Photochemical degradation of brominated dibenzo-p-dioxins and -furans in organic solvents

Chemosphere, Voi.22, Nos.9-10, Printed in Great Britain

pp 821-834,

1991

PHOTOCHEMICAL

BROMINATED

DIBENZO-P-DIOXINS

DEGRADATION

OF

0045-6535/91 $3.00 t 0.00 Pergamon Press plc

AND

-FURANS

IN

SOLVENTS

ORGANIC

D. L E N O I R

, K.-W.

SCHRAMM,

CHAIR OF E C O L O G I C A L UNIVERSITY *Present

OF BAYREUTH,

address:

RESEARCH

O. H U T Z I N G E R A N D G. S C H E D E L

CHEMISTRY

8580 BAYREUTH,

INSTITUTE

CENTER,

AND GEOCHEMISTRY FRG

OF E C O L O G I C A L

INGOLST~%DTER LANDSTR.

CHEMISTRY,

GSF

I, 8042 N E U H E R B E R G ,

FRG

ABSTRACT

The

photolytic

behavior

of

halogenated

dibenzo-p-dioxins

and

-furans

in

the

organic s o l v e n t s m e t h a n o l and n - h e x a n e was i n v e s t i g a t e d and the c o r r e s p o n d i n g quantum-yields

and

first

order

decay

rates

are

reported.

The

photolysis

constants in n - h e x a n e i n c r e a s e w i t h i n c r e a s i n g n u m b e r of b r o m i n e atoms in the dibenzo-p-dioxin monobrominated 4.0x10 -3 furan. The

s -I

or

for

analogues.

7.7xi0 -3 the

Photolysis

bromine

dibenzofuran

to

for

dibrominated

in m e t h a n o l

compounds The

skeleton,

s -I

react

results

is

an

were

to

used

of

to

from

4.5x10 -4

octabrominated

8.3x10 -2

nearly

order

e.g.

the

six

s -I

for

s -I

the

from

heptabrominated

slower

than

in

magnitude

faster

than

the

the

the

and

times

extrapolate

for

dioxin,

n-hexane. chlorine

photochemical

fate

to

via

the

et

al.

lipohilic e n v i r o n m e n t a l surfaces.

INTRODUCTION

Brominated

dibenzodioxins

combustion

of

1988).

E.g.

et al.

1988)

considerable

various

and

-furans

technically

polybrominated

amounts

during

enter

produced

diphenyl

in p l a s t i c m a t e r i a l s

can

ethers

bromine used

have been

incinerations

The

toxicity

HARDY

1990,

compounds

of

(NEUPERT, NAGA0

PBDD/F WEISS 1990).

is t h e r e f o r e

has et The

been

al.

knowledge

important.

flame

(PRICE

to y i e l d

PBDD

and

(CULLIS PBDF

(DUMLER et al.,

to

be

the

similar IVENS

to

1989,

environmental

their

chlorine

DILIBERTO fate

of

In a d d i t i o n to i m p o r t a n t e n v i r o n m e n t a l

82l

in

1990).

LOSER, of

as

retardants

of these m a t e r i a l s

found

1989,

environment compounds

as

shown

DUMLER et al., H U T Z I N G E R et al., D U M L E R et al.

analogues

the

1990, those fate

822

parameters

such

as

vapour

estimated

octanol-water

pressure

measurements

partition

(FIEDLER,

(RORDORF SCHRAMM

et

al.

1990)

p h o t o c h e m i c a l aspects of these compounds w e r e studied some time ago Since p h o t o c h e m i c a l pathway

for

these

photochemistry

in

1989)

and

some

of

(BUSER).

d e g r a d a t i o n of PBCD/F m i g h t be an i m p o r t a n t d e s t r u c t i v e compounds

more

detail

in

the

using

environment

two

we

different

have

solvents

studied

its

(n-hexane

and

methanol). One

aspect

of

the

investigations

was

to q u a n t i f y

the d i f f e r e n t

photolytic

d e c o m p o s i t i o n of PBrDDs d e p e n d i n g on their degree of bromination.

EXPERIMENTAL CHEMICALS

Table 1 lists all i r r a d i a t e d compounds and their sources. In

addition

dioxins, i). All

in

our

chlorinated

laboratory

were

toluene.

directly

Each

here

in n - h e x a n e

irradiated

i0

ml

of

I:

Compounds

Geochemistry

as

brominated/chlorinated internal

(Promochem). or methanol.

vessel

contained

stock

solution

the

d i b e n z o f u r a n s were also irradiated,

Table

and

used

solvents used w e r e n a n o g r a d e

and d i s s o l v e d

BrDD;

several

investigated.

standards

(see

also

Table

The c o m p o u n d s were w e i g h t e d Standards

2 ml w i t h was

dibenzo-p-

the

were

dissolved

exception

irradiated.

Three

of

in

octa-

brominated

see Table II.

(i)

Chair

of

Ecological

(2) W e l l i n g t o n C h e m s y n Science L a b o r a t o r i e s

Chemistry

and

(3) P r o m o c h e m

* C o n t a m i n a t e d w i t h 5% h e p t a - B r D D Compounds

irradiated

Standards nm

1 / 2-mono-BrDD

(i)

2,7 / 2 , 8 - d i - B r D D 1,3,7-tri-BrDD

2 - mono - CDD

(2)

(i)

octa-CDD

1,2,3,7,8-penta-BrDD

(3)

1,2,4,7,8-penta-BrDD

(2)

1,2,3,4,7,8-hexa-BrDD (i)

(i)

1,2,3,4 - tetra - CDD

(i)

(2)

1,2,3,4-tetra-BrDD

octa - BrDD

(i)

(i)

(i)

1,2,4,7,8-penta Br-3,6,9-tri-CDD octa - BrDD

(i)

(i)*

1,3,4,6,7,8,9-heptabromo-2-mono-CDD

(1)

823

EQUIPMENT A Rayonet external fixed.

Photochemical

wall

Reactor

maximally

Eight

vessels

(RPR-100)

low-pressure

rotate

axially

vessels

absorb

The

purification

they were heated to 280 °C.

lamps were times

experiments

sufficient

remained

very

short.

it varied

The

sample

experimental For

compounds

ranged from 15 minutes added to each sample.

analysis

experiment.

For n-hexane

protected

by

spectrum

for b r o m i n a t e d

the period

can

(modell

below

280

nm.

be

MGR) For

compounds

two m e r c u r y

Nevertheless

irradiation

was

0.5

to

Each sample was

aluminium

At the

(RPR-3000A)

merry-go-round

lamp

from 1 to 22 minutes.

was

for irradiation.

lamps

and

14.5

minutes,

irradiated

exposed

at

the

once.

maximum

time.

chlorinated

the solution

that

used

a

the

for the photolysis

for methanol control

showed

was

mercury in

apparatus.

Some p r e l i m i n a r y

pyrex

16

was

lamps

could

be used,

to 12 hours.

After

irradiation

whereby

(N2-stream).

Fig.

to dryness

and r e - d i s s o l v e d

1 shows the spectral

~rel

I

l

f

300

i

I

I

I

3~

I

I

I

I

I

I

i

400

Flg. I Relatlve Spectral Olstrlbutlon of the UV-Lamp

I

f

I

450 nnl

standards

to microvials. in toluene

distribution

experiments.

I 250

irradiation

internal

The sample volume was transfered

evaporated

for the i r r a d i a t i o n

14

times were

Finally

for GC/MS

of the lamp used

824

RESULTS

AND

PHOTOLYSIS

DISCUSSION

IN n-HEXANE

Photolysis

of

fast

n-hexane.

in

dibenzofurans follow

all

are

a good

AS

nine

brominated

The

also

first

SOLVENT

corresponding

included.

order

dibenzodioxins

The

kinetic

investigated

results

rate

of

scheme.

for

three

degradation

In Table

II

occurs

of

the

very

brominated

all

compounds

calculated

first

order rate constants k are s u m m a r i s e d along w i t h the q u a n t u m - y i e l d s

Table

II:

Photolysis

constants

(k)

and

Quantum

Yields

(~)

of

Brominated

D i b e n z o d i o x i n s and -furans in n - h e x a n e as solvent.

Co~pound

k (s -1)

• (mol einst -I)

MonoBrDD

4 . 4 6 x 1 0 - 3 ± 6 . 7 2 x 1 0 -4

0 14±0.02

2,7/2,8-DiBrDD

5 . 6 5 x 1 0 - 3 ± l . 0 1 x 1 0 -3

0 14±0.002

2,3,7-TriBrDD

7 . 2 6 x 1 0 - 3 ± l . 3 3 x 1 0 -3

0 45±0.08

1,2,3,4-TetraBrDD A

5 . 0 4 x 1 0 - 3 ± 3 . 3 8 x 1 0 -4

0 21±0.01

1,2,3,4-TetraBrDD B

5 . 9 4 x 1 0 - 3 ± l . 2 4 x 1 0 -3

0 18±0.04

1,2,3,7,8-PentaBrDD

1 . 2 2 x 1 0 - 2 ± 3 . 7 0 x 1 0 -4

0 45±0.01

1,2,4,7,8-PentaBrDD

1 . 1 5 x 1 0 - 2 ± l . 0 5 x 1 0 -3

0 42±0.04

1,2,3,4,7,8-HexaBrDD

1 . 5 5 x 1 0 - 2 ± l . 3 7 x 1 0 -3

0 53±0.05

OctaBrDD

7 . 7 3 x 1 0 - 3 ± l . 5 1 x 1 0 -3

0 17±0.03

2,8-DiBrDF

0.037

2,3,7,8-TetraBrDF

8.98x10 -2

1,2,3,4,6,7,8HeptaBrDF

These

8.28x10 -2

experiments

show

that

0.712

the

rate

constants

increase

moderately

with

increasing numbers of bromine atoms. The same trend is o b s e r v e d in the series of b r o m i n a t e d d i b e n z o f u r a n s . rate

for

OBrDD

does

not

follow

this

general

pattern

since

it

is

But the

decreased

compared to h e x a b r o m i n a t e d compound.

The

reaction

dibenzodioxins

products have

been

formed

in

determined

the in

photolysis dependence

of of

c o n s e c u t i v e s u b s t i t u t i o n of bromine by h y d r o g e n does occur;

all

time.

brominated In

see Fig.

general, 2-5

825

PRODUCTS OF P H O ~ L Y S I S The

reactions

for all This

behavior

brominated

products

The

mass

is

were

balance

reactions

followed

No

must

degraded

sho~

PELLETIER,

GC/MS.

is

photolysis

photolytic

photolytic in

in

that

bilance.

with

were

to

the

Br/H

for

m a y also

higher

Fig.

as

exchange

dibenzodioxins

DiBrDD show a ring fission of one ether bridge;

the

see

2-5.

solvent.

some

other

dibenzodioxin

o-hydroxybenzoic

pathways

dete~ined

debromination.

n-hexane

unsubstituted

to

brominated

due

dibenzodioxins,

to the

n-hexane

Lower

factors

degradation

studies

addition

likely

But other d e g r a d a t i v e

mass

response

accumulates

octabrominated

in

that

It

The

product

the

to

observed shows

1987).

the n e g a t i v e

for

tetra-

occur.

by

by

debromination

products;

All

be

were

isomers.

acid

can

(MASSE,

be r e s p o n s i b l e

for

like m o n o B r D D

and

e. g.

Br

0 ~

~

+

h~

0

This

Br

reaction

(CHOUDHRY, monoBrDD shows

has

HUTZINGER, and

that

monoBrDD,

type

been

described

1982).Ass~ing

monoBrPE

is

much

more

it a c c u m u l a t e s

the d i b r o m i n a t e d d i b e n z o d i o x i n s but

to

an

monobromoh~roxybiphenyl

because

a minor

extent.

With

for

low

chlorinated

identical

ether

stable

response

(monoBrDPE)

towards

dibenzodioxins

a

factor

quantification

photolysis

compared

in the m i x t u r e of the r e a c t i o n products. the same r e a c t i o n

TriBrDD

ether products are o b s e r v e d at all.

and

higher

(ether fission) brominated

for

BrDD

to For

is o b s e r v e d no

diaryl-

it ......

iL

'

• " 'iJ,

iiL' 3

i 'i

(3O

827

Concentration in ppm 160 - 8W

- 1,25 mifl

- 2,5 rain

4 r?lm

6 rain

- 9 rnin

13 rnin

140 120 100

jj

60 4O

12345678

h

01234567

0~2345678

0123458?0

012340670

12345078

012345670

Number of Bromine Atoms

Fig. 5 Productsformedfrom Photol~is of Octl BrDD

S T E R I C R E L A T I O N OF T H E B R O M I N E S U B S T I T U T I O N P A T T E R N T O R A T E C O N S T A N T S

Bromine

in lateral

positions found

this

irradiated halogens

positions

(1,4,6,9); relation the

total

destabilize

of

2,3,7,8-CI(4)XDD

stereospecifity for

OCDD

set

of

and 22

C-X bonds

isomers

in the radiation

case of

1,2,3,4,7,8-Br(6)XDD

is two

reacts

observed. CI(6)XDDs.

isomers

of

1983),

of 1 , 2 , 3 , 4 , 7 , 8 - B r ( 6 ) X D D products

were

than the peri

(1976,

NESTRICK

CI(4)XDD.

(NAKADA et al.

two

faster

BUSER

1979)

et

al

Additionally

which was

shown

and 1,2,3,4-Br(4)XDD. formed

the

has

(1980) vicinal for both In the

1,2,3,7,8-Br(5)XDD

and 1,2,4,7,8-Br(5)XDD. Fig.

4 confirms

1,2,4,7,8-Br(5)XDD

than

1,2,3,7,8-Br(5)XDD.

1,2,7,8-Br(4)XDD Br(4)XDD formation Br(6)XDD

could and

are not

For Br(4)XDDs

assumed appear

accumulation

from relative

as main

to

be

during has

values

the

which

1,3,7,8-Br(4)XDD,

formed

been

product

as

main

photolysis found

in

the

is more

1,4,7,8-Br(4)XDD

products. of

Since

of

and

1,4,7,8-

1,2,3,7,8-Br(5)XDD

reaction

of 0.24 to 1 as the dominant

of the isomers after 0.5 min and 14 min reaction

photostable

its

1,2,3,4,7,8-

isomer.

The ratios

time are shown below:

828

ar

Br

Br Br

J

"a

Br B r ~ i ~ B r

Br ,

~

Br

Br Br

0

"

--

~

Br

0~ ~

Br Br

Br

Br~O~]~ Br Br

0

Br

t :

0.5 min

1

0.48

0.01

teL. ratio

+~ =

14

]

0.24

_

teL. rotio

Similar

min

conclusions

1,2,4-Br(3)XDD

can

be

drawn

has lower photolytic

for

1,2,3,4-Br(4)XDD

rate constants

(Fig.

3)

(BUSER :

1988).Here

829

ar

0

Br

/ Br ~

i

Br

~

Br

~

i

~

Br

Br

Br

t = I min

1

:

0.29

teL. folio

t = 14 rain

1

:

0.16

teL. folio

Again the stability of 1,2,4-Br(3)XDD can be explained by the two halogens peri-position and the ortho substituted halogen at position

in

i.

PHOTOLYSIS OF 1 , 2 , 3 , 4 - C I ( 4 } X D D IN n - H E X A N E

For comparative CI(4)XDD

reasons

irradiated

orders of magnitude

in

chlorinated n-hexane

dibenzo-p-dioxins

shows

a

rate

were

constant

lower (Fig. 6).

Conoentratlon in ppm BW

15 m,

60 min

180 rnin

BOO 700600 500 400 300 200 100

~234

1234

0?23

0T234

Number of Chlorine Atoms

Fig. 6 Products formed from Pholo~sis of 1, 2, 3, 4-Tetra-CIOO

Figure 6"

Photolysis of 1,2,3,4-CI(4)XDD in n-Hexane.

studied.

which

is

1,2,3,4over

two

830

The quantum yields are determined as:

• I,2,3,4-CI(4)XDD:

0.0064 ± 0.004

(mol einst. -I)

~I,2,3,4-Br(4)XDD:

0.18

(mol einst. -I)

± 0.04

The quantum yield of the bromine compound

is 28 times

chlorine

photolytic

analogues

resulting

in a

faster

larger compared reaction

of

to the

the

former

micropollutants. In

general

halogens

the

(BUNCE

determines

triplet-energies et

the

al

1975).

rate

are

Thus

independent

of

the bond-energy

constants.

BUSER

(1988)

the

identity

is the main found

a

of

the

factor which stereospecific

photoreaction of the bromoatoms when mixed halogenated PXDDs were radiated. NAKADA

(1983)

has

tetrahalogenated strong

influence

constants.

Fig.

measured

benzenes. of

the

6 shows

similar

However, position

that

no

differences

for

the

rate

tri- and dihalogenated which

product

could

appears

lead which

constants

of

benzenes exhibit a

to

equivalent

could

rate

compensate

losses of 1,2,3,4-CI(4)XDD.

PHOTOLYSIS

IN M E T H A N O L

The photolysis of 1,2,3,4-Br(4)XDD was faster in n-hexane than in methanol.

Concentration in ppm

800

BW

1rain

2,5n

4,5rnin

7,5m

11,5n

l 8 rain

22 rain

- -

700-600 --

400 -500--

1

~-

300--

m

100 -o-0t234

~ 11234

e 1234

1234

0123

Number of Bromine

01234

1234

0T234

Atom

Fig. 7 Products formed from ~otolysis of 1, 2, 3, 4-Tetra-BrDD in Methanol

Figure 7:

Photolysis of 1,2,3,4-Br(4)XDD

(0.54mg/50ml)

in methanol.

the

831]

The

first

order

subscripts

rate

constants

for

two

experiments

denoted

with

the

(1982)

for

1 and 2 are given as:

kMe0H 1

1.119

10 -3 ± 1.57 10 -4

(s -1)

kMeOH 2

8.465 10 -4 ± 3.20 10 -4 (s -1)

kHex I

5.041

10 -3 ± 3.38 10 -3

kHex 2

5.947

10 -3 ± 1.24 10 -3 (s -1)

(s -1)

Thus the q u a n t u m - y i e l d s

are:

• MeOH 1

0.025 ± 0.009

(mol einst. -I)

#MeOH 2

0.037

(mol einst. -I)

• Hex I

0.18

± 0.04

(mol einst. -I)

~Hex 2

0.21

± 0.01

(mol einst. -I)

± 0.007

This result is in c o n t r a s t to the report by C H O U D H R Y and H U T Z I N G E R chlorinated dioxins who found faster p h o t o l y t i c r e a c t i o n s

MECHANISM

in methanol.

OF THE REACTION

The p r i m a r y

step of

the p h o t o r e a c t i o n

is the

absorption

of

a quantum,

which

results in an e x c i t a t i o n of the a r o m a t i c ~-orbital;

i(~,~) This

h~

singlet

triplet

I(~,~*)

orbital

stage.

favorable,

e

In

since

l(~,~*)-orbital

can

undergo

brominated

the

intersystem arenes

3(o,o*)-orbital

(NAKADA et al,

this has

crossing

with

spin

process

can

be

a

lower

1983). A c c o r d i n g

energy

change

to a

energetically

compared

to I C H I M U R A a. MORI,

to

the

1973 the

process occurs in two steps:

3

3

3

1 The

results

with

1

chloroanisols

proposal that a d i r e c t e x c i t a t i o n can occur.

led

SOUMILLON

to the triplet

and

VERMEULEN,

1982

to

the

state -a f o r b i d d e n r e a c t i o n -

The h o m o l y t i c clevage of the C-Br bond does o c c u r from the triplet

stage by the f o l l o w i n g scheme DDBr n (DD-Brn)* DD-Brn_ 1 + RH

.....

:

~

(DD-Brn)*

~

DD-Brn_ 1 + Br"

~

DD-Brn_ 1 + R"

832

EXTRAPOLATION

The

OF

THE

determined

coefficients hourly

8

of

irradiation

character

1989).

the

order

furan.

and

2,8-Br(2)XDF densities

first

and

BEHAVIOR

n-hexane

and

flux

The

dioxin

PHOTOCHEMICAL

in

2,8-Br(2)XDD

GOSS

for

TO THE

quantum-yield

solar

(SCHRAMM, Fig.

RESULTS

As

decay

the

were

of

IN THE

ENVIRONMENT

molar

extinction

combined

environmental

rate

of

environment

a

with

common

fate

models

photolysis

0.1mm

film

is of

shown

in

lipophilic

has been t a k e n as a model.

k max (l/h) 0,25;

! ~

2,8-grgD

~

2,8-grDF

o,2 O, 1 5 -

'::::: ,\, ,,,~

i

[

O, 1 "-

0,05

--

~':

M}

:

~

1

2

....~

,,,4

3

k

~.~

4

5

6

7

8

9

10

11

12

month

Figure

8:

First

order

highest

The

decay

solar r a d i a t i o n

differences

differences as m a i n

of

of m o l a r

pathway

Solutions

result W hile

waxes

the

and

these would

n-hexane

low

not be studied,

stabilities extinction

and

can

be

mainly

coefficients. decay

2,8-Br(2)XDF

at the b e g i n n i n g

in

assigned

Since

the

hour

of

of each month.

to

debromination

can be an i m p o r t a n t

sink

the

large

is r e p o r t e d

for h a l o g e n a t e d

furans. compounds to

in l i p o p h i l i c extrapolate

an o r d e r of m a g n i t u d e

can

methanol very

2,8-Br(2)XDD

flux d e n s i t i e s

allow

in a a b o u t

surfaces to

of

of

the p h o t o l y t i c

dibenzo-dioxins

plant

rates

be

regarded

as model

can be c o n s i d e r e d solubility

and t h e r e f o r e

of

the

quantum

increased solvent

as mo d e l

those

this

environmental

yields

decay for

solvent

compounds

p o l a r protic

in

compartments in

n-hexane

compared

lipophilic

solvent

the

which

to methanol. environmental

for a q u e o u s

water,

such as

systems.

reaction

was used.

Due

could

833

REFERENCES N.

J.

Bunce,

Effects

and

S.

Safe,

L.

Electron

O.

Ruzo:

Transfer,

Photochemistry

J.

Chem.

Soc.

of

Bromobiphenyls:

Perkin

Trans.

I,

Steric

1607-1610,

1975. H.-R.

Buser:

Rapid

Photolytic

Brominated/Chlorinated

Decomposition

Dibenzodioxins

of

and Dibenzofurans,

Brominated

Chemosphere

and

17,

889-

903, 1988. H.-R.

Buser:

dioxins

Formation and Identification of Tetra- and Pentachlorodibenzo-p-

from

Photolysis

Chemosphere 8, 251-257, H.-R.

Buser:

Preparation

Dibenzo-p-dioxins

G.G.

Choudhry,

O.

Polychlorinated

Two

Isomeric

of Qualitative

and

Octachloro Compounds,

of

Hexachlorodibenzo-p-dioxins,

1979.

Dibenzofurans J. Chromatogr.

Hutzinger:

Standard Mixtures by

Ultraviolet

129, 303-307,

Photochemical

Dibenzofurans

and

of Polychlorinated

irradiation

of

the

1976.

Formation

Dibenzo-p-dioxins,

and

Degradation

Residue

Rev.

of

84,

113-

Photochemistry

of

161, 1982. G.G.

Choudhry,

Polychlorinated Review. G.G.

Halogenated

Webster:

Dibenzofurans

Toxicol.

Choudhry,

R.G.B.

Organic

Part I. Theoretical

Choudhry,

Halogenated Part

II.

Thermochemical

C.F.

Cullis,

Editors),

in

Bromine

Compounds

by

O.

Hutzinger

(D.

L.S.

(TBDD),

and

H.

Formation

of

Chem.

of Monomeric

5,, 1 ff, 1982.

of the Thermal

Formation

of

Polychlorinated

Dibenzo-p-dioxins,

Destruction

Dibenzofurans

Chem. Price,

301-331,

L.B. Kedderis,

Tetrabromodibenzo-p-dioxin ed.

and Environ.

Elsevier, Amsterdam,

J.J. Diliberto,

and

A

Dibenzo-pdioxins,

jDecomposition

Aspects

Including

Generation

Toxicol.

of the Thermal

Polychlorinated

and Environ.

Mechanistic

Compounds

(PCDDs),

1986.

Aspects

and Thermochemical

Toxicol.

O. Hutzinger:

Dibenzo-p-dioxins

14, 43-59,

Including

background

Organic

Dibenzo-p-dioxins,

Chem.

and

Mechanistic

Compounds

Diphenyls and Aromatics., G.G.

(PCDFs)

and Environ..

O. Hutzinger:

Environmental

of

and

5, 67, 1982. B.

Idden

a.

B.

J.

Wakefield,

1988.

Birnbaum:

Acute Oral Exposure to 2,3,7,8-

Organohalogen

Fiedler,

Compounds Vol.

Bayreuth,

Ecoinforma

i, Dioxin 90,

Press,

309-311,

1990. R.

H.

Thoma,

Combustion

of

Bromine

Chemosphere

19, 2023,

R.

Dumler,

Dumler,

D.

Polybrominated

Lenoir,

Containing

O.

Hutzinger:

Flame

PCDF

Retardent

and

PCDD

Polymers,

from a

the

Survey,

1989.

Lenoir,

H.

Dibenzodioxins

Decabrombiphenyl-Ether Anal. and Appl.

D.

in

Pyrolysis,

a

Thoma,

O.

(PBDD)

Hutzinger: and

Dibenzofurans

Polybutylen-Terephthalate

16, 153, 1989.

Thermal

Polymer

Formation

(PBDF) Matrix,

of from J.

834

M.L.

Hardy,

P.H.

Sistrunk,

Tetrabromodibenzofuran Organohalogen

(TBDF):

Compounds

Fiedler, Bayreuth, O. Hutzinger,

R.

Synthesis of Standards,

Phys.

with

Y, Mori:

58, 288-292,

E. L6ser,

I.

i,

D.

C.

Chemosphere,

McFadden:

Toxicity

ed.

by

Study

O.

2,3,7,8in the Rat,

Hutzinger

and

H.

1990.

Teufl,

Combustion

Photolysis

90,

313-316,

Lenoir,

D.J.

Subchronic

Dioxin

Ecoinforma Press, Dumler,

Eldan,

4 Week

Vol.

Brominated Flame Retardents;

T. Ichimura,

M.

H.

Thoma:

Equipment,

18,1235,

PBDD

and

PCDF

from

Analytical Methodology and

1989.

of Monochlorobenzenes

in Gas Phase,

J. Chem.

1973.

Ives:

Preliminary

Results

of a

2,3,7,8-Tetrabromodibenzo-p-dioxin

3 Month

Toxicity

(2,3,7,8-TBDD),

Study

Chemosphere

on Rats 19,

759,

1989. R.

Masse,

B.

Pelletier:

Solvents

at

Products,

Chemosphere

T.

Nagao,

Frequency

253.7

nm:

Photochemistry

GC/MS

16, 7-17,

J.Golor,

R.

Induced

by

of

Dibenzo-p-dioxin

Characterization

of

the

D.

Neubert:

Comparison

of

Cleft

2,3,7,8-Tetrabromodibenzo-p-dioxin

90, ed. by O. Hutzinger

Organic

1987.

Krowke,

Tetrachlorodibenzo-p-dioxin

in

Phototransformation

in Mice,

Organohalogen

and H. Fiedler,

Bayreuth,

and

Compounds

2,3,7,8-

Vol.

Ecoinforma

Palate

i,

Press,

Dioxin

317-319,

1990. RM. Nakada,

S. Fukushi,

Photochemical

Dehalogenation

in Hexane Solution, M.

Neupert,

H.

Connection

with

B.

Stock,

J.

Toxicity

Ishii:

I. Survey of the Reactivity

56, 2447-2451, Thiess:

T.

1983.

Analytical

Studies,

Procedures

in

Tetrabromdibenzo-p-dioxin

19, 115, 1989. L.L.

Lamparski,

Tetrachlorodibenzo-p-dioxin and

D. Kume, M. Hirota,

of Polyhalobenzenes.

Accute

Nestrick,

Degradation

K. Kubo,

Bull. Chem. Soc. Japan.

Weiss,

(TBDD),Chemosphere, T.J.

H. Nishiyama,

Pattern

D.J.

Isemeres

Recognition

at

Townsend: the

Techniques,

l-ng

Identification Level

Anal.

Chem.

of

by

Photolytic

52,

1865-1874,

1980. D. Price,

B.

Applications, B.F.

Iddon,

L.P.

Schwind,

K.-W.

K.-U-

Environ.

J.M. Soumillon, (Received

G.R.B.

Hutzinger:

and

Chemosphere,

Schramm,

Toxicol.

Sarna,

O.

Dibenzo-p-dioxins Method,

Wakefield

Elsevier, Amsterdam,

Rordorf,

K.-H.

B.J.

20, 1603, Goss:

Webster,

Vapor

S~H.

Pressure An

Extended

Compounds,

Chemistry

and

Safe,

L.M.

Safe,

Measurements Data

Set

on

D.

Lenoir,

Halogenated

for a Correlation

1990.

MESIP-Modeling

26, 123-128,

J. Vermeulen:

Bromine

1988.

Dibenzofurans.

Chem.

in Germany

(Eds.):

Environmental

Scenarios

1990

Bull. Soc. Chim. Belg.

2 April 1991; accepted

91, 474, 1982.

25 April 1991)

in Ponds,