Environmental Engineering Reference
In-Depth Information
C
6
H
5
CH
2
ONO
2
+2H
2
O
C
6
H
5
CH
2
OH+H
3
O
+NO
3
H
2
O
C
6
H
5
CH
2
ONO
2
C
6
H
5
CHO+HNO
2
Based on the hydrolysis of those nitrate esters, it can be obtained that there are
three paths for nitrate ester hydrolysis [
36
].
Y
!
NO
3
RCH
2
CH
2
ONO
2
þ
RCH
2
CH
2
Y
þ
RCH
2
CH
2
ONO
2
Y
!
NO
3
þ
RCH
¼
CH
2
þ
HY
Y
!
NO
2
þ
RCH
2
CH
2
ONO
2
þ
RCH
2
CHO
þ
HY
where Y is hydrolytic reagent.
The
first path of hydrolysis is the nucleophilic substitution reaction. In the second
path, a hydrogen atom at
ʲ
position is eliminated. In the third path,
ʱ
-H atom is
supposed to be removed.
Those reactions only happen in the alcohol aqueous solution of monohydric
alcohol nitrates. It should be noted that methyl nitrate cannot be reacted in the
rst
path, while tert-butyl nitrate cannot be hydrolyzed in the third path. The product
amount of methyl nitrate hydrolysis through the third path is very small. Only 4 %
ethyl nitrate is hydrolyzed in the
first and second paths. The other nitrate esters
would be completely hydrolyzed in the
first path. The ratio of the reaction velocity
for three reaction paths is 70:7:1.
If sodium sulfhydrate, equal to basicity of pH 10
-
11, is used in hydrolysis, 93 %
N-ester group of nitrate esters is hydrolyzed to nitrous acid ions and 7 % is
hydrolyzed to ammonium. If ammonium sulfhydrate is used, the concentration of
nitrous acid ions will be increased to a maximum
rst and then decreased to zero
because of the reduction of ammonium sulfhydrate. The reduction effect would be
increased with increasing pH value, especially at pH over 10. The reaction can be
expressed as following chemical equations.
C
4
H
9
ONO
2
þ
!
þ
NaNO
2
þ
2NaHS
C
4
H
9
OH
NaHS
2
C
4
H
9
ONO
2
þ
þ
!
þ
þ
4NH
4
HS
3H
2
O
C
4
H
9
OH
4S
4NH
4
OH
In the hydrolysis process of cellulose nitrate by sodium sulfhydrate [
37
], the
products are formed in regenerated cellulose.
C
6
H
8
O
3
ONO
2
ð
Þ
3
þ
2NaHS
!
C
8
H
10
O
5
þ
2NaNO
2
þ
2S
2NaHS
þ
2S
!
Na
2
S
3
þ
H
2
S
The reduction mechanism of cellulose nitrate hydrolysis in sodium sulfhydrate
can be expressed as:
