Note: Descriptions are shown in the official language in which they were submitted.
~f~
Substantially non flammable biologically
degradable functional fluid
The invention relates to a substantially non-flammable,
biologically degradable functional liquid, particularly
a hydraulic fluid or an insulating fluid for electrical
apparatus, which comprises a bromine containing benzyl-
toluene derivative as the essential component.
Chlorinated aromatic compounds, particularly chlori-
nated biphenyls, have taken an important place in various
fields of technology in the last few decades. The poly-
chlorinated biphenyls, in particular, have been used to
a large extent as hydraulic fluids r as insulating fluids
for electrical equipment and as flame suppressing addi-
tives for plastics and the like. However, in the last
few years, these compounds have been the subject of
considerable dispute. It has been determined that
these products exert harmful effects on health and the
environment and they have potentially catastrophic
dangers in that, when burned, highly poisonous dioxin
and dibenzofuran may be formed. This has already lead
in part to the complete banning of the manufacture or at
least the ~se of such compounds by the state supervisory
organizations and in part to the imposition of serious
limitations to the use of these substances.
To overcome these disadvantages it has been proposed
in European Patent No. 88 650 granted September 14, 1983
to use instead chlorinated benzyltoluenes and chlorinated
benzylxylenes as lubricants and also as hydraulic fluids
because these compounds are substantially inflammable and
resist oxidation and are also biologically degradable and
are advantageous in view of their low toxic properties.
GB-PS 1 504 655 granted March 22, 1978 describes
electrical equipment which contains biologically easily
degradable dielectric fluids, namely halogina~ed diphenyl-
methane, which are characterized in that the halogensubstituents and possibly alkyl substituents are located
only in one of the two phenyl rings, while the other phenyl
ring remains ùnsubstituted, since only such haloginated
diphenylmethanes having an unsubstituted phenyl group are
easily biologically degradable, while the diphenylmethanes
substituted on both phenyl residues are resistant to
microbiological degradation.
European Patent No. 8251 granted February 20, 1980
discloses fluid dielectrics which can be used, for example,
as insulating ~luids for transformers or as impregnating
materials for insulating layers using capacitors. It is
concerned with alkyl aromatic compounds which are chlor-
inated on the aromatic nucleus and which may be obtained
from chlorotoluene and/or chloroxylene, for example tetra-
chlorobenzyltoluene, and it is indicated that these com-
pounds have advantages over the multichlorinated biphenyls
previously used for the same purpose. The absence of the
biphenyl nucleus and the presence of the alkyl groups on
the aromatic nucleus are accordingly credited with the
favourable action on the biological degradative behaviour.
Finally, European Patent No. 71 338 granted February 9,
1983 describes electroviscous fluids which consist of hydro-
phobic liquids in which solid hydrophilic particles are
dispersed. Upon application of an electrical field to such
a suspension the viscosity of this mixture rises drastic-
ally. This change is reversible and rapid so that such
suspensions can be used, for example, in
electronically controllable clutches. It is indicated
that the hydrophobic liquids in the mixture have a high
boiling point, a low viscosity, suitable electrical
properties and chemical stability and low toxicity and are
preferably biologically degradable. For this purpose,
according to this European Patent Application, halogenated
diaryl derivatives are suitable as the hydrophobic fluids,
the aromatic nuclei of which are combined with one another
via various bridges and have fluorine, chlorine or bromine
atoms as the halogen substituents. It is stated that these
diaryl derivatives should be asymmetrically substituted
because then a lower solidification point of the fluid and
an improvement of the ability to be biologically degraded
is obtained.
The conventional functional liquids are not satis-
factory in all respects because they either do not fulfil
the criterion of non-flammability required by hydraulic
and insulating fluids or they have disadvantageous pro-
perties resulting from their inflammability such as poor
biodegradability, toxicity of the fulids or their decom-
position products, unfavourable viscosity-temperature
properties or incompatibility with sealing elements.
The object of the present invention is to provide a
functional fluid which has physical properties necessary
for the intended use and while having high chemical sta-
bility nevertheless can be biologically degraded and is
nontoxic and does not give rise to highly toxic products,
such as dioxin for example, upon improper treatment.
It has been surprisingly found that a particular group
of halogenated diaryl derivatives not only, on the one
hand, exhibits valuable technical properties, but also,
on the other hand, does not exhibit the dangerous and the
environmentally hazardous properties of the conventional
compounds, so that the compounds are especially suitable
as or for functional fluids.
The invention provides a non-flammable biologically
-- 4 --
degradable func~ional fluid consisting of or containing at
least one bromine containing benzyltoluene derivative of
general formula I~
(CH~) (CH3)z~
(Cl)~, (I)
(Br)x (Br)x,
in which x is 1 or 2,
x' is 0 or 1,
y is 0, 1 or 2,
y' is 0, 1 or 2,
~ is 0, or 1, and
zl is 1 or 2
with the proviso that the relationship
y + y' = 0, 1 or 2 and
x ~ xl ~ y + y' = 1, 2 or 3
is fulfilled.
~.rhe bromine-containing benzyltoluene derivatives used
according to the invention as or in functional fluids are
thus compounds whiah are substituted on both nuclei wherein
at least one bromine substituent and one methyl group must
be present. Both the nuclei can however carry several
bromine atoms and several methyl groups and the positions
of these substituents are not important so that, according
to the invention, all of the positional isomers of these
bromine-containing benzyltoluene derivatives of formula I
given above can be used in or as functional fluids.
In addition one or both of the phenyl groups may
contain chlorine atoms as substituents.
It has surprisingly been found that these bromine-
containing benzyltoluene derivatives used according to the
invention possess a more advantageous compatibility with
; 30 the environment than ~he conventional halogenated diaryl
derivatives, and at the same time possess excellent
-- 5 --
physical properties which make them particularly suitable
for use as functional fluids such as hydrulic fluids or
insulating fluids for electrical equipment.
Surprisingly, it has also been found that the
substituted bromine-containing benzyltoluene derivatives
of the invention of general formula I given above, which
are substituted on both phenyl rings, can be biologically
degraded without further treatment which appears sur-
prising in view of European Patent No. 71 338
and GB-PS 1 504 655 discussed above. Moreover, the
bromine-containing benzyltoluene derivatives of general
formula I above used in accordance with the invention have
the further surprising advantage that in normal working
conditions they are fluid and exhibit a particularly
favourable viscosity-temperature relationship. Moreover
they possess a high flame point, are of low toxicity and
low corrosiveness and do not produce highly toxic dioxin
products when improperly overheated, which can occur
accidentally in the case of polychlorinated biphenyls.
Moreover it has been found that the bromine-containing
benzyltoluene derivatives used according to the invention
are compatible with sealing elements to an excellent
extent, so that the group of compounds of the invention
have unexpectedly proved advantageous for the uses
discussed above.
Particularly preferred are substantially non-flammable,
biologically degradable functional fluids which, as the
bromine-containing benzyltoluene derivatives, contain a
compound of general formula II
(CH3)z tCH3)z.
~ CH2 ~ (II)
Br (Br)x,
in which x' is O or 1, z is O or 1 and z' is 1 or 2.
- 6 ~
Even more preferred are functional fluids according
to the invention which contain a bromine-containing
benzyltoluene derivative according to formula III, IV
or V below.
~ CM2 ~ (III)
Br Br
~H3CH3
CH2 ~ (IV~
Br CH3
CH3
CH2- ~ (V)
Br
Na~urally the functional fluids according to the
invention may contain the bromine-containing benzyltoluene
derivatives defined above alone, but preferably however
they are used in the form of mixtures, especially in the
form of mixtures of the individual positional isomers of
these compounds.
The bromine-containing benzyltoluene derivatives
according to the invention of the formulae given above
and used in the invention in or as functional fluids are
partially known, for example in the general formula of
European Patent No. 71 338 mentioned above and also in the
generic definition of DE-OS 23 36 289 published 1975. The
former reference discloses an enormously large group of
compounds, and mentions the use of the invention neither
expressly nor in the examples. DE-OS 23 36 289 describes
essentially chlorinated o-benzyltoluene, which is described
as a valuable starting material for the preparation of
anthracene and anthraquinone and its derivatives. The
'; compounds of the invention of the general formula given
above and their uses differ from the biologically
degradable bromine-containing benzyltoluene derivatives
described in GB-PS 1 504 655 in that they are not just
asymmetric but rathe are substituted on both phenyl rings
and nevertheless surprisingly have advantageous properties.
The preparation of the bromine-containing benzyltoluene
derivatives of the invention takes place in a conventional
manner either by the halogenation of the,non-halogen
substituted corresponding benzyltoluene with elemental
bromine or a mixture of bromine and chlorine in the
presence of a known halogenation catalyst such as iron,
FeC13, FeBr3, AlC13, ~iC14 and the like. In this
way the reaction can take place at room temperature or,
depending on the catalyst employed, at temperatures
between -5 and ~40C.
A further preferred method for the preparation of
the bromine-containing benzyltoluene derivatives of
the invention of general formula I above involves the
condensation of a compound of general formula VI
(CH3~zl
~ (VI)
(Cl)
(Br~x,,
in which x', y' and z' are as disclosed above, with a
compound of general formula VII
1~
- 8
(CH3)z
~ (Cl)y (VII)
Hal-CH2~-~
(Br)x
in which Hal represents bromine or chlorine and x, y, z
are as disclosed above. The condensation can be carried
out, if necessary, in the presence of a Friedel-Crafts
5catalyst, such as FeC1~, FeBr3, AlC13 and/or TiCl4,
in the presence of an excess of the compound of general
formula VI.
The bromine-containing benzyltoluene derivatives
according to the invention exhibit a substantially
improved flame resistance than the chlorine substituted
compounds known from European Patent Application No.
88 650 while at the same time exhibiting improved
viscosity-temperature relationships.
The known asymetrically substituted dibromobenzyl-
toluene of GB-PSl 504 655 are solid at room temperature,
while the isomer brominated on both phenyl rings
solidifies at -25C, which is particularly advantageous
when using these compounds as hydraulic fluids or
insulating fluids.
The bromine-containing benzyltoluene derivatives of
the invention have proved useful not only as hydraulic
fluids but also as insulating fluids for electrical
equipment, such as for example condensers, transformers
and the like, not only on the basis of their favourable
viscosity-temperature relationships, but also on account
of their very favourable flame resisting effect. The
functional fluids of the invention can in consequence of
this be used, in particular, as non-flammable hydraulic or
insulating fluids which, on the basis of their low
toxicity, their low inclination to form poisonous de-
composition products and their biological degradability,
.~
- 9 -
represent a considerable contribution to technology.
As already explained the bromine-containiny
benzyltoluene derivatives mentioned above can be contained
individual'~y or also in the form of mixtures, preferably
in the form of isomer mixtures, in the functional fluids
of the invention instead of being used alone as said
fluids.
The invention is described in more detail in the
following examples.
Preparation Example
Preparation of dibromobenzyltoluene by condensation of
bromotoluene with bromobenzylbromide.
For the preparation of dibromobenzyltoluene, bromo-
toluene was first prepared by the bromination of toluene
with elemental bromine in the presence of anhydrous
FeC13, and this was then brominated at the side chain.
With this 8.3 Mol of bromotoluene were heated in
the presence of 0.5g of a radical chain initiator
~ zobisisobutyronitrile) to a temperature of 80C.
1.66 Mol of bromine were added drop-wise with cooling
under irradiation with an ultra-violet lamp having a
power of 300 W. The resulting hydrogenbromide was
absorbed in a wash bottle containing cooled water.
The cooled mixture was then dropped into a suspension
of 6g FeC13 in 1.6 Mol of bromotoluene at a temperature
30C to bring about the condensation reaction. The re-
sulting gaseous hydrogenbromide was absorbed into cooled
water in a wash bottle in the same manner as described
above. The formation of by-products (brominated dibenzyl-
toluene), was suppressed during this condensatlon reaction
by the presence of a large excess of bromotoluene.
After the termination of the addition the mixture
was heated to 50C for 30 minutes, after which the cooled
reaction mixture was washed with one liter of water,
then with one liter of 10~ sodium hydroxide solution and
finally once again with one liter of water. The organic
-- 10 --
phase was dried and the excess bromotoluene was distilled
off.
The remaining fluid was distilled under 0.4 mbar, and
395g of a main fraction boiling between 155 and 166C at
0.4 mbar was obtained and this was identified by mass
spectrometry as dibromobenzyltoluene. Thereby an
investigation of the isomers was foregone.
The electron stream mass spectrum of the resulting
dibromobenzyltoluene is given in the Table below.
, :
TAB LE
Electron Impact Mass Spectr~m of Dibromobenzyltoluene
m/x Relative Tot~l lon Intensity m/x Relative Totdl Ion Intenslty
Int~nsity(~) Stream(o) Intensity(~) Stream(~)
IS,ool,os 0,05 118133,00 0,7d ' 0,07 94
37,003,65 0,~4~0 139,00 3,19 0,~ 445
~-,00I ~o o,ll IS7~O,oo 0,93 0,01 Il~
3g,0012,4B 1,10 1506141,C0 0,70 0,06 g4
sO~oo9,~3 0,52 ~2~14~,oo 0,69 0,06 83
S~.00~,2~ 1,03 1476lSO,Oo ~,o~ o,lB ~/13
52,00~,62 0,23 316151,00 4,t~ 0,41 S30
S~,oO1,75 o,ls 211152,00 ~,41 0,74 IOIS
t1,001.96 0,17 ~36~S3,U0 ~,~4 0,20 ' 270
t~,00~,91 0,s2 713163,00 4,~9 o,~7 sos
61,00~7,97 ~,5a ~60164,00 s,o~ 0,44 60S
64,0~4,9~ 0,44 601165,00 IOo,oo 0,79 1~06~
6S,00~ 93 0,~6 ~s~1~6,00 14,41 1,~7 1731
~9 000 ~7 0,0~ 1OS167,00 I,z~ 0,~ 7
74.004,95 0,44 s9~~69,00 8,s~ 0,7s ~o~o
75 0010 79 0,9S 1~0~170,00 1,4~ 0,13 172
7~,003S,01 3,01 42~4171,00 7,~ 0,69 94~
71,oo14,y7 I,3z IR06175,00 0,5t 0,OS 75
71,00S,46 0,4d 659176,00 6,45 0,s7 779
79,001,l~ o,lo 1~6~71,00 5,88 0,5~ 709
91 002, 6~ 0, ~4 J~4 1 79, 00 32, 56 ~, 86 3~23
1~,007,07 0,6~ ~5~179,00 46,55 4.09 5616
.00 3,61 0,01 321~0,00 76,1~ 6,69 9114
~5 000,7~ 0,06 allal,oo ll,as l,OS 14~4
16,001,91 o,l7 2381~2,00 IS,63 1,37 1886
~7,003,~6 0,3~ ~s41a3,ao S,10 0,qS 615
1~2,00 16,00 1,411930 114,00 14,79 1,30 17B4
as,;70 8~,79 7,8310132 105,00 4,~0 o 43 591
90,003a~.s9 3,~9 465C~43,00 1,42 o,l~ 17~
91,oo ~ o,I9 ~S6~44,oO 0,6Y 0,06 63
9a 001,41 0,~1 ~70~4S,00 I,4s u,l3 175
gg,oo1,16 o,lo 140146,00 o 67 0,06 a~
~01 00 ~.0~ o,la244 2s~,oO o,a~ 0 07 93
0~ oo4,~9 o,~s s42259,00 90,64 7,09 9728
103,00 9,75 0,361176 ~60,00 ~3 44 ~13 ~6~1
10~,00 s,ai o s~70~ ~61,00 18,7a 5,93 9S0~
110,00 0,63 0,0676 ~6~,00 1~,61 1,11 Is~4
Ill,Oo 0,64 0,0677 263,oo o,y9 o,0~ 119
I 1 3, 00 1, 27 0, 1 1 ~ s3 323, oo 4,5~ 0,40 547
II~ 00 ~ 93 o,~7~ 3~4,oO o,77 0,o6 8 7
~IS,00 4,~8 o,~ss~29 32s,00 8,S9 0,7~ 103~
1~6,00 1,26 0,11~52 3~6,00 ~,7~ '~l lu6
,00 o,70 0,06 8S3~7,~o 4,~o 0 ~7 507
ZZ,000,75 o,o7 90~7,00 o,ss o oa ~S
~6,002,09 0,~0 2S1338,o0 34 sS ~,07 ~I~C
1~7 00 ~ ~1 o,~l287 139,00 7,39 0,6S 991
121,00 3,74 0,~bS1 ~40,00 68,43 6,C~ a~s6
1~9,00 ~,~1 0,3z ~3s 34~,00 ~1,47 1,Ol lla4
~30,00 ~ ~6 o,~s 26~ 34~,oo ~,9~ ~,98 4092
1)7,00 0,61 o,os 74 3~,oo S,Z3 0,4~ 6~
- 12 -
The remaining bromine-containing benzyltoluene
derivatives according to the invention can be obtained in
an analogous manner to the above described reaction scheme
by using conventional methods or also by direct bromination
S or bromination and chlorination of benzyltoluene, in which
case of course reaction mixtures are obtained which in
suitable ways, for example by gas chromatography, must be
separated into the bromine-containing benzyltoluene
derivatives of the general formula given above according
to the invention.
The non-flammable, biologically degradable functional
fluids of the invention may contain in addition to the
bromine-containing benzyltoluene derivatiaves additional
components and additives normally used in functional
fluids, for example corrosion inhibitors such as alkaline
earth sulfonates, stabilizers such as amine derivatives or
phenolic products, wear reducing additives such as zinc
dialkyldithiphosphate, acid acceptors such as epoxide
compounds, tin tetraphenyl etc., as well as anti-
foaming agents such as soap, silicone, glycol, phosphate
esters, and viscosity index enhancers such as polymeth-
acrylate, polyisobutylene. Further the bromine-containing
benzyltoluene derivatives used according to the invention
can be modified with various suitable products such as
mineral oil, glycols, etc.
The following examples serve to further clarify the
non-flammable biologically degradable functional fluids of
the invention.
Example 1
Investigation of the properties of the dibromobenzyl-
toluenes which are preferred as the bromine-containing
benzyltoluene derivatives of the invention.
a) Biological Degradability
The investigation of the biological degradability was
carried out by means of a known measuring procedure for
~c~
- 13 -
the determination of the biological degradability anionic
and non-ionic synthetic tensides (surface-active
substances) namely the OECD-screening test (Federal Law
Publication l (1977), page 245) (modified) for non-ionic
tensides.
Aerobic polyvalent microorganisms from the outlet of a
biological sewage plant were used as an innoculating
suspension. In this method the first sample was taken
after seven days, the second sample after 14 days and the
third sample after l9 days. The samples thus taken were
treated according to the directions of the tests indicated
above and the decomposition rate was determined by gas
chromatography.
The following results were obtained in this way:
sample after 7 days : 49.3% degraded
sample after 14 days : 69.1% degraded
sample after l9 days : 82.9% degraded
Surprisingly the dibromobenzyltoluene, which is a
preferred compound of the invention was biologically
degraded by more than 80%.
b) Combustion Test
A combustion test was carried out according to "the
6th Luxemburg Report on the requirements and tests of non-
flammable fluids for hydraulic power transmission and
control."
By this means it was shown that dibromobenzyltoluene
has a better combustion behaviour than tetrachloro-
benzyltoluene or polychlorinated biphenyl for example.
c) Investigation of corrosiveness
The corrosiveness of dibromobenzyltoluene was
investigated according to the methods of the 6th Luxemburg
Report mentioned above.
This involved immersing the metals steel, copper,
brass, aluminum, cadmium and zinc as well as the metal
pairs copper-zinc, steel-aluminum, steel-cadmium and
-
~ ~7
- 14 -
aluminum-zinc to two-thirds of their length in the fluid
to be examined (dibromobenzyltoluene) and were left
therein for 28 days at a temperature of 35C.
This experiment showed that in the case of all of the
test pieces the differences in weight resulting from
corrosion was less than l mg (the permissible difference
in weight was 20 mg)~
d) Compatability with Sealing Elements
For the investigation of the compatability with
sealing elements, a sealing element made from sealing
material 83 FKM 575 (Viton) was submerged in the fluid
under investigation and was kept for 21 days at 60C,
80C, 100C, 120C and 150C. Then the variation in
volume of the sealing element and the variation of its
Shore hardness were determined.
This investigation showed that the preferred
bromine-containing benzyltoluene derivative of the
invention, namely dibromobenzyltoluene used as such and
also in prepared hydraulic fluids had a particularly good
performance, in that it produced a volume alteration in
the sealing of between less than l and 2~ and a variation
in the Shore hardness of -3 degrees. The permissible
volume change and variation in the Shore hardness in this
testing method is up to 20~ and from -lO degrees,
respectively. Comparative tests using polychLorinated
biphenyls and tetrachlorobenzyltoluenes showed values of
volume change of ~0~ at a testing temperature of 150C.
In the case of these known products, care must be taken
when using them as hydraulic fluids not to exceed
temperatures of 100C because then the sealing material is
attacked to too great an extent so that it can be damaged.
e) Investiqation of Pyrolysis
__ ~
Dibromobenzyltoluene was pyrolysed at temperatures
between 150 and 700C in order to see if highly toxic
decomposition products are produced. The operation of the
5~
-- 15 --
test was carried out according to EPA - method No. 613.
Upon analysis with GCMS no highly toxic dioxin or
dibenzofuran (tri - and tetrabromo) could be determined
within the detection limits (0.5 ppb).
f) Investigation of the Viscosity-Temperature Relationship
The hydraulic fluid according ~o the invention of
example 2 below showed the following viscosity-temperature
relationships:
- 20C 8320 cSt
10 0C 430 cSt
20C 83 cSt
50C 21. cSt
~100C 6.6 cSt
A hydraulic fluid consisting of tetrachlorobenzyl-
toluene had the following relationships:
- 20Csolid, not measurable
0C 9730 cSt
+ 20C 320 cSt
~ 50C 25 cSt
20+100C 4 cSt
The foLowin~ examples 2 to 8 provide further
description of the invention and are concerned with the
formulation of non-flammable hydraulic fluids (examples 2
to 6) and insulating fluids (examples 7 and 8).
ExamPle 2
Formulation of a non-flammable hydraulic fluid:
93% Dibromobenzyltoluene
6% Viscosity index enhancer (polymethacrylate)
0.5% Corrosion inhibitor (barium sulfonate)
0.5% Antiwear additive (zinc dialkyldithiophosphate)
Example 3
Formulation of a non-flammable hydraulic fluid:
75% Dibromobenzyltoluene
23% Isopropyl triphenylphosphate
1% Corrosion inhibitor (alkylsulfamidocarboxylic acid)
1~ Acid acceptor (epoxide resin)
~d~
-
- 16
Example 4
Formulation of a non-flammable hydraulic fluid:
88% Dibromobenzyltoluene
10% Butile stearate
1% Corrosion inhibitor (fatty acid alkanolamide)
0.5~ Oxidation Stabilizer (amine derivative)
0.5% Antiwear additive (zinc dialkyldithiophosphate)
Example 5
Formulation of a non-flammable hydraulic fluid:
65% Dibromobenzyltoluene
25% Monobrominated benzyltoluene
9% Viscosity index enhancer (polyisobutylene)
1% Corrosion inhibitor (stearin amine derivative)
Example 6
Formulation of a non-flammable hydraulic fluid:
50% Dibromobenzyltoluene
45% Monobrominated xylylxylol
4.5% Viscosity index enhancer (polyisobutylene)
0.5% Corrosion inhibitor (stearin amine derivative)
Example 7
Formulation of an insulating fluid for electrical
equipment:
99.5% Dibromobenzyltoluene
0.3% Corrosion inhibitor (stearin amine derivative)
0.2% Epoxy resin
Example 8
Formulation of an insulating fluid for electrical
equipment:
50% Dibromobenzyltoluene
49.5% Monobrominated benzyltoluene
0.3% Corrosion inhibitor (stearin amine derivative)
0.2% Epoxy resin
