizable
(mesomeric effect) C+
O:-

4. Chemical reaction C+ O H C OH Br C O H-Br :Br-
No electrophilic additions (why?)

5. Chemical reaction C OH Br No electrophilic additions (why?)
Big +ve,
unstable
product
Energetic Factor
(Unstable)

6. Chemical reaction C+ OH No electrophilic additions (why?) Big +ve Ea ,
unstable
Transition
state
Kinetic Factor
(Unstable) C+ OH

7. Chemical reaction
No nucleophilic substitution C O
Nu-: O- Nu

8. Nucleophilic Addition
H/R’ R C O
Nu -:
H/R’ R E+ C E CN
H/R’ R
Reactivity:
Electrophilicity of C atom
of the C=O group.
Strength of Nu:-
Steric effect at the carbonyl
group

9. Addition of HCN C O H/R’ R + H-CN OH CN
Reactivity: HCHO > CH3CHO > ArCHO > CH3COCH3
> CH3COR > RCOR > ArCOAr

10. Nucleophilic Addition
Addition of HCN (using KCN+H+)
H/R’
H/R’
slow C O R C O-
CN-:
Note:
HCN is NOT
used.
Because
Toxic
Weak acid
little CN- R CN
fast
H/R’
HCN R C OH
Cyanohydrin
(2-hydroxynitrile) CN

11. Usefulness in organic synthesis
H2O,H+
reflux C OH
COOH
H/R’ R C OH CN
H/R’ R
c.H2SO4,heat
-C=C-COOH
(,-unsaturated acid)
+1 carbon (longer carbon
chain)
2 functional group

12. Addition of sodium hydrogensulphate(IV)
C-S bond is formed as S is more nucleophilic than O C O-
SO3H R’ R
Room temp.
Na+ C O R’ R
Na+ HSO3- .. C OH
SO3- Na+ R’ R
Sodium hydrogensulphate(IV) adduct, isolated as colourless crystals

13. Addition of sodium hydrogensulphate(IV)
Limit to aliphatic aldehydes and sterically
unhindered ketones (steric effect)
% product from 1mol NaHSO3 in 1 hour:
C=O
CH3 H
89%
C=O
CH3
56%
C=O
CH3
C2H5
36% =O
35%
C=O
(CH3)2CH
CH3
12%
C=O
(CH3)3C
CH3 6%
C=O
C2H5 2%
C=O Ph
CH3 1%

14. Addition of sodium hydrogensulphate(IV)
Reversible (can be reversed by aq. Alkali or
acid by shifting eqm. position to LHS by
HSO3- + H+=> SO2 , HSO3- + OH- => SO32-)
Use to purify liquid or gaseous carbonyl
compounds which are difficult to purify
by direct recrystallization.

15. Addition-elimination (condensation)R’ R N: HO H
(Hydroxylamine) HO N+ C O- H R’ R HO N C OH H R’ R
-H2O HO N C R’ R
(Oxime)

16. Addition-eliminationC O R’ R
NH-N=C ..
NO2
2,4-dinitrophenylhydrazone
(yellow or light orange crystals) R’ R
NH-NH2 ..
NO2
2,4-dinitrophenylhydrazine
(Brady’s reagent)

17. Phenylhydrazone Products have sharp and characteristic melting point.
Used as the identification of the original
aldehyde and ketone
Note:
NH3 does not react
Predict the product obtained by
adding H2N-NH2 to propanal.

18. Oxidation KMnO4/H+ , K2Cr2O7/H+ (Strong oxidizing agent)
RCHO => RCOOH
RCH2COCH2R’ => RCOOH + R’ CH2COOH +
RCH2COOH + R’COOH
C6H5CHO => C6H5COOH requiring reflux for hours

19. Oxidation Tollen’s reagent (silver mirror test)
Reagent: 2Ag+ + 2OH- => Ag2O + H2O
Ag2O + 4NH3 + H2O => 2Ag(NH3)2OH
2[Ag(NH3)2]+ + RCHO + 3OH-
=> RCOO- +2H2O + 4NH3 + 2Ag (mirror)
No reaction with ketone
(Tollen’s reagent is a mild O.A.)

20. Oxidation Fehling’s reagent
Reagent: alkaline solution of copper(II) tartrate
RCHO + 2Cu2+ + 5OH- => RCOO- + 3H2O + Cu2O
(Fehling) (brick-red)
Note: No reaction with Ketones and Aromatic Aldehydes

21. Reduction Reducing agent: LiAlH4 Lithium Tetrahydridoaluminate
NaBH4 Sodium Tetrahydridoborate
Both equivalent to a source of hydride ion, H-. R C O
H/R R O- C
H/R H R OH C
H/R H H+ H-

22. Reduction LiAlH4 must be kept dry i.e. in solution of dry ether
LiBH4 is less powerful,
can be used in aqueous solution.
Reducing agent: H2/Ni, similar to alkene R C O
H/R
H2/Ni
RCH2OH

23. Tri-iodomethane reaction
CH3 C O
H/R
OH-
-H2O
-CH2 X2
CH2X
-X-
CX3 HO O-
CX3- + R/HCOOH
CHX3 + RCOO-
(RCOCH3 + I2/OH- => RCOO- + CHI3 ,yellow ppt.)