Mixed Drug Decomposition: Comparison to Individual Drug Mineralization, Evolution of
6.1 Introduction
6.2.3 Degradation pathways and formation of inorganic ions
137
0 20 40 60 80 100
Removal, %
CCD with Cl-
ion CCD with F- ion
DIPY CIP CHPL DIPY CIP CHPL
DIPY CIP CHPL CCD without
anion
CCD with NO3- ion
DIPY CIP CHPL
Figure 6.8. Effect of Cl-, NO3-and F- ions on drug decomposition in UVP. Experimental condition: [Single drug]0 = 0.05 mM, [CCD]0 = 0.15 mM, H2O2 = 22.5 mM, pH = 3.5, reaction time = 45 min and temperature = 25°C. Photo-reaction with an UV lamp of 12 W/m2 (9 W).
138
D2 (m/z 279.01) and D3 (m/z 280.13) molecules could form on cleavage of aliphatic amide side chain (Nie et al., 2014). D3 molecule was further broken by HO. attack to its carbonyl centre with release of NO3- and Cl- ions. HO. radical attracts Cl- atom due to its electrophilic nature forming HOCl (Nie et al., 2014). D4 (m/z 281.14) was formed by hydroxylation of side amide chain of CHPL molecule and simultaneously it get reduced to sequential products (Figure 6.10) with formation of NO3- ions. D5 (m/z 298.03) molecule was originated by hemolytic cleavage of CHPL molecule forming two intermediates of molar mass of 157.11 (p- nitro benzyl alcohol) and 161.0. The later one again was oxidized to release Cl- and NH4+. NH4+ ions were converted to NO3- to attain the maximum oxidation state of N-atom. p- nitrobenzyl alcohol was reduced to p- amino benzyl alcohol on hydroxylation reaction followed by dehydration reaction. p-nitro benzyl alcohol took part in dimerization reaction (Grither et al., 2012).
On oxidation, p- nitro benzyl alcohol yielded two products i.e., p- nitro benzoic acid (MW 171.4) and p-nitrophenol. First one has greater tendency to take part in intermolecular H-bonding (Finar et al., 2001) and formed D6 molecule (m/z 361.33). Second compound was originated on oxidation followed by hydroxylation and it was converted to a dimer molecule (D7) of p-benzoquinone with m/z = 414.20. p-nitrobenzoic acid was decarboxylated forming nitrobenzene. It originated 2-amino phenol and 1, 2-dihydroxy benzyne (catechol) through reduction followed hydroxylation. D8 and D9 molecules were chelates of Fe3+ with 2-amino phenol and catechol, respectively.
D10 to D13 products appeared on degradation of CIP molecules (Figure 6.10).
Piperazine ring basically takes part in degradation reaction forming such compounds.
Piperazine ring is very reactive towards electrophilic attack due to angle strain (Section 4.4.5 of Chapter 4). D10 (m/z 303.04) was formed on acidic hydrolysis of CIP molecule followed by partial cleavage of piperazine ring. Zhou et al. (2014) reported a similar pathway of formation of D10 molecule (m/z 303.04) during CIP degradation by ferrate (VI) with loss of an ethylene group from piperazine group. Defluorination (breaking of C-F) followed by hydroxylation gave D11 (m/z 304.11) with NaF. D12 (m/z 362.71) was originated from D10
through protonation along with partial piperazine ring breaking. Haddad et al. (2014) proposed an identical formation routes for D12 compound. NO3- ions were formed on oxidation of ethyl amine with D12. NO3- could form on C-N bond breaking of an intermediate
compou compou
sulphon of pyraz an elect yielded al. (200 / NO3-
467.12) dehydra
Figure conditio pH = 3 of 12 W
und having und on dehy
4-MAA (M nate group (
zolinone str trophilic at
with an ali 08) also show
ions. NO3-
), an ether ation.
6.9. Daug on: [Single
.5, reaction W/m2 (9 W).
mass num ydradion. It MW 218.11) (-SO3H) (Er ructure of D ttack of N-h iphatic ethy wed the for
was origina r type com
ghter-ion sp drug]0 = 0.0 n time = 45
.
mber of 239 is an ether ) is a hydro rgun et al., DIPY((Figu
hydroxyl am ylamine on rmation of 4 ated on oxi mpound wa
pectra of CC 05 mM, [CC
min and te
9.0 (m/z). T type compo olysis produ 2004). NH4
ure 6.12). D mine to N-
C-N bond 4-MAA mol idation of e
as formed
CD mixture CD]0 = 0.15 emperature =
The same c ound.
uct of DIPY
4+/NO3- ions D14 (m/z 279 acyl amine
breaking of lecule from ethyl amine
by dimer
obtained at 5 mM, Fe2+
= 25°C. Ph
compound a
Y in presenc s were evol 9.8) compou
. These two f pyrazolino m DIPY with
via NH4+ o rization of
t 10 min of
= 2.25 mM oto-reaction
also origina
ce of water lved on deg und was for o compoun one ring. G h evolution oxidation. D
D14 follow
f PFP. Expe M, H2O2 = 22
n with an U
139 ated D13
r soluble gradation rmed by nds were Gomez et of NH4+
D15 (m/z wed by
rimental 2.5 mM, UV lamp
140
OH
(R)
NH2 Cl Cl
O
(R)
N+ O- O OH
C1 C2
HO.
CHPL
NH
O N+
O- O OH
= 302.16
HO. OH
N+ O- O OH
= 281.14 + eaq-1
(m/z = 122.17) OH
NH2 OH
H+ OH
NH3 OH
-NH4+ OH OH
(m/z = 104.17) [O] NO3- D1
D4 Cl Cl
OHC O NH2
N+ O- O OH
Cl Cl
Dehydration +
OH O
Cl Cl
NH2 O
H Cl HO.
HO.
+NH4+
+HOCl
Na+ Cl- = 280.13
D3
(m/z = 123.17) Homolytic Cleavage
H
N+O- O
OH OH
NH Cl Cl
O
+
(m/z = 157.11)
+H. H
NO2 OH + eaq-1
H
NH2 OH
OH.H
NH3 OH OH
H
NH3 OH OH
HO.
H OH
NH2 OH OH
OH
(m/z = 161.0) [O]
Cl-, NH4+
NH4+ [O] NO3-
Dimerisation/-H2O H
NH3 OH
D5 = 298.03 OH
NH3 OH OH
OH [O]
O HO
N+ O O- p-nitrobenzooic acid
(m/z = 171.4)
2 O
HO
N+ O O-
O HO
N+ O O- D6 = 361.33 Intermolecular
H-bonding
[O]/HO.
HO N+
O O-
[H] HO NH2 [O]
O O
O O
H 2 H
Dimer of p-benzoquinone -CO2
N+ O O-
[H]/HO.
NH2 OH
OH OH +
Fe3+ Fe3+
NH2 O- Fe3+ 3 D8 = 417.90
O- O- Fe3+ 3 D9 = 419.17
3+ 3- D7 = 414.20
= 279.01 D2
Figure 6.10. Routes of inorganic ion evolution and CHPL decomposition in PFP.
Experimental condition: [Single drug]0 = 0.05 mM, [CCD]0 = 0.15 mM, Fe2+ = 2.25 mM, H2O2 = 22.5 mM, pH = 3.5, reaction time = 45 min and temperature = 25°C. Photo-reaction with an UV lamp of 12 W/m2 (9 W).
141
O N
F :N
NH: O
O- Protonation
Pipirazine bond breaking
O N
F +NH O
O-
H+
O N
F N
NH2
O OH N+ Hydrolysis
= 303.04
O N
OH N NH2 O
OH
= 304.11 CIP
H3O+
H
H
(m/z = 239)
+ HF NaOH Na+ F- Protonation
O
N F N NH3 O
OH
-NH4+ H O
N
OH N O OH
H
4 1
C-N bond breaking
NO3- CH3CH2NH2
NH4+
HO. D10
D11 Homolytic cleavage
O
N F NH O
OH
H
H2C NH3
HO.
CH3CH2OH + NH4+ = 362.71
D12
H+
NO3- Dehydration
O N
OH N O OH
O H N HO
N
O OH H
-H2O
O
N
OH N O O O H N HO
N
O H
Ether type compound = 415.09 D13
Figure 6.11. Routes of inorganic ion evolution and CIP decomposition in PFP.
Experimental condition: [Single drug]0 = 0.05 mM, [CCD]0 = 0.15 mM, Fe2+ = 2.25 mM, H2O2 = 22.5 mM, pH = 3.5, reaction time = 45 min and temperature = 25°C.
Photo-reaction with an UV lamp of 12 W/m2 (9 W).
142
O N
O H NH3 .
OH.
O N
OH O H [O]
H N
OH O
NH
+H+ NH
H N
OH C
OH
NO3- O
NN (E) NH Hydrolysis
O NN
H 4-MAA
C-N bond breaking
CH3CH2NH2 O
NN N
(E)
S- O O O-Na+
DIPY
NH4+
2
-2H2O H HN
N HO
C O NH
H N
OH C
O
= 467.12 D15
D14 = 279.8
Figure 6.12. Routes of inorganic ion evolution and DIPY decomposition in PFP.
Experimental condition: [Single drug]0 = 0.05 mM, [CCD]0 = 0.15 mM, Fe2+ = 2.25 mM, H2O2 = 22.5 mM, pH = 3.5, reaction time = 45 min and temperature =25°C.
Photo-reaction with an UV lamp of 12 W/m2 (9 W).