PROCESS FOR POLYBROMINATING BISPHENOXY ALKANES

PROCEDE DE POLYBROMURATION DE BISPHENOXYALCANES

English Abstract

Abstract of the Disclosure
A process is disclosed for polybrominating bisphenoxyalkanes without
cleaving either phenoxy-to-alkylene linkage, characterized by reacting a
bisphenoxyalkane having two or three carbon atoms in the alkane moiety with a
stoichiometric excess of bromine chloride in the presence of a Lewis acid cat-
alyst and a chemically inert organic solvent adapted to dissolve all of such
compounds. Optionally, the bisphenoxyalkane and resulting product of the pro-
cess may have alkyl and chlorine substituents in either or both phenyl groups.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for polybrominating bisphenoxyalkanes
without substantial cleavage of either phenoxy-to-alkylene
linkage, comprising reacting a bisphenoxyalkane having the
formula:
<IMG>
in which A is alkylene of two or three carbon atoms, R is
alkyl up to and including four carbon atoms and X is 0, 1 or
2, with a stoichiometric excess of bromine chloride in the
presence of a catalytic amount of a Lewis acid catalyst and
a chemically inert organic solvent adapted to dissolve all
of said compounds to form a product having the formula:
<IMG> (I)
in which A, R and x are as defined above; y is: 3, 4 or 5;
and z is 0, 1 or 2.
2. The process of claim 1 in which said bromine chloride
consists of bromine and chloride in a molecular ratio of from
0.7:1 to about 1.3:1, respectively.
3. The process of claim 1 in which said bromine chloride
consists of bromine and chlorine in a molecular ratio of from
about 0.9:1 to about 1.1:1, respectively.
12

4. The process of claim 1 in which said Lewis acid
catalyst is a metal halide Lewis acid catalyst capable of
effecting a Friedel-Crafts reaction.
5. The process of claim 1 in which said Lewis acid
catalyst is selected from the bromides and chlorides of
aluminum, iron, antimony, and mixtures thereof.
6. The process of claim 1 in which said Lewis acid
catalyst is a metal halide selected from the group consisting
of SbCl3, SbCl5, FeCl3, AlCl3, TiCl4, TiBr4, SnCl2, SnCl4,
SnBr4, AlBr3, BeCl2, CdCl2, ZnCl2, BF3, BCl3, BBr3, GaCl3,
GaBr3, ZrCl4, BiCl3, UCl4, and SeCl4.
7. The process of claim 1 in which said chemically
inert organic solvent is a chlorinated aliphatic hydrocarbon
having no carbon to carbon unsaturation.
8. The process of claim 1 in which said chemically
inert organic solvent is selected from the group consisting
of carbon disulfide, nitromethane, nitroethane, carbon
tetrachloride, chloroform, tetrachloroethane, methylene
chloride, trichloroethane, and dibromoethane.
9. The process of claim 1 in which said reaction is
carried out at a temperature within the range of about minus
10°C to about 150°C.
10. The process of claim 1 in which said reaction is
carried out at a pressure of about atmospheric pressure to
about 200 psig.
11. The process of claim 1 in which bisphenoxyethane
is reacted with bromine chloride to give bis (pentabromophen-
oxy) ethane.
13

12. The process of claim 1 in which said excess of bromine
chloride is from about 5% to about 50% molar excess of said
bisphenoxyalkane.
13. The process of claim 1 in which said chemically
inert organic solvent is substantially anhydrous.
14. The process of claim 1 in which said Lewis acid
catalyst is a relatively strong metal halide Lewis acid,
water is added to the solvent after formation of said product,
said water destroying the effect of the relatively strong
catalyst, and including the step of recovering the product by
distilling off said solvent and water.
15. The process of claim 1 in which said Lewis acid
catalyst is a relatively weak metal halide Lewis acid, and
including the step of recovering the product by distilling
off said solvent.
16. The process of claim 1 in which said catalyst is
present in an amount of from about 5% to about 25% by weight
of the bisphenoxyalkane.
17. A process for polybrominating bisphenoxyalkanes
without cleaving either phenoxy-to-alkylene linkage, comprising
reacting a bisphenoxyalkane having the formula
<IMG>
in which A is alkylene of two or three carbon atoms, R is
alkyl up to and including four carbon atoms and x is 0, 1 or 2,
with a molar excess of about 5% to about 50% of bromine chloride
14

consisting of bromine and chlorine in a molecular ratio of
from about 0.7:1 to about 1.3:1, respectively, in the presence
of a catalytic amount of a metal halide Lewis acid catalyst
capable of effecting a Friedel-Crafts reaction and in the
presence of a chemically inert chlorinated organic solvent
adapted to dissolve all of said compounds, said reaction
being carried out at a temperature within the range of about
minus 10°C to about 150°C and at a pressure from about
atmospheric pressure to about 200 psig. to provide a yield of
at least 77% of a product having the formula:
<IMG>
in which y is 3, 4 or 5; and z is 0, 1 or 2.
18. The process of claim 17 in which said bromine chloride
consists of bromine and chlorine in a molecular ratio of from
about 0.9:1 to about 1.1:1, respectively.
19. The process of claim 17 in which said product is
bis (pentabromophenoxy) ethane.
20. The process of claim 17 in which said chemically
inert organic solvent is substantially anhydrous.
21. The process of claim 17 in which said Lewis acid
catalyst is selected from the bromides and chlorides of
aluminum, iron, antimony, and mixtures thereof.

22. The process of claim 17 in which said chemically
inert organic solvent is a chlorinated aliphatic hydrocarbon
having carbon to carbon saturation.
23. The process of claim 17 in which said catalyst is
present in an amount of from about 5% to about 25% by weight
of the bisphenoxyalkane.
16

Description

10872~1
Highly brominated aryl alkyl ethers have utility as fire retardants
for organic, polymeric resinous materials. As a general rule, the more bromin-
ation that can be achieved in the aryl group, the more effective the compound
is as a fire retardant. Heretofore it has been difficult to brominate to as
much as three bromine atoms per phenyl group in bisphenoxyalkanes, and most
difficult if not impossible completely to brominate the phenyl group, without
cleaving one or both phenoxy-to-alkylene linkage in such bisphenoxy compounds.
For example, if elemental bromine is used as the brominating agent,
hydrogen bromide is produced as a by-product and this degrades the product
formed. Previously, the use of Lewis acids as catalysts for the bromination
also resulted in degradation of the product. In both instances, cleavage of
the phenoxy-to-alkylene linkage occurred. Hydrogen bromide caused the forma-
tion of phenols and Lewis acids promoted the formation of phenol salts. For
example, when anisole is heated for two hours at 100C with aluminum chloride,
methyl chloride evolves and leaves behind C12AlOC6H5 (G. Beddeley, J. Chem.
Soc. 1944, 330). When the bromination of anisole is catalyzed by aluminum
chloride (Bonneaud, Bull. Soc. Shim., Fr. (4) 7,776), or iodine (A. I. Hashem,
J Appl. Chem. Biotechnol, 24, 59, 1974) only pentabromophenol is recovered.
Thus, anisoles cannot survive drastic bromination conditions.
Accordingly, a dilemma faces one seeking the production of highly
brominated aryl alkyl ethers. If conditions conducive to substantial bromina-
tion are used, such as strong Lewis acids and relatively high temperatures,
then degradation and cleavage of the phenoxy-to-alkylene linkage in the pro-
duct results. If, to avoid this, milder conditions are used, such as no cata-
lyst or a weak Lewis acid catalyst and relatively low temperatures, then an
unsatisfactory, low level of bromination results.
It would, therefore, advance the art to be able to produce highly
brominated bisphenoxyalkanes, especially at relatively high yields, in a man-
ner which does not degrade the product nor cleave the phenoxy-to-alkylene
linkage.
.
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1~7~11
According to th.e present invent~on there is provided
a process for polybrominating bisphenoxyalkanes without
substantial cleavage of either phenoxy-to-alkylene linkage,
comprising reacting a bisphenoxyalkane having the formula:
( ~ O - A - O - ~ ~
in which A is alkylene of two or three carbon atoms, R is
alkyl up to and including four carBon atoms and X is Q, 1 or 2,
with a stoichiometric excess of bromine chloride in the presence
of a catalytic amount of a Lewis acid catalyst and a chemically
inert organic solvent adapted to dissolve all of said compounds
to form a product having the formula:
R R
Bry ~ ~ Y (I)
in which A, R and x are as defined above; y is 3, 4 or 5; and
z is Q, 1 or 2.
Thus, a bisphenoxyalkane having two or three carbon
¦ atoms in the alkane moiety is polybrominated with a stoichio-
metric excess of bromine chloride in the presence of a Lewis
acid catalyst and a chemically inert organic solvent adapted
~, to dissolve all of the compounds. A product is formed having
the formula (I) above. It is understood that each of R, x,
,~,
L'~ 2
.~ ~,

~L0872~1
y and z may be the same or different on the phenyl groups.
Preferably the Lewis acid catalyst is a metal halide
Lewis acid catalyst capable of effecting a Friedel-Crafts
reaction, and the chemically inert organic solvent is a
chlorinated aliphatic hydrocarbon. In general, solvents having
no carbon to carbon unsaturat;`on are preferred. The process
may be carried out at a temperature within the range of about
minus 10C to about 150C and at a press~re of about atmospheric
to about 200 pounds per square inch gage (:psig~. ~ields of
at least 77% of the product are possi`ble, and yields of 90%
and higher are common. The preferred product of the process
is bis (pentabromophenoxyl ethane.
-2a-

1087~11
The process includes the use of both relatively strong and relative-
ly weak Lewis acid catalysts. ~hen relatively strong Lewis acid catalysts are
used, water is added to the solvent to destroy the catalyst after formation of
the product and prior to recovering it.
Considering in greater detail the components and conditions of the
present process, only those bisphenoxyalkanes having two or three carbon atoms
in the alkane moiety are useful. Such alkanes with one or more than three car-
bon atoms have been found still to cleave at the phenoxy-to-alkylene linkage.
Bisphenoxyalkanes charged to the process may have alkyl and chloro substituents
as shown, for example, by Formula 1 of the preceding section. Similarly, some
bromination may or may not be present in the material charged, although of
course not to the extent capable of being achieved by the present process.
The brominating agent is bromine chloride by which is meant a mix-
ture of chlorine and bromine. Bromine chloride is probably an equilibrium
mixture of bromine, chlorine and bromine chloride. Desirably, bromine chlor-
ide is used in an anhydrous system. The bromination proceeds to the virtual
` exclusion of chlorination, Most or all of the chlorine present in the bromin-
ating agent is converted to HCl which escapes as a gas. Use of bromine chlor-
ide as the brominating agent is thought to be highly contributory to avoiding
the phenoxy-to-alkylene cleavage. Bromine chloride enables the process to
proceed under milder conditions, such as a lower temperature, than otherwise
would be the case when bromine alone is used. Indeed, the present process
proceeds at room temperatures. Bromine chloride also enables the use of less
strong Lewis acid catalysts which fu~ther contributes to avoiding the cleavage
of phenoxy-to-alkylene linkage.
The manner of preparing bromine chloride is known in the art. Con-
veniently, bromine and chlorine are mixed in a closed container and the bro-
~, mine chloride formed is withdrawn from the liquid phase. Bromine and chlor-
ine may be used in a molecular ratio of from about 0.7:1 to about 1.3:1 and
30preferably from about 0.9:1 to 1.1:1, respectively. If the ratio of bromine
~' ,
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1~7Z~l
to chlorine substantially exceeds that indicated, the process is operational
but HBr is formed as a by-product. HBr is more valuable than HCl, so tha~ evo-
lution of HBr in this manner is a waste. If the ratio of bromine to chlorine
is substantially lower than that indicated, chlorination of the bisphenoxyal-
kane proceeds to a substantial extent and hampers realization of the desired
amount of bromination. Preferably, bromine and chlorine are used in about a
1:1 molecular ratio. Any stoichiometric excess of the bromine chloride over
the bisphenoxyalkane is effective to encourage short reaction periods and com-
plete conversion. As a rule, the excess of bromine chloride over the bisphen-
oxyalkane is from about 5% to about 50% molar excess of the alkane.
Lewis acid catalysts in general, such as iodine, are useful in cata-
lyzing the process. However, the desirable Lewis acid catalysts are the metal
halides capable of effecting a Friedel-Crafts reaction. Of these the preferred
ones are the bromides and chlorides of aluminum, iron, antimony, and mixtures
thereof, antimony chloride being the most preferred. Specific examples of
metal halide Lewis acid catalysts include SbC13, SbC15, FeC13, AlC13, TiC14,
TiBr4, SnC12, SnC14, SnBr4, AlBr3, BeC12, CdC12, ZnC12, BF3, BC13, BBr3, GaC13,
GaBr3, ZrC14, BiC13, UC14, and SeC14.
It will be noted that boron is considered as a metal in accordance
with the authority "Hackh's Chemical Dictionary", Fourth Edition, 1969, page
107. It is understood that any of the indicated metals, such as iron, may be
added directly to the reaction mixture in elemental form, the metal reacting
with th0 bromine or chlorine of the bromine chloride to form the catalyst.
When this procedure is followed, the amount of bromine chloride employed can
be adjusted to account for the reaction.
A catalytic amount of the catalyst is used which can be readily de-
,j termined by trial and error. The amounts of catalyst and bromine chloride em-
ployed appear to be interrelated in that decreasing the amount of catalyst re-
quires an increase in the amount of bromine chloride to obtain substantially
the same amount of bromination and vice versa. However, as a general rule,

1~87211
the catalyst used may range in amount from about 5% to about 25%, and prefer-
ably from about 15% to about 20%, by weight of the bisphenoxyalkane.
Both relatively weak and relatively strong Lewis acid catalysts may
be employed in the present process. The relatively weak or mild Lewis acids
such as SbC13, SbC15, SbBr3, SnC14, and TiC14 are preferred. However, rela-
tively strong Lewis acids, such as AlC13, FeC13, AlBr3, FeBr3, and BC13 can be
used if the Lewis acid is destroyed before the product is recovered from the
reaction mixture. This can be effected by adding water to the mixture after
the bromination step and before the product is recovered. The water destroys
the effect of the strong Lewis acid catalyst. The product is ultimately re-
covered by distilling off the bromine chloride, organic solvent and the water
where that has been added. If a strong Lewis acid is not destroyed, some of
the product is converted to tarry materials during distillation. This safe-
guard of destroying the catalyst can be followed even where relatively wea~
Lewis acid catalysts are used. If water is not added to destroy the catalyst,
the product can be recovered by other techniques, such as filtering the reac-
tion mixture and washing and drying the residue.
The organic solvent must dissolve the indicated components of the
reaction mixture and be inert toward them. Organic solvents free of carbon
to carbon unsaturation have been found suitable for this purpose and especial-
ly carbon to carbon saturated chlorinated aliphatic hydrocarbons. Carbon satu-
ration in the solvent is needed primarily to resist halogenation. However,
the solvent need not be chlorinated. Specific useful solvents include: car-
bon disulfide, nitromethane, nitroethane, carbon tetrachloride, chloroform,
tetrachloroethane, methylene chloride, trichloroethane, dibromoethane, and
the llke. Preferably, the solvent is substantially anhydrous. Water appar-
ently destroys the catalyst and causes the reaction to proceed at a slower
rate. As used here and in the claims, the term "solvent" includes one of the
reactants itself which has the described requirements of the solvent. For
example, bromine chloride in excess can itself serve as the solvent.
-- 5 _

~087211
In carrying out the present process, the solvent is first charged to
a reaction vessel, followed in any sequence by the bisphenoxyethane and Lewis
acid catalyst, and finally the bromine chloride. The brominating agent may be
formed in situ or just prior to introduction into the reaction vessel by meter-
ing together streams of gaseous bromine and chlorine. However, it is preferred
to use preformed bromine chloride which promotes faster equilibrium and mini-
mizes side reactions. The rate of adding bromine chloride is not critical as
long as a stoichiometric excess is present at least at the end of the reaction
to encourage as complete a bromination as possible. As an example, a stoichio-
metric excess of bromine chloride can be added to the bisphenoxyalkane over aperiod of time from abou~ 30 minutes to 4 hours.
Process conditions for the liquid phase reaction likewise are not
critical with the exception that subatomospheric pressures which introduce ad-
verse effects should not be used. Otherwise, the pressure can range from about
atmospheric pressure virtually to the physical limits of the apparatus and, as
a practical matter, to about 200 psig. Pressures of about 50 psig. to about
100 psig. are preferred. If the reaction is confined, the pressure will in-
crease since it is autogenous. If desired, the pressure of the reaction ves-
sel can be relieved from time to time to a minor extent by venting without af-
fecting adversely the bromination reaction. The higher pressures tend to de-
crease the excess of bromine chloride needed.
Likewise, although temperature is not critical, the temperature of
' the process can range from about minus 10C to about 150C, with temperatures
from about room temperature to about 50C being preferred. The reaction is
i completed within about two hours to about to as many as about twenty hours,
depending on conditions and reactants. Yields of at least 77% of the product
are obtained, and yields within the range of about 93% to about 98% are fre-
quently reached.
The class of compounds obtained as products by the present invention
; 30 has been previously indicated by Formula 1. A desired class of compounds ob-
.,~ .
,, ,
~ ~ !
:! - 6 -

- :~L087211
tained by the process has the formula:
Bry Br
~ 0 - C2H4 0 - ~ (II)
Cl Cl
z z
in which y is 3, 4, or 5; and z is 0, 1, or 2 and in which x, y, and z may be
the same or different. The preferred product is bis (pentabromophenoxy)
ethane.
The following Examples only illustrate the invention and should not
be construed as imposing limitations on the claims.
EXAMPLE 1
When 1,2-diphenoxyethane is treated with bromine under conditions
10 using an iron catalyst and a temperature of 90 C. in the presence of an
organic solvent, a yield of 90% of pentabromophenol is obtained. When the
diphenoxyethane is treated with bromine under mild conditions, that is, with
antimony trichloride catalyst at room temperature, the product 1,2-bis (di-
bromophenoxy~ ethane is produced. Thus, in the second reaction, some brom-
~ ination occurred Wit]lOUt cleavage of the phenoxy-to-alkylene linkage, but
j the bromination was relatively small and consisted of only two bromine atoms
on each phenyl group. When the temperature for the second reaction was in-
creased to 90C., a complex mixture of a number of products was obtained
which did contain some 1,2-bis (tribromophenoxy) ethane.
However, when the diphenoxyethane was treated in accordance with
the present invention, namely, at room temperatures in the presence of anti-
mony trichloride or aluminum trichloride with an organic solvent having car-
bon to carbon saturation and containing a stoichiometric excess of bromine
chloride in substantially equimolecular amounts, a yield of 93% was obtained
of 1~2-bIS (pentabromophenoxy) ethane.
EXAMPLE 2
The following is a complete working example of one form of the pres-
.,
~ _ 7
.
., .

721~
ent process. To prepare bromine chloride, an amount of 106.5 grams of tetra-
chlorethane as a solvent was charged into a 200 ml flask and cooled to a tem-
perature within the range of 0 to about 5C while stirring. Bromine was then
added in an amount of 53.2 grams followed by an addition of 31.2 grams of
chlorine via a gas sparger at the rate of 11 grams per hour. In another flask,
127.5 grams of tetrachloroethane and 8.6 grams of 1,2-diphenoxyethane were
charged and dissolved with stirring. This solution was filtered to remove a
small quantity of insolubles. Antimony trichloride was then added in an a-
mount of 1.2 grams as the Lewis acid catalyst.
The filtrate and catalyst were added to a reaction vessel to which
167.6 grams of bromine chloride solution, prepared as initially described,
were uniformly added over a period of about three hours while maintaining the
solution at a temperature of about 18C to about 30C. The solution was then
stirred for another three hours at room temperature.
Two factors control the rate of addition of bromine chloride, name-
ly, the ability to control the exothermic reaction and the need to minimize
the loss of the brominating agent with escaping HCl. The bromination involves
the electrophilic substitution of a bisphenoxyalkane without breaking the
phenoxy-to-alkylene linkage. Bromine chloride allows the reaction to be run
under relatively mild conditions ~room temperature and lower) in the presence
of a weak Lewis acid catalyst, such as antimony trichloride or antimony penta-
halide, which do not degrade the product in boiling tetrachloroethane (147C).
At the same time, bromine chloride offers an economic advantage over the use
of bromine alone. The present process eliminates the problem of oxidi~ing hy-
drogen bromide~ given off as ef~uent from prior brominating processes, back
to bromine and then recycling bromine as the brominating agent.
I' Following the reaction which produces the polybrominated product, ~ .
the reaction mixture was heated sufficiently to distill off excess bromine ~ -
chloride together with some solvent into a standard laboratory trap which con- ~ -
~ained the same solvent as used for the reaction. During the distillation,
.
,
` : -
., , . :

10~7211
the still head temperature increased gradually to that of the solvent, about
147C. The distillation was stopped when a total of 60 ml was accumulated in
the trap. At this stage, there was no more bromine or chlorine in the reac-
tion vessel. The absence of red vapors in the reaction vessel or still head
can be taken as the end point of the distillation. The reaction mix was then
cooled to room temperature and filtered, followed by a wash of the residue
with 128 grams of tetrachloroethane which was again filtered. During this op-
eration, the solvent should be protected from water as it still contains ac-
tive catalyst.
The residue of these filtering steps was oven dried at about 100C
to obtain the final product. Yields from this procedure range from about 92%
to about 94% and higher. The product had a melting point of 312C to 316C
and was white to off-white in appearance.
In place of the catalyst, solvent, and other reactants indicated,
any of the previously disclosed corresponding components could have been used.
EXAMPLE 3
A solution was made of 65 ml. of 1,1,2,2-tetrachloroethane, 8.6 grams
(0.04 mole) of diphenoxyethane and 0.25 ml of antimony pentachloride. The sol-
ution was cooled in an ice bath and to it was added, over 30 minutes, a solu-
tion containing 53 grams of 1,1,2,2-tetrachloroethane, 26.9 grams of bromine
, (0.34 gram atoms) and 13.4 grams of chlorine (0.38 gram atoms). The mixture
was stirred in an ice bath for 40 minutes and then for 2 1/2 hours at room
temperature. An amount of 29.4 grams of a solid having a melting point of
212C - 218C was collected which contained 72.4% bromine.
EXAMPLE 4
A solution was made by adding 432 grams (5.4 gram atoms) of bromine,
211 grams (5.9 gram atoms) of chlorine and 22 ml. of antimony pentachloride
to 540 ml of 1,1,2,2-tetrachloroethane. Another solution was made by dis-
, solving 77.4 grams (0.36 mole) of 1,2-diphenoxyethane in 260 ml of 1,1,2,2-
tetrachloroethane. The halogen solution was cooled in an ice bath and the
:,-
:~ _ g _
.
.
i~ ` ' . ~ .

~0~72~1
diphenoxyethane solution added to it over 37 minutes. The solution was then
stirred 15 minutes in the ice bathJ next at room temperature for two hours,
and then left overnigh~. A precipitate formed was filtered, washed free of
halogen first with 1,1,2,2-tetrachloroethane and then with methanol and finally
dried. An amount of 345.7 grams of product of melting point 316-319C was ob-
tained (95.3% yield based on decabromodiphenoxyethane).
EXAMPLE 5
The amounts used in this example were 4.3 grams (0.02 mole) of di-
phenoxyethane, 21.7 ml of tetrachloroethane, 0.6 grams of aluminum chloride
and 0.30 mole of bromine chloride in 30 ml of tetrachloroethane.
The bromine chloride solution was added over 1 hour, 38 minutes, to
the ice cooled diphenoxyethane. The mixture was then heated for 1 hour at 40C,
after which 10 ml of water was added and the mixture stirred at room tempera-
ture for 30 minutes. The excess bromine chloride was distilled off. The sol-
vent was then steam distilled to leave a product slurry in water. The water
was made into 5 normal hydrochloric acid by adding concentrated hydrochloric
acid, and the slurry refluxed for an hour, filtered and washed with water. An
amount of 19.3 grams of a solid having a melting point of 308-313C was ob-
tained, (96% yield based on decabromodiphenoxyethane).
EXAMPLE 6
.
A solution was made of 178.5 grams of 1,1,2,2-tetrachloroethane, 9.69
grams (.04 mole) of 1,2 bis (o-tolyloxy) ethane and 1.82 grams (0.008 mole) of
antimony trichloride. The solution was cooled in a water bath and to it was ;~
added over the next 120 minutes a solution containing 77.5 grams 1,1,2,2-tetra- ;
chloroethane, 38.4 grams of bromine (0.48 gram atom) and 17.3 grams chlorine
(0.49 gram atom). The mixture was then stirred for 120 minutes at room tem-
perature. The excess bromine chloride was distilled off and the mixture fin-
ally cooled and filtered. An amount of 24.3 grams of a solid having a melting
point of 218-246C was recovered. The solid contained 70.8% bromine and repre-
santed a yield of 69.6% based on 1,2 bis (o-tolyloxy tetrabromo) ethane.
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:~087211
While the foregoing describes several embodiments o the present
invention, it is understood that the invention may be practiced in still
other forms within the scope of the following claims.
~,
. .
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