Diazines

Synthesis and reactions

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

2. Introduction
Diazinesare 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 isolobalNitrogen.
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 TetrazinesN
N
PyridazineO
O
O NH
2
NH
2 ClH OH
2 N
NH
OH
O N
N
Cl
Cl N
N H2, Pd/C POCl3 + NH
2
NH
2
N
N
O
O
N
N
+ Air -2H2O N
N
N
N
+
N
N -N2

4. Reactions
Electrophilic substitution reactions:-Pyridazineundergoes
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/CH
3
OH N
N
C6H5CO3H
N
N
O
-
HNO3
H2SO4
N
N O - NO2 hv

5. Pyrimidines
Preparations
From Malonicacid:-
From Malic Acid:-O
OH
O
OH
O
NH
2
NH
2+
NH
NH
O
O O
N
N
OH
OHOH
N
N
Cl
ClCl
N
N
POCl
3
Zn dust
H
2
O O
OH
O
OH
OH
H
O
NH
2
NH
2
NH
NH
O
O
N
N
OH
OH
N
N
Cl
N
N
POCl
3
Pd/C
H
2
O
O
OH +
-2H
2
O
conc.H
2
SO
4
-CO
2
-H
2
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
–CH
+
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 HNO
3 N
N
N
N
H
2
O
2
, CH
3
COOH
POCl
3

8. Nucleophilic substitution reaction:-
* Reaction with Grignard reagent:-
* Reaction with boiling hydrazine:-N
N
N
N
Mg
Br
NH
N
H
N
N
H
+
/H
2
O
Acetone
KMnO
4
C
6
H
5
MgBr NH
2
NH
2
N
N
+
N
NH
+
NH
2
NH 130
0
C

9. Pyrazine
Preparations
From 1,2 diketones :-
From Ethylene Oxide:-N
N
O
O
+
NH
2
NH
2
N
N
CuCrO
3
300
0
C
Reflux N
N
NH
NHO
+
NH
2
NH
2 Air
-H
2
O N
N Pyrazine
(1,4 diazine)

10. Reactions
Reduction:-
Oxidation:-
Nucleophilic substitution:-NH
NH
Na/CH
3
OH
N
N N
N
N
N
H
2
O
2
, CH
3
COOH
N
N
N
N CF
3
COOH
O O - - + + + O - N
N
Cl
Cl
N
N
O
ClO N
N
NH
+
LiHMDS, ToIH NH
3
MeOH
170
0
C

11. Thank
You