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Photochemistry of bis phenyl carbamates in aqueous solutions
Chemosphere, Vol.16, No.2/3, pp 513-517, Printed in Great Britain
1987
0045-6535/87 $3.O0 + .00 Pergamon Journals Ltd.
PHOTOCHEMISTRY OF BIS PHENYL CARBAMATESIN AQUEOUSSOLUTIONS by P. M~allier and J.P. Percherancier Laboratoires de Photochimie - Universit~ Claude Bernard LYON I 43, Boulevard du 11 novembre 1918 - 69622 Villeurbanne - France M. Mansour GeselIschaft fur Strahlen- und Umweltforschung mDH M~inchen I n s t i t u t fur ~kologische Chemie D-8050 Freising-Attaching F.R.G. We present the photodegradation of some bis phenyl carbamates which are phenmedipham's derivatives.
F X
oo.
0
Nucleus I
Nucleus I I
X is a substituant : H - Cl - F - NO2 or CH3 for phenmedipham. We have calculated the energy of the differents excited states, the quantum yields of fluorescence, phosphorescence and of photodegradation. The spectroscopic study and the knowledge of the photoproducts permit us to give a mechanism of reaction.
Spectroscopic properties The absorption of phenmedipham is contained between 200 and 450 nm. Our results are relative to the f i r s t absorption band in different solvents (table I and I I ) . When we study the results we ren~rk the high value of the molecular extinction c o e f f i cient, the low influence of solvents and substituants, i f we except the particular case of the nitroderivative. We have a band of charge transfer. The energy of : - the f i r s t singlet state is
415 Kj
- the f i r s t t r i p l e t state is
320 Kj
More important is the influence of the wavelength, when we use E.P.A. as solvent phosphorescence experiments.
513
514
®
Eau
X H
" (.
Ethanol
Hexane
x
x
~
%-
27Y
1500
279
2400
3-C113
278
1700
279
1800
277 2100 278
1500
4-C113
283
2700
278
34oo
284
34oo
3-CI
282
1400
283
2000
282 2200
4-CI
281
2600
278
2900
277 2900
3-CF3
283
2800
279
3200
283 2900
4-N02
310
11950
310 11900
309 13000
B
TABLE I : Maxima of absorption an molecular extinction coefficient
..~O/,VAA~' CONDITIONS D'F..XPERIHENTATZON SUaSI|TUA~r H 5,10 -5
U
~exC
IF max (rim)
~F
%
ES1 kJ,=ole -L
20;
300
1,5.10 -2
419
260-28~
300
3.10 -2
1,7,10-2
418
260-285
300
3,3.10 -2
420
260-285
300
2,7. I O-2
411
260-285
300
5. I 0-2
415
260-285
300
6. Io -2
410
5.10 -5
260-285
20"
4'4~ 3 3".Cl
260-285
20"
300
0,5,10 -2
5.10°5H
(,~)
260-285
5.10 -5
pherm
~exc
kJ.mote -I
kV max
t°
3 r.H3(phenm)
lk-~ 2
£S 1
(1~)
300
3"~3
HEXANE
ZTIIAHOL
(.n~)
422
5.10 -5
260-285
20°
300
1,9.10 -2
415 412
5.10 -S
260-205
20"
300
I,S,IO -2
412
5.10 -$
260-285
20"
300
6,3.10 -2
412
260-285
300
JO. 10 -2
414
5,10 -4
260-330
20"
430
< IO-3
335
260-350
420
< 5, 10-3
340
Solvant
t"
exc (nm)
£thanol
20"C
260-285
Hexmne
20"C
260-285
~exc
ES I £T! mole-I k.j ~ l e - I !
~F
~P
max
Nx
3
300
-
0.017
418
3
300
--
0.033
/415 420
(.m)
#r
@p
--
d|oxmm~ne esu
20°C
260-285
3
300
--
0.11
20"C
260-285
3
300
-
0.04
HP *
77°K
260-285
$
295
410
0.10
0.50
-
]20
LPA 00
77"K
260-275
5
300
&20
O,O&
0,10
--
325
£FA
770K
260-295
5
300
420
0,06
0,40
_
325
TABLE I I :
Emission of bis phenyl carbamates
N-B
JT 3 D Aj-pe~ell
I~ ~EA~N ApT,srell
515
The quantum y i e l d of phosphorescence is dependant of the wavelength of excitation 260 < ~ex < 275
@p = 0.10
280 <
@p = 0.40
ex < 285
We explain this result by the following mechanism 1,2,3 TI
+ T1
-~
X + SO
annihilation t r i p l e t - t r i p l e t
X
+ SO
+
S1 + SO
X : excited state
SI
For the nitroderivative the results of absorption and emission are d i f f e r e n t . We have an inversion between the transition 1A + 1La and 1A ÷ 1Lb for the cycle which has the substituant NO2. This inversion explains the high value of the molecular extinction c o e f f i cient at 310 nm and i t s low value at 230 nm. We find the same "red s h i f t " for the wavelength of fluorescence, and in these conditions fluorescence comes from the aromatic nucleus substi. tuted by NO2. We have an energy-transfer between the nucleus I I and the nucleus I. These results are obtained by calculation with a semi-empiric method 4,5,6 I
I
!
Lt uoyau II
t b aoysu II
t b novau I
cOavenion interne
ILsu~aul
/
I~aQ~e~ d'~ner~|e u~rS"rn°idcuj-z~re bV sbsmbdo ~ 270 am
hV sb~(xbh k 279 m
FIG I
I
hV dm~l k 430 um (~uorucesce)
S 0
E n e r g ytransfer for nitro-compound
.Photodegradation : Kinetic and photopr_oducts We use an annular photoreactor for our experiments, the lamp emits at 254 nm (2 x 1018 photons/sec). The values of the quantui, yield of photodegradation (Table I l l ) and the effects of diphenyl are characteristic of a t r i p l e t state reaction ( f i g I I ) .
516
pilotolyoe
I
t ,
irradLation
hexane
238 r ~
4,0.10 -2
254 am
3,5.|0 -2
262 mu
3,3.10 -2
Ill
Ethanol d~gaz6
a~r[
15,0.10 -2
0 , 9 5 . 1 0 -2
a~rl
TABLE
du phenm~diphame d~gaz~
I,O. lO- 2
eau
dioxane
a~r~
a~r6
1 , 4 . 1 0 -2
5,8.10 -2
1 , 3 . 1 0 -2
6,8.10
-2
1 , 3 . 1 0 -2
0,99.10 -2
Quantum yields of photodegradation of phenmedipham
i
o.s
FIG I I
i
I.O
l
I.s
2.o
~ [ O~,,E~:(LE] ( .lO",',t )
Desactivation of phenmedipham by diphenyl
The mechanism of photodegradation is radicalar. The product e ~'azodisobutyronitri]e (ADBN) gives radicals when i t is heated or irradied. In presence of ADBN we note an increase of the quantum yield of photodegradation (in water) = This r e s u l t
8.7 x 10-2
i s in good agrement w i t h t h e d a t a o f t h e t a b l e
III.
5I?
We propose the mechanism
XL ~ ~ "
NH- O ICl- O L ' I J '~~ [ ' N H - O IClO-CH3
x N"C
•
"O~ , N H -
7,8,9.
+ Solvent
.C,oOCH3 + Solvent
hv ,
hu,[]
3 _ _ _ ~ X ~ NH""O 'c' +XZ))j~,yN L~,~~ I'I"O ,C,O CH3
C,
~)
hv ? H ' ~ " N H ' C
I
II ,
OC H 3=
NH2
OH'•
COCH3 O
When we consider 100 excited molecules : 10 give fluorescence 50 give phosphorescence 40 give reaction or desactivation without radiation
Bibliography : 1 - C.A. Parker and C.G. Hatchart
Proc. Chem. Soc., 386, 165, 1962.
2 - B. Stevens and M.S. Walker - Chem. Comm., ~, 8, 1965. 3 - G. Porter "Reactivity of the photoexcited organic molecules". Interscience Publishers John Wiley - NY, 100, 1967. 4 - J. Petruska - J. Chem. Phys., 3_44, 1120, 1965. 5 - P.E. Stevenson - J. Mol. Spectry, 15, 220-256, 1965. 6 - C.C. Trametz and H.H. Scmidtke - Theor. Chim. Acta Allem., 4__22,13-22, 1976. 7 - W. Bussacchini, B. Pouyet and P. M~allier - Chemosphere, 1_~4, n° 1, 155-156, 1985. 8 - M. Mansour - personal communication 1985. 9 - M. Mansour - Photochemical Process Affecting the Fate of SomePesticides in the Aquatic Environ~nt. Paper presented at the 2nd International Congress for Soil Pollution and Protection from Pesticide Residues. Zagazig University, Faculty of Agriculture, Kalubia, Egypt, 7-12 Sept. 1985.
1987
0045-6535/87 $3.O0 + .00 Pergamon Journals Ltd.
PHOTOCHEMISTRY OF BIS PHENYL CARBAMATESIN AQUEOUSSOLUTIONS by P. M~allier and J.P. Percherancier Laboratoires de Photochimie - Universit~ Claude Bernard LYON I 43, Boulevard du 11 novembre 1918 - 69622 Villeurbanne - France M. Mansour GeselIschaft fur Strahlen- und Umweltforschung mDH M~inchen I n s t i t u t fur ~kologische Chemie D-8050 Freising-Attaching F.R.G. We present the photodegradation of some bis phenyl carbamates which are phenmedipham's derivatives.
F X
oo.
0
Nucleus I
Nucleus I I
X is a substituant : H - Cl - F - NO2 or CH3 for phenmedipham. We have calculated the energy of the differents excited states, the quantum yields of fluorescence, phosphorescence and of photodegradation. The spectroscopic study and the knowledge of the photoproducts permit us to give a mechanism of reaction.
Spectroscopic properties The absorption of phenmedipham is contained between 200 and 450 nm. Our results are relative to the f i r s t absorption band in different solvents (table I and I I ) . When we study the results we ren~rk the high value of the molecular extinction c o e f f i cient, the low influence of solvents and substituants, i f we except the particular case of the nitroderivative. We have a band of charge transfer. The energy of : - the f i r s t singlet state is
415 Kj
- the f i r s t t r i p l e t state is
320 Kj
More important is the influence of the wavelength, when we use E.P.A. as solvent phosphorescence experiments.
513
514
®
Eau
X H
" (.
Ethanol
Hexane
x
x
~
%-
27Y
1500
279
2400
3-C113
278
1700
279
1800
277 2100 278
1500
4-C113
283
2700
278
34oo
284
34oo
3-CI
282
1400
283
2000
282 2200
4-CI
281
2600
278
2900
277 2900
3-CF3
283
2800
279
3200
283 2900
4-N02
310
11950
310 11900
309 13000
B
TABLE I : Maxima of absorption an molecular extinction coefficient
..~O/,VAA~' CONDITIONS D'F..XPERIHENTATZON SUaSI|TUA~r H 5,10 -5
U
~exC
IF max (rim)
~F
%
ES1 kJ,=ole -L
20;
300
1,5.10 -2
419
260-28~
300
3.10 -2
1,7,10-2
418
260-285
300
3,3.10 -2
420
260-285
300
2,7. I O-2
411
260-285
300
5. I 0-2
415
260-285
300
6. Io -2
410
5.10 -5
260-285
20"
4'4~ 3 3".Cl
260-285
20"
300
0,5,10 -2
5.10°5H
(,~)
260-285
5.10 -5
pherm
~exc
kJ.mote -I
kV max
t°
3 r.H3(phenm)
lk-~ 2
£S 1
(1~)
300
3"~3
HEXANE
ZTIIAHOL
(.n~)
422
5.10 -5
260-285
20°
300
1,9.10 -2
415 412
5.10 -S
260-205
20"
300
I,S,IO -2
412
5.10 -$
260-285
20"
300
6,3.10 -2
412
260-285
300
JO. 10 -2
414
5,10 -4
260-330
20"
430
< IO-3
335
260-350
420
< 5, 10-3
340
Solvant
t"
exc (nm)
£thanol
20"C
260-285
Hexmne
20"C
260-285
~exc
ES I £T! mole-I k.j ~ l e - I !
~F
~P
max
Nx
3
300
-
0.017
418
3
300
--
0.033
/415 420
(.m)
#r
@p
--
d|oxmm~ne esu
20°C
260-285
3
300
--
0.11
20"C
260-285
3
300
-
0.04
HP *
77°K
260-285
$
295
410
0.10
0.50
-
]20
LPA 00
77"K
260-275
5
300
&20
O,O&
0,10
--
325
£FA
770K
260-295
5
300
420
0,06
0,40
_
325
TABLE I I :
Emission of bis phenyl carbamates
N-B
JT 3 D Aj-pe~ell
I~ ~EA~N ApT,srell
515
The quantum y i e l d of phosphorescence is dependant of the wavelength of excitation 260 < ~ex < 275
@p = 0.10
280 <
@p = 0.40
ex < 285
We explain this result by the following mechanism 1,2,3 TI
+ T1
-~
X + SO
annihilation t r i p l e t - t r i p l e t
X
+ SO
+
S1 + SO
X : excited state
SI
For the nitroderivative the results of absorption and emission are d i f f e r e n t . We have an inversion between the transition 1A + 1La and 1A ÷ 1Lb for the cycle which has the substituant NO2. This inversion explains the high value of the molecular extinction c o e f f i cient at 310 nm and i t s low value at 230 nm. We find the same "red s h i f t " for the wavelength of fluorescence, and in these conditions fluorescence comes from the aromatic nucleus substi. tuted by NO2. We have an energy-transfer between the nucleus I I and the nucleus I. These results are obtained by calculation with a semi-empiric method 4,5,6 I
I
!
Lt uoyau II
t b aoysu II
t b novau I
cOavenion interne
ILsu~aul
/
I~aQ~e~ d'~ner~|e u~rS"rn°idcuj-z~re bV sbsmbdo ~ 270 am
hV sb~(xbh k 279 m
FIG I
I
hV dm~l k 430 um (~uorucesce)
S 0
E n e r g ytransfer for nitro-compound
.Photodegradation : Kinetic and photopr_oducts We use an annular photoreactor for our experiments, the lamp emits at 254 nm (2 x 1018 photons/sec). The values of the quantui, yield of photodegradation (Table I l l ) and the effects of diphenyl are characteristic of a t r i p l e t state reaction ( f i g I I ) .
516
pilotolyoe
I
t ,
irradLation
hexane
238 r ~
4,0.10 -2
254 am
3,5.|0 -2
262 mu
3,3.10 -2
Ill
Ethanol d~gaz6
a~r[
15,0.10 -2
0 , 9 5 . 1 0 -2
a~rl
TABLE
du phenm~diphame d~gaz~
I,O. lO- 2
eau
dioxane
a~r~
a~r6
1 , 4 . 1 0 -2
5,8.10 -2
1 , 3 . 1 0 -2
6,8.10
-2
1 , 3 . 1 0 -2
0,99.10 -2
Quantum yields of photodegradation of phenmedipham
i
o.s
FIG I I
i
I.O
l
I.s
2.o
~ [ O~,,E~:(LE] ( .lO",',t )
Desactivation of phenmedipham by diphenyl
The mechanism of photodegradation is radicalar. The product e ~'azodisobutyronitri]e (ADBN) gives radicals when i t is heated or irradied. In presence of ADBN we note an increase of the quantum yield of photodegradation (in water) = This r e s u l t
8.7 x 10-2
i s in good agrement w i t h t h e d a t a o f t h e t a b l e
III.
5I?
We propose the mechanism
XL ~ ~ "
NH- O ICl- O L ' I J '~~ [ ' N H - O IClO-CH3
x N"C
•
"O~ , N H -
7,8,9.
+ Solvent
.C,oOCH3 + Solvent
hv ,
hu,[]
3 _ _ _ ~ X ~ NH""O 'c' +XZ))j~,yN L~,~~ I'I"O ,C,O CH3
C,
~)
hv ? H ' ~ " N H ' C
I
II ,
OC H 3=
NH2
OH'•
COCH3 O
When we consider 100 excited molecules : 10 give fluorescence 50 give phosphorescence 40 give reaction or desactivation without radiation
Bibliography : 1 - C.A. Parker and C.G. Hatchart
Proc. Chem. Soc., 386, 165, 1962.
2 - B. Stevens and M.S. Walker - Chem. Comm., ~, 8, 1965. 3 - G. Porter "Reactivity of the photoexcited organic molecules". Interscience Publishers John Wiley - NY, 100, 1967. 4 - J. Petruska - J. Chem. Phys., 3_44, 1120, 1965. 5 - P.E. Stevenson - J. Mol. Spectry, 15, 220-256, 1965. 6 - C.C. Trametz and H.H. Scmidtke - Theor. Chim. Acta Allem., 4__22,13-22, 1976. 7 - W. Bussacchini, B. Pouyet and P. M~allier - Chemosphere, 1_~4, n° 1, 155-156, 1985. 8 - M. Mansour - personal communication 1985. 9 - M. Mansour - Photochemical Process Affecting the Fate of SomePesticides in the Aquatic Environ~nt. Paper presented at the 2nd International Congress for Soil Pollution and Protection from Pesticide Residues. Zagazig University, Faculty of Agriculture, Kalubia, Egypt, 7-12 Sept. 1985.