Note: Descriptions are shown in the official language in which they were submitted.
5~1
"PROCESS FOR TREATING A CHLORIN~TED BIPHENYL COMPOUND"
This invention relates to a process for treating a
chlorinated biphenyl compound, more particularly a poly-
chlorinated biphenyl compound and especially mixtures of two
or more polychlorinated biphenyl compounds, commonly known and
referred to as PCBs. There may optionally be present, in addition,
a mixture of trichlorobenzenes and/or tetrachlorobenzenes.
It is known that biphenyl can be chlorinated to give
products which have outstanding chemical and thermal stabilities.
Individual chlorinated biphenyl compounds range from liquids to
high-melting crystalline solids. Mixtures of chlorinated
biphenyl compounds have achieved commercial significance because
they are useful in a variety of applications, such as in elec-
trical insulation, fire resistant heat-transfer and hydraulic
fluids, lubricants for use at high temperatures and pressures,
sealant and expansion media, and as constituents in elastomers,
cosmetics, adhesives, paints, lacquers, varnishes, pigments and
waxes.
In recent years, there has been some concern about the
toxic properties of chlorinated biphenyl compounds and attempts
have been made to devise suitable processes to degrade or des-
troy such compounds in order to convert them to less toxic or
non-toxic breakdown products. One such process believed to
be under consideration is a high temperature incineration
process.
~ Je have now found, and herein lies our invention, that
chlorinated biphenyl compounds and mixtures thereof, can be
destroyed or degraded by treatment at a ralatively low temp-
erature compared with the alternative high temperature incin-
eration process.
According to the invention as claimed herein there isprovided a process for treating a chlorinated biphenyl com-
~.~
5~1
pound which comprises treatinq a chlorinated biphenyl com-
pound with an alkali metal or a mixture of alkali metals
or an alkali metal amalagam. r~Ore particularly, our inven-
tion as claimed herein provides a process for treating a
chlorinated bi~henyl compound which comprises heating said
chlorinated biphenyl compound with an alkali metal or a
mixture of al~ali metals or an alkali metal amalgam.
Chlorinated biphenyl compounds may contain from one
to ten chlorine atoms and there are theoretically over two
hundred different chlorinated biphenyl compounds which might
exist. The empirical formulae for such compounds, their
molecular weights and percentage content of chlorine (based
on Cl=3~.45) are given below:
Empirical formula ~1O1ecular weight Percentage chlorine
C12HgC1 188.65 18.79
Cl2H8cl2 223.10 31.77
12 7 13 257.54 41.30
12 6 14 291.99 48.56
C12H5C15 326.43
20C12H4C16 360.88 58.93
C12H3C17 395.32 62.77
12 2C18 429.77 65.98
12HCl9 464.21 68.73
C12Cllo 498.66 71.18
Some of the chlorinated biphenyl compounds with which
this invention is concerned have been sold in the ~orm of
products which are mixtures o~ chlorinated ~iphenyl co~pounds.
Some of these products were available under a variety of
trade marks such as *Aroclor, *Chlorextol, *Dykanol, *Iner-
teen, *Noflamol, *Pyranol, *Therminol, *Clophen, *Fenclor,*Kannechlor, *Pyralene and *Sovol. Products containing
chlorinated biphenyl compounds ha~e ~een used ~or different
* ~rade Marks
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purposes and in different applications depending upon the
composition and the properties of each product. As examples
of such products there may be mentioned *Aroclor 1242, *Aro-
clor 1248, *Aroclor 1254 and *Aroclor 1260. The composition
of these products is given below to show how the percentage
of chlorine increases from Aroclor 1242 through Aroclor 1260.
It is understood that the last two digits in these Aroclor
products indicate the approximate chlorine content for each
product so that Aroclor 1242 and Aroclor 1260 contain approx-
imately 42% and 60% of chlorine, respectively, dependingupon the major chlorinated biphenyl compounds present in each
product.
Composition of Aroclor Products
Chlorinated Percentage of Compound present in
biPhenvl compound Aroclor Product
_ _ .
1 _ 1248 1254 1260
12 9 3
C12H8C12 13 2
C12H7C13 28 18
C12H6C14 30 40 11
C12H5C15 22 36 49 12
C12H4C16 4 4 34 28
C12H3C17 6 41
C12H2C18 8
C12HC19
Chlorinated aromatic hydrocarbons, and particularly
chlorinated biphenyl compounds, are used as electrical insu-
lating liquids for example for the impregnating and filling of
capacitors and as insulating and cooling media in liquid-
filled transformers. These liquids are usually mixtures ofchlorinated biphenyl compounds which are known in the art as
askarels. The askarels are non-flammable insulating liquids
which evolve essentially non-flammable gases when decomposed
by an electric arc.
* Trade Marks
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The word as~arel is used as a generic term for a
group of non-flammable synthetic chlorinated hydrocarbons used
as electrical insulating media, particularly for capacitors
and transformers. The askarels used for capacitors and trans-
formers are defined by the ~merican Society for Testing and
Materials (ASTM) in the ASTM D2233-74 and D2283-75 respec-
tively, as shown in the 1978 Annual Book of ASTM Standards
(Part 40 - Electrical Insulation). Askarels of varying com-
position are used. For example, for capacitor askarels,
D2233-74 describes four types of askarels which are defined
as Type A (biphenyl that has been chlorinated to a content
of 42% by weight), Type B (biphenyl that has been chlorinated
to a chlorine content of 54% by weight), Type C [a mixture
of 75% of type B and 25% of trichlorobenzene (mixed isomers)]
and Type D (same as type A except that higher boiling com-
pounds have been removed to a maximum level of 0.4%). In a
similar manner, for transformer askarels, D2283-75 describes
six types of askarels containing varying proportions of tri-,
penta- or hexa-chlorobiphenyl, some of these transformer
askarels also including trichlorobenzenes (mixed isomers) or
tri-tetra blend (mixed isomers of tri- and tetra-chloroben-
zenes.
When carrying out the process of this invention in
order to destroy or degrade one or more chlorinated biphenyl
compounds, it is convenient and desirable to conduct the re-
action in the presence of a liquid organic medium in order
to facilitate thorough admixture of the reactants and there-
by help to improve the rate of reaction.
The liquid organic medium, if used in the process,
may be any convenient liquid organic medium known to the
art to be suitable for use in the presence of an alkali me-
tal or an al~ali metal amalgam. The said liquid may be,
for example, a liquid hydrocarbon medium.
It is to be understood that the liquid medium may be liquid at
ambient temperature or it may be liquid at the reaction temper-
ature used to carry out the process of the invention. Suitable
liquid hydrocarbon media are those such as straight or branched
chain linear paraffins, for example C12, C14 or C16 paraffins
and mixtures thereof, and mono-, di- and tri-cyclic hydrocarbons,
which may be saturated or unsaturated and which may or may not
bear alkyl substituents, for example cycloparaffins, alkyl sub-
stituted cycloparaffins, benzene, toluene, xylenes, naphthalene,
methylnaphthalenes, anthracene and methylanthracenes. The
appropriate liquid medium for the reaction should be chosen
according to the range of temperature likely to be used in
the process.
In carrying out the process of the invention, a part-
icularly valuable embodiment is the use of a liquid organic
medium which is ~ electrical insulating liquid such as is
used in electrical equipment for example in capacitors, trans-
formers, cables and circuit breakers. Widely used insulating
liquids are hydrocarbon oils which are mineral oils obtained
as fractions of crude petroleum. A method used for the
determination of the carbon-type composition of mineral insulating
oils used in electrical equipment is given in ASTM D2140-66
(reapproved 1976). A mineral oil is defined therein by its
carbon-type composition expressed as a percentage of a) aromatic
ring-type carbon structures, b) naphthenic ring-type carbon
structures and c) paraffin chain-type carbon structures.
Examples of hydrocarbon oils used as electrical insulating
liquids are white oils, paraffinic oils and naphthenic oils.
White oils are essentially mixtures of saturated hydrocarbons
such mixtures containing a major proportion(about 60%) of paraffins
(aliphatic linear paraffins) and a minor proportion (about 40%) of
naphthenes (cycloparaffins) which are practically free from aro-
matic compounds. Naphthenic and paraffinic insulating oils are
essentially a mixture of saturated cyclic hydrocarbons (cyclo-
paraffins) and saturated linear hydrocarbons (paraffins) whichmay be substituted by alkyl substituents. A typical example of
a naphthenic oil is *Voltesso 35 transformer oil which is a
naphthenic transformer oil containing about 80~ of saturated
hydrocarbons (about half as linear paraffins and about half as
naphthenic cycloparaffins) with about 20% of aromatic compounds.
Transformer oils are such that they generally have a distillation
range from about 150C to about 250C.
The metal used in the process of the present invention
may be, for example, potassium, sodium or lithium and, of these,
preferred metals are potassium and sodium because of their re-
latively low melting points of 62C and 97.5C, respectively.
It is to be understood that the metal, such as potassium
or sodium, can be used in any form, for example as pellets, balls,
rods or lumps of potassium or sodium, or as sodium sand or pot-
assium sand. When used in these forms, it should be appreciated
by one skilled in the art that the reaction mixture is to be
stirred and heated so that the metal, such as potassium or sod-
ium, eventually melts in the liquid organic medium and thereby
becomes dispersed in a divided form which can provide a relativ-
ely large surface area of metal for reaction with the chlorin-
ated biphenyl compound. Metallic lithium may be used in the
form of lithium powder but a relatively higher reaction temp-
erature is usually required because of the melting point of lith-
ium which is about 185C. A commercially available product known
as Matheson sodium-in-oil dispersion (Type A 104), contain-
ing 40% w/w of sodium dispersed in a mineral oil, has been found
to be a convenient form of sodium for use in the present process.
A mixture of alkali metals, such as a mixture of sodium and
11~2551
potassium, may be used in the process.
In place of the alkali metal, these may be used on alkali
metal amalgam, such as sodium amalgam (Na/Hg) or potassium
amalgam (K/Hg). Since the amalgams contain only a relatively
small proportion of alkali metal, it will be appreciated that
a relatively larger amount by amalgam, such as potassium amalgam,
should be used in the process in order to provide the desired
amount of alkali metal for use in the reaction.
The liquid organic medium may or may not be maintained
under an inert gas atmosphere, for example nitrogen.
In carrying out the process of the invention, it is
usually necessary to heat the reaction mixture to a temperature
which is above the melting point of the metal used in the
process. The reaction temperature used will be dependent
upon the metal used, the type of liquid organic medium pre-
sent, the particular chlorinated biphenyl compound present
or mixture of chlorinated compounds present, the extent of
chlorination in polychlorinated compounds and the concentration
of such compounds in the reaction mixture. It is generally
necessary to heat the reaction mixture initially to a temperature
of about 70C and more particularly within the range of about
70C to about 200C, and especially in the range of about 90C
to about 190C. In some instances, a temperature range of about
110C to about 150C may be convenient. As it will be appreciated
by one skilled in the art, the lower chlorinated biphenyl com-
pounds, for example those containing mainly one, two, three or
four chlorine substituents, may be destroyed or degraded at a
relatively lower temperature such as within the range of about
70C to about 130C. The higher chlorinated biphenyl compounds
containing mainly five, six or seven shlorinated substituents,
may be destroyed or degraded at a relatively higher temperature
such as within the range of about 120C to about 190C and
particularly at a temperature of about 135C to about 165C.
551
The time taken to.carry out the process of the inven-
tion will generally be dependent upon the liquid organic me-
dium present, the concentration of chlorinated biphenyl com-
pounds present therein and the extent of chlorination in said
compounds, the metal used and the temperature at which the
reaction mixture is heated. It will be appreciated that, as
in many chemical reactions, an increase in temperature
increases the rate of reaction and the more substituted poly-
chlorinated biphenyl compounds, for example those containing
four, five, six or seven chlorine atoms, may be destroyed or
degraded more efficiently by operating at a temperature of
about 130C to about 190C, for example at about 140C to about
175C, for a relatively shorter period of time whereas the
chlorinated biphenyl compounds containing one, two, three or
four chlorine atoms, may be degraded or destroyed at about
70C to about 115C for a similar relatively shorter period
of time. The process may thus be completed in about half an
hour or it may take several hours, for example from about 2 to
about 15 hours, more particularly from about 3 hours to about
6 hours, depending upon all the factors mentioned above to be
taken into consideration and their effect upon the rate of
reaction.
When using potassium metal in the process of this in-
vention, a convenient temperature may be within the range of
about 70C to about 120C and the time taken for the reaction
may be of the order of about 1.5 to ahout 2.5 hours. On the
other hand, when using sodium metal, the temperature may con-
veniently be within the range of about 130C to about 160C
and the reaction time may be of the order of about 2 hours to
about 6 hours.
The amount of metal used in the process may be varied
according to the concentration of the chlorinated biphenyl
compounds and the degree of chlorination of such compounds, the
temperature at which the process is carried out and all other
114~SSl
faetors affecting the reaetion.
As an example, it has been found that the amount of
metal to be used may be such that the cGncentration of the
metal may be in a ratio of from two to about eight times the
concentration of the chlorinated biphenyl compounds in the
liquid organic medium. Thus for a liquid medium containing
about 1.0 part by weight of chlorinated biphenyl compounds,
it may be convenient to use from about 2 to about 8 parts by
weight of metal, and particularly from about 3 to about 6 parts
by weight of metal, such as potassium or sodium. The amount
of metal used will depend upon the factors mentioned above which
affect the reaction, the cost of the metal used and the ef-
ficiency of the process. It has generally been found that as
the eoncentration of chlorinated biphenyl compounds in the
liquid organic medium decreases, it may become necessary to
use a greater ratio of metal. In these circumstanees, it is
sometimes appropriate to use a large excess of metal in order
to increase the rate of reaetion and thereby destroy or de-
grade the chlorinated biphenyl compounds which may be present
in a relatively low concentration in the liq~lid organic medium.
It has been found that when using an electrical in-
sulating oil as the liquid organic medium, such as a mineral oil,
for example a naphthenic oil or a white oil, containing
chlorinated biphenyl compounds, treatment by heating with an
alkali metal, especially potassium or sodium,destroys or degrades
the ehlorinated compounds and when the reaction mixture is allowed
to settle, a dark sludge is deposited. This sludge may contain
metal chloride, any excess of metal and various other by-products.
When the reaction mixture is filtered or is subject~d to cen-
trifugation and the sludge is thereby removed, the residual oilis of sueh a quality that it may he reused for various purposes
as an oil which is free, or virtually free, from chlorinated bi-
phenyl and/or chlorinated benzene eompounds.
~1~25Sl
It is thus a preferred feature of the invention to
treat a mineral oil, such as white oil, or a naphthenic oil,
or a hydrocarbon oil, such as a paraffinic oil or a cyclo-
paraffinic oil, any of which oils may be an electrical insul-
ating oil, said oil or oils containing a proportion of one or
more chlorinated biphenyl compounds, and optionally one or
more chlorinated benzene compounds, by heating with an alkali
metal or a mixture of alkali metals or an alkali metal amalgam,
and thereafter, if desired, recovering the treated oil from
the reaction mixture.
The preferred electrical insulating oil is a mineral oil
such as white oil, paraffinic oil or naphthenic oil which may or
may not conform to the carbon-type composition as defined in ASTM
D2140-66 (reapproved 1976). The preferred alkali metal to be
used is potassium or sodium. By use of this process on service-
aged electrical insulating oil, for example transformer oil
which has been in service in a transformer for some years, con-
taining one or more chlorinated biphenyl compounds in the form
of an askarel, it is possible to destroy or degrade the said
compounds. The oil recovered from this treatment process is
generally found to contain less than about 10 parts per million
(ppm) by weight of chlorinated biphenyl compounds and, in some
instances, the oil recovered is found to contain less than 1 ppm
by weight of chlorinated biphenyl compounds.
The process of this invention is illustrated by, but
not limited to, the following examples:
11~2SSl
E ~PLE 1
Reaction of approximately 1% by weight askarel 1242 in Voltesso
35 transformer oil with metallic potassium
= _
The askarel 1242 used was a chlorinated aromatic hydro-
carbon (askarel) liquid having a composition conforming to ASTM
Specification D2233-74. This askarel conformed to "Type A"
askarel liquid, consisting of biphenyl chlorinated to a chlo-
rine content of 42 weight percent. Chromatographic analysis
(analysis by high-pressure liquid chromatography, and electron-
capture gas chromatography) showed that this liquid consisted
of a range of polychlorinated biphenyls, corresponding to the
components in Aroclor 1242.
The Voltesso 35 transformer oil used was a naphthenic
transformer oil containing approximately 80% saturated hydro-
carbons and 20~ aromatic hydrocarbons, as obtained from Esso
Imperial Oil Co. Ltd., Canada.
A solution of 3.6 g of askarel 1242 in 357 g of Vol-
tesso 35 transformer oil was made up by weighing and mixing
of the two liquids. A portion of this solution (90 g) was
transferred to a 250 mL Ehrlenmeyer flask for reaction with
metallic potassium. Pieces of potassium metal were cut from
lump metal (BDH Chemicals Ltd. Product No. 29580), and the
pieces, weighing a total of 5.3 g, were transferred as quickly
as possible to the flask. A *Teflon-coated magnetic spinbar was
placed in the flask, which was then sealed with a stopper through
which had been fitted a mercury-in-glass thermometer and a
narrow tube leading to an oil trap. The flask, and its c~ntents,
were then placed on a laboratory hot-plate/magnetic stirrer and
the flask was then secured by means of a stand and clamp.
Reaction took place under the application of heat and
stirring. The independent heat and stirrin~ controls of the
hot-plate were adjusted to gradually raise the tempera-
*Trade Mark 11
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ture of the mixture to above the melting point of the potas-
sium (about 65C) while maintaining rapid stirring. It was
found that the potassium dispersed into fine particles soon
after it melted, which were quite easily kept in suspension
by stirring. A reaction was then observed to take place with
the formation of a finely divided black sludge.
In this experiment, the temperature of the mixture
was raised from room temperature to 73C in approximately 10
minutes, and the mixture was then maintained at temperatures
between 73C and approximately 102C for a further 90 minutes.
The mixture was stirred throughout the heating period. At the
end of this time a sample of the reacted mixture was taken for
analysis (gas chromatography using an electron-capture detector)
and was found to contain less than 10 ppm by weight askarel 1242.
On allowing the mixture to cool and settle in the reaction flask,
the oil clarified and was found to be almost water-white in
colour.
Infra-red analysis showed that the tranformer oil had
not changed in composition appreciably by treatment with the
potassium, except for the removal of the askarel 1242, and
the introduction of a small quantity of a material with an
infra-red absorption corresponding to biphenyl.
Analysis for askarel remaining in the reaction mix-
ture was performed by gas chromatography using an electron-
capture detector. The analysis conditions provided separa-
tion and measurement of the main components of the askarel
and resulted in a minimum detectable limit of less than 2ppm
by weight askarel in the reaction mixture.
Infrared analysis was performed by recording the ab-
sorbance of the liquid sample between 4000 wavenumbers(cm 1) and 200 wavenumbers (cm 1) using a fixed path-length
NaCl window cell (0.2 mm).
11~2'jSl
EXAMPLE 2
Reaction of 1% by weight transformer askarel in Voltesso 35
transformer oil with metallic potassium
The transformer askarel used was a chlorinated aroma-
tic hydrocarbon (askarel) liquid having a composition confor-
ming to ASTM Specification D22~3-75. This askarel conformed
to "Type B" askarel liquid, consisting of biphenyl chlorinated
to a chlorine content of 60 weight percent, diluted with a
mixture of isomers of trichlorobenzene and tetrachlorobenzene
(tri-tetra blend) in the ratio 45 parts of chlorinated biphenyl
to 55 parts of tri-tetra blend weight percent. Analysis by
high-pressure liquid chromatography and electron-capture gas
chromatography showed that the chlorinated biphenyl component
of this liquid consisted of a range of polychlorinated bi-
phenyls, corresponding to the components in Aroclor 1260.
The Voltesso 35 transformer oil was the same as that
used in Example 1.
90 g of a solution of 1% by weight transformer aska-
rel in Voltesso 35 transformer oil was treated with 7.5 g of
potassium metal (cut from larger pieces of lump potassium
metal) under experimental conditions similar to those used
in Example 1 except that, after heating from room temperature
to 90C in approximately 15 minutes, the reaction temperature
ranged from 90C to 115C over a period of approximately 90
minutes. The mixture before reaction was a clear, slightly
yellow liquid and darkening of the mixture was observed to
commence at temperatures above the melting point of the pot-
assium (approximately 65C). The concentration of transfor-
mer askarel in the mixture after reaction was measured, and
was found to be less than 10 ppm by weight. On allowing the
mixture to cool and settle, the oil became clear and almost
water-white in colour. Infra-red analysis showed that the
;255~
oil had not changed in composition appreciably by treatment,
except for the removal of the transformer askarel and the in-
troduction of a small quantity of a material with an infra-
red absorption corresponding to biphenyl.
EX~lPLE 3
Reaction of 1% by weight tranformer askarel in Voltesso 35
transformer oil w th metallic sodium
90 g of a solution of 1% by weight transformer aska-
rel (Type B as in Example 2) in Voltesso 35 transformer oil
was treated with 4.0 g of sodium metal cut from larger pieces
of lump sodium metal (BDH Chemicals Ltd. Product No. 30101).
The mixture was stirred and heated under experimental condi-
tions similar to those used in Example 1 except that, after
heating from room temperature to 130C in approximately 30
minutes, the reaction temperature ranged from 130C to 165C
over a period of approximately 3 hours. The mixture before
reaction was a clear, slightly yellow liquid and darkening
of the mixture was observed to commence at temperatures above
the melting point of the sodium (approximately 97C). The
concentration of transformer askarel in the mixture after
reaction was measured, and was found to be less than 10 ppm
by weight~ On allowing the mixture to cool and settle, the
oil became clear and was slightly brown in colour. Infra-
red analysis showed that the oil had not changed in composi-
tion appreciably by treatment, except for the removal of the
transformer askarel and the introduction of a small quantity
of a material with an infra-red absorption corresponding to
biphenyl.
EXAMPLE 4
Reaction of 1% by weight askarel 1242 in Voltesso 35 trans-
-
former oil with metallic sodium
90 g of a solution of 1% by weight askarel 1242 in
14
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Voltesso 35 transformer oil was treated with 4.0 g of metal-
lic sodium (cut from larger pieces of lump sodium metal) under
experimental conditions similar to those used in Example 1
except that, after heating from room temperature to 130C in
approximately 40 minutes, the reaction temperature ranged from
130C to 150C over a period of approximately 5 hours. The
mixture before reaction was a clear, slightly yellow liquid
and darkening of the mixture was observed to commence at tem-
peratures above the melting point of the sodium (approximate-
ly 97C). The concentration of askarel 1242 in the mixture
after reaction was measured, and was found to be less than 10
ppm by weight. On allowing the mixture to cool and settle,
the oil became clear and yellow in colour. Infra-red analy-
sis showed that the oil had not changed in composition appre-
ciably by treatment, except for the removal of the askarel
1242 and the introduction of a small quantity of a material
with an infra-red absorption corresponding to biphenyl.
E ~ lPLE 5
Reaction of 1% by weight askarel 1242 in Voltesso 35 trans-
former oil with metallic lithium
90 g of a solution of 1% by weight askarel 1242 in
Voltesso 35 transformer oil was treated with 0.9 g of metal-
lic lithium taken from a larger quantity of 140 mesh lith-
ium metal powder (Alfa Products, Danvers, Mass., U.S.A.). The
mixture was stirred and heated under experimental conditions
similar to those used in Example 1 except that, after heating
from room temperature to 130C in 30 minutes and then gradually
raising the temperature to 180C over a further period of
3.5 hours, the reaction temperature ranged from 180C to 190C
over a period of approximately 3 hours. Darkening of the
mixture was observed to commence at temperatures above the
melting point of the lithium (approximately 185C). The
2~1
concentration of askarel 1242 in the mixture after reaction
was measured, and was found to be less than 50 ppm by weight.
On allowing the mixture to cool and settle, the oil became
clear and brown in colour. Infra-red analysis showed that
the oil had not changed in composition appreciably by treat-
ment, except for the removal of the askarel 1242 and the
introduction of a small quantity of a material with an infra-
red absorption corresponding to biphenyl.
EXAMPLE 6
Reaction of 1% by weight tranformer askarel in Voltesso 35
. .
transformer oil with metallic lithium
.
70 g of a solution of 1% by weight tranformer aska-
rel (Type B as in Example 2) in Voltesso 35 transformer oil
was treated with 0.95 g of metallic lithium (taken from a
larger quantity of 140 mesh lithium metal powder) under
experimental conditions similar to those used in Example 1
except that, after heating from room temperature to 185C in
100 minutes, the reaction temperature ranged from 180C to
190C over a period of approximately 4.5 hours. Darkening
of the mixture was observed to commence at temperatures
above the melting point of the lithium (approximately 185C).
The concentration of transformer askarel in the mixture after
reaction was measured, and was found to be less than 10 ppm
by weight. On allowing the mixture to cool and settle, the
oil became clear and brown in colour. Infra-red analysis
showed that the oil had not changed in composition appreciably
by treatment, except for the removal of the transformer askarel
and the introduction of a small quantity of a material with
an infra-red absorption corresponding to biphenyl.
EX~IPLE 7
Reaction of 1% by weight transformer askarel in xylenes with
metallic potassium
100 g of a solution of 1~ by weight transformer aska-
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rel (Type B as in Example 2) in xylenes (mixture of o-, m-
and p-isomers) was treated with 7.0 g of metallic potassium
(cut from larger pieces of lump potassium metal) under
experimental conditions similar to those used in Example 1
except that, after heating from room temperature to 140C in
approximately 60 minutes, the reaction temperature was maintained
at the boiling point of the mixture (approximately 140C) over a
period of approximately 4 hours. The mixture before reaction
was a clear, almost colourless liquid. Darkening of the mixture
was observed to commence at temperatures above the melting point
of the potassium (approximately 65C). The concentration of
transformer askarel in the mixture after reaction was measured,
and was found to be less than 10 ppm by weight. On allowing the
mixture to cool and settle, the liquid became clear and water-
white in colour.
EXAMPLE 8
Reaction of 1~ by weight askarel 1242 in xylenes with metallic
sodium
100 g of a solution of 1% by weight askarel 1242 in
xylenes (mixture of o-, m- and p-isomers) was treated with 5.35
g of metallic sodium (cut from larger pieces of lump sodium
metal) under experimental conditions similar to those used in
Example 1 except that, a flask equipped with a water-cooled
condenser was used to provide reflux conditions. After heating
from room temperature to 140C in approximately 60 minutes, the
reæticn temperature was maintained at the boiling point of the
mixture over a period of approximately 4 hours. The mixture be-
fore reaction was a clear, almost colourless liquid and darkening
of the mixture was observed to commence at temperatures above
the melting point of the sodium (approximately 97C). The concen-
tration of askarel 1242 in the mixture after reaction was measur-
ed, and was found to be less than 10 ppm by weight. On allowing
the mixture to cool and settle, the liquid became clear and water-
white in colour.
17
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EX~lPLE 9
Reaction of 1.2% by weight tranformer askarel in white oil
with metallic sodium
.
The white oil used was an oil containing approximately
99% saturated hydrocarbons with small quantitites of aromatic
hydrocarbons, the oil being obtained as "60 Neutral HT" from
Gulf Canada Ltd.
The metallic sodium used was a commercial product in
the form of a sodium-in-oil suspension containing 40% hy
weight of metallic sodium in mineral oil. The suspension
was obtained from Matheson Gas Prodcuts, 61 Grove St., Glou-
cester, ~Iass., U.S.A. 01930 Cat. No. A 104.
100 g of a solution of 1.2% by weight transformer
askarel (Type B as in Example 2) in white oil was treated
with 10 g of the metallic sodium in oil suspension described
above under experimental conditions similar to those used
in Example 1 except that, after heating from room temperature
to 100C in approximately 30 minutes, the reaction was main-
tained 100C for 23 hours, then to approximately 130C for
21 hours and finally at approximately 155C over a period of
approximately 6 hours. The concentration of transformer
askarel in the mixture after reaction was measured, and was
found to be less than 10ppm by weight. On allowing the
mixture to cool and settle, the liquid became clear and
almost colourless.
EXAMPLE 10
. . _
Reaction of approximately 90 ppm by weight mixed askarels in
service-aged transformer oil with metallic potassium
308 g of a service-aged transformer oil containing
approximately 90 ppm by weight of mixed askarels was treated
with 2.95 g of metallic potassium (cut from larger pieces of
18
ll~ZSSl
lump potassium metal) under experimental conditions similar
to those used in Example 1 except that, after heating from
room temperature to 140C in 30 minutes, the reaction temp-
erature ranged from 140C to 145C over a period of approxi-
mately 3,5 hours. The mixture before reaction contained
solid and liquid contaminants from service ageing. The concen-
tration of askarels in the mixture after reaction was mea-
sured and was found to be less than 10 ppm by weight. After
cooling and filtering the mixture, the oil was clear and
brown in colour, and measurements of the interfacial tension
and neutralization number of the oil were found to be equiv-
alent to those of new transformer oil.
The interfacial tension of the oil against water was
measured according to ASTM Test Method D971-50. This test
is often applied to mineral oil to give a reliable indication
of the presence of hydrophilic compounds. The minimum value
of the interfacial tension of new mineral insulating oil for
use in transformers and switchgear is 40 dynes/cm, according
to ASTM Specification D1040-73.
The neutralization number of the oil was measured
according to ASTM Test Method D664-58. The neutralization
number is expressed in mg of potassium hydroxide required to
neutralize acidic constituents present in 1 g of sample.
The maximum neutralization number of new mineral insulating oil
for use in transformers and switchgear is 0.05 mg KOH/g oil,
according to ASTM Specification D1040-73.
EXAMPLE 11
Reaction of 2% by weight askarel 1242 in mineral oil (heavy)
with metallic potassium
The mineral oil theavy) used was a ~leavy USP Medici-
nal grade mineral oil conforming to DIN 179051, obtained from
Stanley Drug Products Ltd., North Vancouver, B.C., Canada.
19
551
100 g of a solution of 2~ by weight askarel 1242 in
mineral oil ~heavy) was treated with 8.9 g of metallic potas-
sium (cut from larger pieces of lump potassium metal) under
experimental conditons similar to those used in Example 1
except that, after heating from room temperature to 92C in
approximately 20 minutes, the reaction temperature ranged from
92C to 112C over a period of approximately 1.5 hours. The
oil before reaction was a clear, colourless liquid. The
concentration of askarel 1242 in the mixture after reaction
was measured and was found to ke less than 10 ppm by weight.
On allowing the mixture to settle, the oil became clear and
colourless.
EXAMPLE 12
Reaction of 2~ by weight transformer askarel in mineral oil
(heavy) with metallic potassium
100 g of a solution of 2~ by weight transformer aska-
real (Type B as in Example 2) in mineral oil (heavy) was
treated with 12.75 g of metallic potassium (cut from larger
pieces of lump potassium metal) under experimental conditions
similar to those used in Example 1 except that, after heating
from room temperature to 120C in approximagely 20 minutes,
the reaction temperature ranged from 120C to 125C over a
period of approximately 2 hours. The oil before reaction was
a clear, colourless liquid. The concentration of transformer
askarel in the mixture after reaction was measured, and was
found to be less than 10 ppm by weight. On allowing the
mixture to settle, the oil became clear and almost colourless.
ll~Z551
EXAMPLE 13
Reaction of 1% by weight askarel 1242 in Voltesso 35 transformer
_ _ _ _ _
oil with potassium amalgam
50 g of a solution of 1% by weight askarel 1242 in
Voltesso 35 was treated with 102.7 g of an amalgam containing
approximately 2% potassium in mercury under experimental
conditions similar to those used in Example 1 except that, after
heating from room temperature to 130C in approximately 2 hours,
the reaction temperature ranged from 130C to 135C over a
period of approximately 20 hours. The mixture before reaction
was a clear, almost colourless liquid. Darkening of the mix-
ture was observed to commence at temperatures above about 130C.
The concentration of askarel 1242 in the mixture after reaction
was measured, and was found to be less than 10 ppm by weight.
On allowing the mixture to cool and settle, the liquid became
clear and slightly brown in colour.
EXAMPLE 14
Reaction of 1% by weight of a mixture of_tri- and tetra-chlorin-
ated benzenes in mineral oll (heavy) with metallic potassium
100 g of a solution of 1% by weight of a blend of tri-
and tetra-chlorinated benzenes in heavy mineral oil was treated
with 5.0 g of metallic potassium under experimental conditions
similar to those in Example 1 except that, after heating from
room temperature to 110C in 30 minutes, the reaction tempera-
ture was maintained at approximately 110C over a further period
of approximately 1 hour. The mixture before reaction was a
clear, almost colourless liquid and darkening of the mixture
was observed to commence at temperatures above the melting
point of the potassium (approximately 65C). The concentration
of tri- and tetra-chlorobenzenes in the mixture after reaction
was measured and was found to be less than 10 ppm by weight.
On allowing the mixture to cool and settle, the liquid became
clear and water-white in colour.
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