Organic Chemistry: Carbonyl Compounds and Nitrogen Compounds Discussing nucleophilic addition on carbonyl discussion and reactions on carboxylic acid and its derivates. Also a brief description about amino acids and protein structures

1. Organic Chemistry III
Carbonyl compounds and
Nitrogen Compounds
Indra Yudhipratama

2. Outline
 Carbonyl Compounds
(Aldehydes and Ketones)
 Reduction-oxidation
reactions
 Addition reaction
 Identification Reaction
 Carboxylic Acid and Derivatives
 The Acidity of Carboxylic
acid
 The Formation
 Reaction to form salts, esters,
and acyl chloride
 Nitrogen Compounds
 The basicity of amines
 Amino acids and Proteins

3. Aldehydes and Ketones
 The Formation and the redox of Aldehydes and Ketones
R
R
O
R
O
H
NaBH4
NaBH4
Cr2O7
2-
H+
Cr2O7
2-
H+
Cr2O7
2-
H+
Cr2O7
2-
H+
CH3
O
OH
butanoic acid
No Reaction
CH3 OH
CH3 O
CH3
CH3
OH
CH3
CH3
O

4. Aldehydes and Ketones
 The Nucleophilic Addition
Nucleophile is a chemical that can donate a pair of electron with the
subsequent formation of a covalent bond
Nucloephilic Addition is addition reaction in which the first step is the
attack by a nucleophile on the electron-deficient part of molecule
R
O
R



5. Aldehydes and Ketones
 E.g. Reaction between NaCN in water with butanal
via:
Draw the product of this reaction:

6. Aldehydes and Ketones
 Reaction with 2,4-DNPH (2,4-dinitrophenylhydrazine) – Identification.
 Gives the yellow precipitate of hydrazone.
 To identify the carbonyl groups
2,4-DNPH Hydrazone

7. Aldehydes and Ketones
Another identification test
 Fehling’s Reagent (an alkaline solution of Cu2+ ions
complex)
 Aldehydes: Red precipitate and carboxylic acid forms.
 Ketones: No changing
 Tollen’s Reagent (an aqueous solution of AgNO3 in excess
ammonia)
 Aldehydes: Silver mirror and carboxylic acid forms.
 Ketones: No changing

8. Aldehydes and Ketones
Another identification test
 Acidified Cr2O7
2-
 Aldehydes: The solution turns green (Cr3+)
 Ketones: No changing (solution still yellow-orange)
 An alkaline solution of iodine
 To identify CH3CO- FG

9. Aldehydes and Ketones
(Summary of Identification)
Type of Test Aldehydes Ketones
2,4-DNPH (+) yellow ppt. (+) yellow ppt.
Tollen’s Reagent (+) silver mirror (-) no changing
Fehling’s Reagent (+) red ppt. (-) no changing
Oxidation acidified
Cr2O7
2-
(+) solution turns into
green
(-) no changing
An aqueos alkaline of iodine to identify CH3CO – gives
yellow ppt.

10. Carboxylic Acids
 Main features: Behaves as an acid and has the highest b.p. along all
the functional group.
 The formation of Carboxylic acid
 Oxidation of alcohol
R
OH
O
CH3
O
OH
butanoic acid
CH3 OH
CH3 O
Cr2O7
2-
H+
Cr2O7
2-
H+

11. Carboxylic acids
 Hydrolysis cyanohidrin or nitriles
Via:
Hydrolysis amide (see later)

12. Carboxylic Acids
The Acidity of Carboxylic Acids
 Acidity  How strong the acid is.
 The easiness to release H+ (proton)
 Measures as Ka or pKa [pKa = -log(Ka)]. Higher pKa, weaker the acid
FG substituted carboxylic acid
 e- withdrawing FG (e.g. Cl) stabilise the ion by inductive effects.
 More e- with drawing FG more stable the ion.
 Further the FG, decrease the acidity.
 e- donating FG un-stabilise the ion, so the acidity is decreasing.
CH3
OH
O
+ OH2 O
+
H
H
H
+CH3
O
O
-

13. Carboxylic Acids
(pKa = 4.76) (pKa = 2.86) (pKa = 1.48) (pKa = 0.70)
(pKa = 4.81) (pKa = 2.85) (pKa = 4.05) (pKa = 4.50)
CH3
OH
O
OH
OCl
OH
OCl
Cl OH
OCl
Cl Cl
OH
O
CH3
Cl
OH
O
CH3
Cl
OH
O
Cl
OH
O
CH3

14. Carboxylic Acids
Quick Review:
Predict the order of acidity from the strongest to the weakest from
those acids below. Give your reason.
(1) (2) (3) (4)
Ans:
(1) > (2) > (3) > (4)
F has the highest electronegativity, so it has the biggest inductive effect/the
electrons more attracts toward FG. Thus, the resonance is more stabilised
compare to the others.
OH
O
Cl
OH
O
F
OH
O
Br
OH
O
I
fluoroacetic acid chloroacetic acid bromoacetic acid iodoacetic acid

15. Carboxylic Acids
 The Reactions
 Formation of Salts
 Reacts with an alkaline solution to give salts.
 Reacts with alcohols to form esters
 Reaction with SOCl2 or PCl3 or PCl5 to form acyl chlorides
R
OH
O
+ NaOH R
O
-
O
+ OH2
Na
+

16. Carboxylic Acid Derivatives
 Ester Formation under acidic condition
Via:
 Esters can also be synthesised by reacting acyl chlorides with alcohol.
 Why can’t we make esters under alkaline condition?

17. Carboxylic Acid Derivates
 Quick Quiz
 Predict the results of the reaction below. All reactions are in acidic
condition.

18. Carboxylic Acid Derivates
 Ester hydrolysis with acid catalyst
 Via:

19. Carboxylic Acid Derivates
 Ester hydrolysis in alkaline condition
 Via:
 This process is also called saponification (making soap)

20. Carboxylic acid Derivates
 Mainly, Polyesters can be formed by reacting dicarboxylic acids and
diols
OH
OO
OH
OH
OH
+
benzene-1,4-dicarboxylic acid
ethane-1,2-diol PET

21. Carboxylic Acid Derivates
 Acyl Chloride
 The hydrolysis would give carboxylic acids. Reacts readily with water
R
OH
O R
Cl
O
SOCl2 or PCl3 or
PCl5
R
Cl
O H2O
R
OH
O
OH -
/H
2 O
R
O
-
O

22. Carboxylic Acid Derivates
 The reactions of acyl chloride
 Reacts with alcohols to give esters
 Reacts with primary amines to give amides
 Via:

23. Carboxylic acid derivates
 Reacts with phenol to give esters
 Via:

24. Nitrogen Compounds
 Main Features
 Relatively high b.p. for organic compounds
 High solubility in water and polar solvent
 Act as basic compounds
NH3 NH2 R
NH R
R1
N R
R1
R2ammonia
NH3 NH2 CH3
NH CH3
CH3 N CH3
CH3
CH3
ammonia methanamine N-methylmethanamine N,N-dimethylmethanamine
The Classification
1o 2o 3o
e.g.

25. Nitrogen Compounds
 The formations
 Substitution reaction
 Reduction of nitrile
CH3
Br
NH3 CH3
NH2
CH3
N
LiAlH4
Dry ether
CH3
NH2

26. Nitrogen Compounds
 The reactions
 The formation of Amides from amines and acyl chlorides
 Why amides can’t be formed from reaction of carboxylic acids and
amines?

27. Nitrogen Compounds
 The Hydrolysis in aqueous alkaline solution
 Via:
 Requires stronger (more extreme) condition than hydrolysis of ester

28. Nitrogen Compounds
 The Hydrolysis in aqueous acidic solution
 Via:

29. Nitrogen Compounds
 The formation of Polyamides
It is formed from diacyl chlorides and diamines
Cl
OO
Cl
NH2NH2+

30. 28-4 Proteins

33. Zwitterion
Copyright © 2011 Pearson
Canada Inc.
General Chemistry: Chapter 28Slide 33 of 59

34. Peptides

35. The peptide-bond structures
The character of double
bond at peptide bond
create atoms C, N, H,
O almost co-planar.

36. Protein
 20 different amino acids
polymerise to build protein.
 Protein has unique sequence.
 The sequence of amino acids
that build the protein is
called primary structure.
 Different sequences, provide
different function of protein
Primary structure of
myoglobin

37. From Gene to Protein
(Protein Synthesis in vivo)

38. The Genetic Code

39. Translasi

40. Secondary Structure
Stabilise by hydrogen bonding

41. Tertiary Structure
Two Main structure:
Fibrous and Globular

42. Linkages contributing to tertiary structure of
proteins
FIGURE 28-15

43. The four levels of protein structure
FIGURE 28-16
Copyright © 2011 Pearson
Canada Inc.
General Chemistry: Chapter 28Slide 43 of 59

44. Another example of
quaternary structure:
Nucleosome