CA1142551A - Process for treating a chlorinated biphenyl compound - Google Patents
Process for treating a chlorinated biphenyl compoundInfo
- Publication number
- CA1142551A CA1142551A CA000356744A CA356744A CA1142551A CA 1142551 A CA1142551 A CA 1142551A CA 000356744 A CA000356744 A CA 000356744A CA 356744 A CA356744 A CA 356744A CA 1142551 A CA1142551 A CA 1142551A
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- Prior art keywords
- sodium
- potassium
- oil
- weight
- alkali metal
- Prior art date
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Classifications
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- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
- A62D3/00—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances
- A62D3/30—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents
- A62D3/34—Dehalogenation using reactive chemical agents able to degrade
-
- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
- A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
- A62D2101/20—Organic substances
- A62D2101/22—Organic substances containing halogen
Abstract
ABSTRACT OF THE DISCLOSURE A process for degrading or destroying a chlorinated biphenyl compound, more particularly one or more polychlori-nated compounds, commonly known as PCBs, by heating said compound with an alkali metal or a mixture of alkali metals or an alkali metal amalgam. The process can be conveniently carried out in a liquid organic medium. The chlorinated biphenyl compound may optionally be admixed with one or more trichlorobenzenes and/or one or more tetrachlorobenzenes.
Description
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 ll~Z~Sl 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 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 ll~ZS51 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.
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 ll~Z~Sl 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 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.
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 ll~Z551 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
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 ll~Z~Sl 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 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 ll~ZS51 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.
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 ll~Z~Sl 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 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.
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 ll~Z551 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.
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-ll~ZS51 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.
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.
ll~Z~
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.
. . _ 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 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.
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.
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.
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 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.
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.
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.
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-ll~ZS51 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.
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.
ll~Z~
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.
. . _ 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 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.
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.
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.
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 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.
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.
Claims (60)
1. A process for treating a chlorinated biphenyl com-pound which comprises reacting a chlorinated biphenyl compound with an alkali metal or a mixture of alkali metals or an alkali metal amalgam.
2. The process as claimed in claim 1 wherein the chlorinated biphenyl compound is heated with an alkali metal or a mixture of alkali metals or an alkali metal amalgam.
3. The process as claimed in claim 2 wherein the heat-ing is carried out in the presence of a liquid organic medium.
4. The process as claimed in claim 3 wherein the reaction is carried out in the presence of a liquid hydrocar-bon medium as the liquid organic medium.
5. The process as claimed in claim 4 wherein the hydrocarbon medium is a mono-, di- or tri-cyclic hydrocarbon which may be substituted by one or more alkyl substituents.
6. The process as claimed in claim 5 wherein the hydrocarbon medium is benzene, toluene, xylene, naphthalene, methylnaphthalene, anthracene, methylanthracene, a cycloparaffin or an alkyl substituted cycloparaffin.
7. The process as claimed in claim 4 wherein the hydrocarbon medium is a straight or branched chain linear paraffin.
8. The process as claimed in claim 1, 2 or 3 where-in the reaction is carried out in a liquid organic medium which is an electrical insulating liquid.
9. The process as claimed in claim 1, 2 or 3 where-in the reaction is carried out in the presence of a liquid organic medium which is a mineral oil.
10. The process as claimed in claim 1, 2 or 3 where-in the reaction is carried out in the presence of a liquid organic medium which is a mineral insulating oil.
11. The process as claimed in claim 1, 2 or 3 where-in the reaction is carried out in the presence of a liquid organic medium which is a mineral oil in the form of a white oil.
12. The process as claimed in claim 1, 2 or 3 where-in the reaction is carried out in the presence of a liquid organic medium which is a mineral oil in the form of a naph-thenic oil.
13. The process as claimed in claim 1, 2 or 3 where-in the alkali metal used is potassium, sodium or lithium.
14. The process as claimed in claim 1, 2 or 3 where-in the alkali metal used is potassium.
15. The process as claimed in claim 1, 2 or 3 where-in the alkali metal used is sodium.
16. The process as claimed in claim 1, 2 or 3 where-in the chlorinated biphenyl compound is present in the form of an askarel.
17. The process as claimed in claim 1, 2 or 3 where-in the chlorinated biphenyl compound is present in the form of an askarel as used in an electrical capacitor.
18. The process as claimed in claim 1, 2 or 3 where-in the chlorinated biphenyl compound is present in the form of an askarel as used in an electrical transformer.
19. The process as claimed in claim 1, 2 or 3 where-in the chlorinated biphenyl compound is present in the form of one or more compounds selected from the group consisting of tri-, tetra-, penta- and hexa-chlorobiphenyl, optionally in the presence of a trichlorobenzene or a mixture of a tri-chlorobenzene and a tetrachlorobenzene.
20. The process as claimed in claim 1, 2 or 3 where-in the chlorinated biphenyl compound is present in the form of a mixture of chlorinated biphenyl compounds, said mixture being such that the biphenyl has been chlorinated to a con-tent within the range of from about 40% to about 60% by weight of chlorine.
21. The process as claimed in claim 2 or 3 wherein the reaction mixture is heated to a temperature within the range of from about 70°C to about 200°C.
22. The process as claimed in claim 2 or 3 wherein the reaction mixture is heated to a temperature within the range of from about 90°C to about 190°C.
23. The process as claimed in claim 2 or 3 wherein the reaction mixture is heated to a temperature within the range of from about 70°C to about 120°C in the presence of potassium as the alkali metal.
24. The process as claimed in claim 2 or 3 wherein the reaction mixture is heated to a temperature within the range of from about 130°C to about 160°C in the presence of sodium as the alkali metal.
25. A process for destroying or degrading a chlori-nated biphenyl compound present in an electrical insulating liquid medium which comprises heating said liquid medium with an alkali metal or a mixture of alkali metals or an alkali metal amalgam.
26. The process as claimed in claim 25 wherein the electrical insulating medium is a mineral insulating oil.
27. The process as claimed in claim 26 wherein the mineral insulating oil is a white oil.
28. The process as claimed in claim 26 wherein the mineral insulating oil is a naphthenic oil.
29. The process as claimed in claim 25 or 26 where-in the alkali metal is potassium.
30. The process as claimed in claim 25 or 26 where-in the alkali metal is sodium.
31. The process as claimed in claim 25 or 26 where-in the amalgam is sodium amalgam or potassium amalgam.
32. The process as claimed in claim 25 or 26 where-in the heating is carried out within a temperature range of from about 70°C to about 200°C.
33. The process as claimed in claim 25 or 26 where-in the heating is carried out within a temperature range of from about 90°C to about 190°C.
34. The process as claimed in claim 25 or 26 where-in the alkali metal is potassium and the heating is carried out within a temperature range of from about 70°C to about 120°C.
35. The process as claimed in claim 25 or 26 where-in the alkali metal is sodium and the heating is carried out within a temperature range of from about 130°C to about 160°C.
36. The process of claim 25 or 26 wherein the chlo-rinated biphenyl compound is present in the form of an askarel.
37. The process of claim 27 or 28 wherein the chlorinated biphenyl compound is present in the form of an askarel.
38. The process of claim 25 or 26 wherein there is used from about 2 to about 8 parts by weight of sodium or potassium for each 1 part by weight of chlorinated biphenyl compound.
39. The process of claim 25 or 26 wherein there is used from about 3 to about 6 parts by weight of sodium or potassium for each 1 part by weight of chlorinated biphenyl compound.
40. The process of claim 27 or 28 wherein there is used from about 2 to about 8 parts by weight of sodium or potassium for each 1 part by weight of chlorinated biphenyl compound.
41. The process of claim 27 or 28 wherein there is used from about 3 to about 6 parts by weight of sodium or potassium for each 1 part by weight of chlorinated biphenyl compound.
42. A process for destroying or degrading a chlorinated biphenyl compound in an electrical insulating oil which is a mineral oil, optionally having present therein a trichloro- or tetrachlorobenzene, which comprises heating said oil with sodium or potassium at a temperature within the range of from about 70°C to about 200°C.
43. The process as claimed in claim 42 wherein the mineral oil is a white oil or a naphthenic oil.
44. The process as claimed in claim 42 wherein there is used from about 2 to about 8 parts by weight of sodium or potassium for each 1 part by weight of chlorinated biphenyl compound.
45. The process as claimed in claim 42, 43 or 44 where-in the oil is heated with potassium at a temperature within the range of from about 70°C to about 120°C.
46. The process as claimed in claim 42, 43 or 44 wherein the oil is heated with sodium at a temperature with-in the range of from about 90°C to about 190°C.
47. A process for destroying or degrading a chlo-rinated biphenyl compound present in an electrical insulat-ing liquid organic medium which comprises heating said liquid organic medium with an alkali metal selected from the group consisting of sodium, potassium and lithium.
48. The process as in claim 47 wherein the heating is carried out within a temperature range of from about 70°
to about 200°C.
to about 200°C.
49. The process as in claim 48 wherein the alkali metal is potassium and the heating is carried out within a temperature range of from about 70°C to about 120°C.
50. The process as in claim 47 wherein the alkali metal is sodium and the heating is carried out within a temperature range of from about 130°C to about 160°C.
51. The process as in claim 47 or 48, wherein there is used from about 2 to about 8 parts by weight of sodium or potassium for each 1 part by weight of chlorinated bi-phenyl compound present in the medium.
52. The process as in claim 49 or 50 wherein there is used from about 2 to about 8 parts by weight of sodium or potassium for each 1 part by weight of chlorinated biphenyl present in the medium.
53. The process as in claim 47 or 48 wherein the sodium or potassium is used in the form of pellets, balls, rods or lumps.
54. The process as in claim 49 or 50 wherein the sodium or potassium is used in the form of pellets, balls, rods or lumps.
55. The process as in claim 47 or 48, wherein there is used from about 2 to about 8 parts by weight of sodium or potassium for each 1 part by weight of chlorinated bi-phenyl compound present in the medium, said sodium or potas-sium being in the form of pellets, balls, rods or lumps.
56. The process as in claim 49 or 50 wherein there is used from about 2 to about 8 parts by weight of sodium or potassium for each 1 part by weight of chlorinated bi-phenyl compound present in the medium, said sodium or potas-sium being in the form of pellets, balls, rods or lumps.
57. A process for destroying or degrading a chlor-inated biphenyl compound present in an electrical insulating oil which comprises heating said oil with sodium or potassium at a temperature within the range of from about 70°C to about 200°C.
58. The process as in claim 57 wherein there is used from about 2 parts to about 8 parts by weight of sodium or potassium for each 1 part by weight of chlorinated bi-phenyl compound.
59. The process as in claim 57 or 58 wherein the oil is heated with potassium at a temperature within the range of from about 70°C to about 120°C.
60. The process as in claim 57 or 58 wherein the oil is heated with sodium at a temperature within the range of from about 90°C to about 190°C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000356744A CA1142551A (en) | 1980-07-22 | 1980-07-22 | Process for treating a chlorinated biphenyl compound |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000356744A CA1142551A (en) | 1980-07-22 | 1980-07-22 | Process for treating a chlorinated biphenyl compound |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1142551A true CA1142551A (en) | 1983-03-08 |
Family
ID=4117485
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000356744A Expired CA1142551A (en) | 1980-07-22 | 1980-07-22 | Process for treating a chlorinated biphenyl compound |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1142551A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5318228A (en) * | 1992-12-15 | 1994-06-07 | Neos Technology Inc. | Sodium dispersion and organohalide reaction processes |
-
1980
- 1980-07-22 CA CA000356744A patent/CA1142551A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5318228A (en) * | 1992-12-15 | 1994-06-07 | Neos Technology Inc. | Sodium dispersion and organohalide reaction processes |
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