Synthesis and reactions

1. SYNTHESIS AND
REACTIONS OF
DIAZINES
 Presented to:- Prof. Kamal Kishore
Presented by:- Manish Kumar
M.Sc. Chemistry(3rd sem)
Roll no. 4587
Practical paper code- 516
Date-5 Feb, 2021

2. Introduction
 Diazines are the group of organic compound having molecular
formula C4H4N2.
 It contains a benzene ring in which two of the C-H fragments have
replaced by isolobal Nitrogen.
 Types:
 Nucleophilic attack on the ring carbon is easier than electrophilic
attack due to two Nitrogen present on the ring which decrease the
energy of p- molecular orbitals.
 Also weaker bases than Pyridine.
N
N
N
N
N
N
Pyridazine Pyrimidines Pyazines

3. Pyridazine
(1,2 Diazine)
Preparation
1) From Maleic Acid
2) From 1,4 diketones
3) From Tetrazines
N
N
Pyridazine
O
O
O
NH2
NH2
Cl
H O
H2
N
NH
OH
O N
N
Cl
Cl
N
N
H2, Pd/C
POCl3
+
NH2
NH2
N
N
O
O
N
N
+ Air
-2H2O
N
N
N
N
+
N
N
-N2

4. Reactions
 Electrophilic substitution reactions:- Pyridazine undergoes
electrophilic substitution with great difficulty, its different type of
product synthesis via its N-oxide.
 Reduction:-
 Nucleophilic substitution reactions:-
 Photochemical reactions:-
N
N
N
N
N
N
N
N
N
N
OH
Cl
Cl
Cl
Py CCl3CHO
N
N
NH
NH
Na/CH3OH
N
N
C6H5CO3H
N
N
O -
HNO3
H2SO4 N
N
O
-
NO2
hv

5. Pyrimidines
 Preparations
 From Malonic acid:-
 From Malic Acid:-
O
O
H
O
OH
O
NH2
N
H2
+
NH
NH
O
O O
N
N
OH
OH
O
H
N
N
Cl
Cl
Cl
N
N
POCl3
Zn dust
H2
O
O
OH
O
O
H
OH
H
O
NH2
N
H2
NH
NH
O
O
N
N
OH
OH
N
N
Cl
N
N
POCl3
Pd/C
H2
O
O
O
H +
-2H2
O
conc.H2
SO4
-CO2
-H2
O
N
N
Pyrimedine
(1,3 diazine)

6. Resonating Structure
 At 2, 4, and 6 positions due to electron deficient the attack of
electrophile is retarded.
 Attack at 5-position is also difficult due to inductive effect of two
‘N’atoms.
 If one or more electron withdrawing group are present on ring, the
electrophilic substitution at5-position is easy.
N
N
N
N
N
CH
+
N
–
N
CH
+
N
–
N
N
–
C
H
+
1 2 3 4 5
1

7. Reactions
 Electrophilic substitution reactions:- If two electron releasing groups
are present on the ring ,electrophilic substitution become
enhanced.
* Nitration:
 Reactions with oxidizing agents:-
N
N
OH
OH
N
N
OH
OH
fuming HNO3
N
N
N
N
H2
O2
, CH3
COOH
POCl3

8.  Nucleophilic substitution reaction:-
* Reaction with Grignard reagent:-
* Reaction with boiling hydrazine:-
N
N
N
N
Mg
Br
NH
N
H
N
N
H+
/H2
O Acetone
KMnO4
C6
H5
MgBr
NH2
NH2
N
N
+
N
NH
+ N
H2
NH
1300
C

9. Pyrazine
 Preparations
 From 1,2 diketones :-
 From Ethylene Oxide:-
N
N
O
O
+
NH2
N
H2
N
N
CuCrO3
3000
C
Reflux
N
N
NH
NH
O
+
N
H2
NH2 Air
-H2
O
N
N
Pyrazine
(1,4 diazine)

10. Reactions
 Reduction:-
 Oxidation:-
 Nucleophilic substitution:-
NH
NH
Na/CH3
OH
N
N
N
N
N
N
H2
O2
, CH3
COOH
N
N
N
N
CF3COOH
O
O-
-
+
+
+
O
-
N
N
Cl
Cl
N
N
O
Cl
O N
N
NH
+
LiHMDS, ToIH NH3
MeOH
1700
C

11. Thank
You