Document 6wbOgke4GgbKnaXN3zVnx8O0R

19, 1960 raeenb ixiok ''Dayton Case 2073 j. dazzi elect*ical Devices ril*d Au| 4, IMS 2,945,994 FIG- I / DIELECTRIC METAL CONTAINING ELECTRODES BIS I TETR AHYOROFURFURYLOXY)CHLOROBENZEN FIG-4 15 17 FIG - 3 FIG - 5 METAL FOIL PAPER IMPREGNATED WITH 2* (DICHLOROPHENOXY) METHYL TETRAHYDRoFURAN INVENTOR. JOACHIM OAZZi BY - ATTQftNCr HONS 201752 United States Patent Office 2,945.994 Patented July 19, i960 12 moo to (be pnor art diclcciric materials such * the d&- terioraiioo oi paper miulmoo iad men I parti ii duam- J.94S.994 led or materially reduced Still mother object >i to provide electrical appxratu* having a long, useful lilt and ELECTRICAL DEVICES jwrhlio Dull. Dsyion, OhJo, assignor to Moataate Cdcitilexl Company, St. Louis, Mo, * corporation of Delaware Filed Aug. 4.19St, StT. No. 752,194 f good dielectric stability. According to the invention, these and other objects which wilt be hereinafter disclosed are provided by the following invention wherein (here is provided electrical spparstus comprising, in comhiDatJoo, conducting tit. 19 menu disposed in spaced relationship to each other and 4 Claim* '{CL 317--251) adapted dining operation of tbs apparatus, to have difference in electrical potential therebetween and, in terposed between said element* for insulating one from the other, a liquid dielactne medium comprising an ether Tit present invention relate* to electneal devices sod 14 of the formula M-e particularly deals with apparatus comprising a ^Tbinauon of clectneiiy conducting elements and di- 1 c.-nilVe i|niwsu'lia--tiing -media. The me of * dielectric is required in certain electneal 0 ; ,j .j.t mating of electrical contact in the absence of air I *f 0( explosive mixtures. The requirements for such ' iVutncs are. among other things, very high resistance ^ which R is selected from the class consisting of th* ' j the flow of electric currents, high stability to atmoa- furfuryl and the telrabydrefurfuryl radicals and X is ` :Xnc conditions si ordinary ind it somewhat elevated selected from the cists consisting of chlorine and the 1 mpctaiures, high resistsoce io thermal decomposition, radical --O--R. I a* vpor pressure, tow congealing temperature, low in* Compouada hiving the above formula are readily pm. J `.mmsbilily end high flash point. Preferably the 4i- pared by heittPg tnchtofoheazena with furfuryl or tetri* j rtrine should be a mobile liquid even at relatively low hydrofurfuryl alcohol in the presence of as alkali mcial j u'prraturei and should be a good beat transfer agent hydroxide, 1 eodiitm, potassium or lithium hydroxide / la commercial practice, high boding fractions of pa- One class of compounds of the above formula includes : altum (Stsulliic* have been largely used for this purpose. tbe 2-(dtchloropbenoiyinetby|)furan* or the 2-fdiebloro- l These liquid* do not satisfy >11 of the above-slated re- . phenoxymethyll-tetrsbydrofuraos, eg, 2-{2,3-dicbloro- ,..rtments. They are relatively poor heat transfer ag. ,, pbeooxymeihylIfursn. 2-OJ-dschloropheooxymethyO* . -a ad under the condition* of their use they gradually form, 2-|2.b-dkhlorophcnoiymtlbrl) furan. 2 - (3.4-di- itompose with tfte formation of underirahie produett chlorophenoxymethylUetrahydrofuran, 2 - (2.5-dichloro- , it :h sdvtrsely influence the electrical properties Some phenoxymetbyDtetrahydrofurio, 2 (3,5-dichloropben. , c' ilwse product* are tarry, and other* are appreciably oxymethyl)(urea, 2>{),4-dietiloit>pfaeooxytnetbyl>fiiran> 1 i.'.i'ie and may present fire and explosion hazards. ^ Anoibcr disadvantage of the miners! oils is that they Another presently useful claas of compounds having tha i -,l to form drpoane generally known as sludge" during ,bove formula and prepared by the condensation of a In- jc penod of their use. This it due to oxidation and de- chlorobenzene with furfuryl or letrahydrofurfurvl alcohol --position and alto results to some extent in the forme- include* the bis(furfuryk>iy)chlorobeDZeoet ind the his . .-a of acids wfoeh u equally undeniable. The sludging. a ftetrihydrofurfuryksxy)chlorobcnzenes, e.g, 2,3 - bit . 'dielectrics during use i* tenons disadvantage and re- (telrahydrofurfuryloxylehtocobenitne. 3,5 - bislfurfury- ,ntuber replsccmeot of ths oil or trtattnant to remove i U iiudge end revivify the dielectric. A satsfactory - loxy)chlcHt>benzct>e, 1J hitffurfuryloxy)cblorohname, J,4 . hh(tetrafaydrofiarfurykuy)chlorobszeDe, 2.J - bis ; Mr liquid should not sludge or undergo substantial Urtnhydrefurfuryloxy KhJOfobenxene, 2.4 bisffurfurb'ntnous change during use and It is one of the objects M yloxy Jchiocobenztna. 2.3-bii(fiufuryloay)cblorobciuene. i' 'hi invention to provide a liquid which does not poaiisa tc. is uadcairahle disadvantage characteristic of the mineral Formation of the present ethers Occurs by replacement I-- ` TbsundeabnUe affect of decomposition is further meal- wof monoev voir itw"vo vosf ithne wchulovfriunve iaivtonmus nof uthhe itcnwchiilwotgoubceQn-' *ene by one or two furfurytoxy radicals The replace- 1 ^ *b*n the mineral oils are used u capacitor 1m- ^ event reaction takae place readily by heating the in- rrpuois, Th* aedti Ugh operating temperatures ted chlorobenzene with furfuryl Or ittra-bydrofurfuryl ileo- I current vnflsgsi, capaciiors impregnated therewith hoi in ths presence at an alkali metal hydroxide Since r-'.vfB a characteristic type of deterioration which re- (ha reaction may result in the replacement of more than 1 w Increasing leakage current, a short capsci- one chlorine atom, when desiring s preponderance of ths ' ^*. visible localized decomposition of the dielectric ^ substitution of only one ehlonne atom by the furfurytoxy ul corrosion of the electrodes Moreover, in the case ' J tipitiun operating on alternating current, the de- or tetrihydrofurfuryloxy radical, it is generally advisable to use large excess of the tncblorobciuene On the ; "Mii ian sometimes results in in excessive increase is other hand, when the maior product to be obtained is , f*c!or : the dielectric matene). the diether, an excess of the furfuryl or tetrahydrofur* , ' ' it, iherrlare, an object of the present invention to ^ furyl alcohol is advsntsgeously used The quantity of ' " " >' t method for the insulation of elements in eleo- ippsratu* wherein the above objectionable proper* i irt other completely eliminated or substantially rstif.1 alkali metal hydroxide employed ti also somewbit controlling in the type of product obtained, Hydrogen chloride is Jiberated u tha replacement of the nuclear chlorine by the furfurytoxy or fetrehydrofurfuryloxy . T...se.i wi CJIC4#, blVIHj gwnwaac#, w^Wj IMktglg, VJuan and th* like wherein tha deleterious action com- VI IUS{ UK WIVWrViUM Vf UN WEIS IVVUjU be present in the reaction mixture enough of the alkali HONS 201753 9.04S.B04 3 to neulzaljz the liberated acid. Usually from one to ... 4 chiiffeaJ deterioration it reduced by impregnating the in two moles of the alkali metal hydroxide per mole of the sulation with oil, this was of little advantage as noted furfuryl aT tclrahydrofurfuryi alcohol it used An ex- above Accordingly, the an resorted to other impreg rets of sodium hydroxide is not detrimental to the re nating agents, particularly the highly chlorinated ara< tenon, whereat a molar quantity which n aubtiamialty a mauc hydrocarbons These materials have dielectric !a, than that of the alcohol tt conducive to lower yieJda Siren phi which are higher than those of the mineral oils of ether product, In addition, they are non-flammable and more stable to The rrocuon tune and temperature appearj to have the influence of air, moisture and light. However, then hide, tf any, effect on the nature of the ether product. general uuluy bat been somewhat hampered in that under Although a primarily formed mono-ether will react with 10 high operating lemperaiurei and voltages decomposition another mole of furfuryl or tetrahydrofurfuryi alcohol of said highly chlorinated hydrocarbons is manifested to yield a di-ttber, higher lemperaiurei or continued heal Hydrogen chloride is evolved; and this attacks not only ing do not uifliee in effecting substantial conversion to the paper which had been impregnated but alto tbe meta! the di-ether An excess of one of said alcohol* over portions of th* capacitor. that required tor replacement of one chlorine atom IS Th* presently provided ethers are high-boding ma should be present in order to obtain any tuhstaniial for terial# which possess high resmiviues and low power mation of the di-etber. Whether the reactant quantities factora Their tuhiiity to high temperature* it evi present are those which favor mono-substitution (excess denced by little or no change in power factor readings of inch) oro benzene) or whether the properties are Such after heating for 14 hours at 100* C Their stability as to favor di-iubsittuuoo (excess of one of said alco go is further illustrated by continued high rmistivitiei, which hols). ether formation occurs after heating at a tempera indicates freedom from conducting ions which would be ture of from IOO' C. to ISO* C, and preferably of from present if decomposition of th* ethers had occurred 125' C to 200* C for a lime of, say, several hours The present ethers remain liquid at low temperatures, to s day. The progress of the reaction can be generally whereby there is avoided a decrease to dielectric 600- fallowed by notiog tbe alkalinity or the quantity of water gC Slant due to freezing of (he dipoles. being formed While provision for removal of water Tbe above characteristics thus apeak for eminent suit during the reaction it not required, better yields of ether ability of theta ethers as impregnating agents for celiu- product and a ready means of determining reaction rat* lone material*, and an embodiment of tbe present toven- are afforded by operating m a reaction vessel which is don is the provision of unproved eellulosie insulating equipped with some wafer-removing facility, t *., a water SO agents comprising porous materials derived from cellu trap or take-off head. lose, eg., pulps, fibers, textiles or papers derived from Although, as above stated, reaction of the triehloro* wood, eotioo or Uoen, which porous product* have been benzene and the furfuryl or tetrahydrofurfuryi alcohol impregnated with said ethers. A noteworthy feature of can be so directed at to result in a preponderance of the present invention i* the provision of e capacitor com either mono- or diether formation, generally the product ae prising a pair of electrode* and an insulating agent asso contains mixture of tbe two in varying proportions ciated with each of the electrodes and isolating them from These can he readily separated from each other end from cads other, said insulating agent comprising a celiulosic. any unreacted initial material and/or from any diluent material impregnated with the present ethers. by fractional distillation. Whila tbt present condensa Example* of electrical apparatus in which the present tion reaction tales place in the absence of any extran 40 furfuryl or tetrahydrofurfuryi chlorine-substituted phenyl eous solvent or diluent, reaction may b* facilitated by ethers arc valuable component* are shown m the accom operating in the presence of an inert liquid at solvent Or panying drawing. diluent, e.g , toluene, xylene, etc. Fig. i i* a front elevation partly tn anctioo of a trans I have found that the present furfuryl or tetrahydro- former; Fig. 2 illustrates a switch in a similar manner, futfuryl ctuorivsubstituted phenyl ethers servs as very 40 Fig. 1 represents a rolled capacitor; Fig 4 shows a sec useful dielectric media when interposed is tlacmeal ap tion*) view of a portion of the electrodes and dielectric paratus between metallic conducting elements that bav* sheets of Fig. 3; and Fig. 5 n a aide view of a cable, a difference in potential during operation of the appara tbe eating being partly removed to permit th* ulterior of tus because they are very stable itqpsds which possess the parti to be seen. good dielectric strength, law power factor and good ohm W The transformer illustrated in Fig. I comprises a esatpg resistivity. They are particularly valuable ns liquid iffl- 1, cor* 2, coils 3 insulated with manila paper, krafi paper, pregnants in capacitor and cable manufacture, as trans former coolants, and in the fabrication of switch gear, cotton or other fibrous insulation, insulating and cooling medium 4, lead-in bushings J, and suitable leads 4 con Charactensiics of the present cbloro-etbert art such as nected to the coil assembly, Tbe insulating and cooling to render them particularly valuable u impregnaots for ** medium may consist of an ether such as 3-(dich)oro- crltuiostc insulating materials. It is known in the art pbesoxymelbylltetrthydrofurao which may be employed that impregnation of celiulosic materials, e.g., wood pulp as euch nr in combination with highly chionnited bi paper, cotton, cotton fabric, cellulose aeetato fibers nod phenyl inch as "Arodor" (manufactured by Monsanto '.exults, by certain liquid dielectrics provides an insulat Chemical Co., St. Louis, Mo.). The** two components ing maiensi having a dielectric constant which a much * may be employed in proportions such as from 5094 to higher than that of either lb* celiulosic material before 9094 by weight of one or mors of the present ethers with impregnation or of tha liquid dielectric. Some of tbe the balance being the Arodor. Liquid bydrnearboos or first liquids used for this purpose were mineral oils, th* dielectric strength of oil impregnated paper having been reported by Bailey (Radio Engineering, 17 17, JJ (1937)) to be 15 times as high as that of the oil alone. other hafogeoated hydrocerbon* or mature* thereof mty also be used in combination with the furfuryl or tetrihydrofurfuryl chloro phenyl ethers as dielectric media, e.g., petroleum Oil, halogeoalcd compounds of pipbthal- However, because mineral oils nr* readily oxidated, their tae, toluene, benzene, ottrobipheoyl or diphenyl oxide. usefulness as insulating media and as impregnating agent* The switch shown in Fig. 2 comprises a casing 7, Axed for cei.'ulostc materials has been limited in that exposure contacts and 9. and movable contact* 14 nod II which to air, luntigtu or moisture often leads to gaa formation, T4 co-operate therewith. The movable contact* are mounted jsseous ionization and formation of wax. Theu changes upon a tuppon 12 which in turn is operatively connected affect power factor Stability. to actuating levers II. A suitable arc-quenching hqwd Although wood pulp paper, aiona. has good insulating which may be used in Uu* device, either as the sol* di propcnica, n ts also affected by exposure to air. particu electric. or in combination with a minor proportion of a larly at higher temperatures, Whff* the rat* of nyp- Tf petroleum oil or a halogmwted hydrocarbon auch m i V li I It m P< sc *1 tn I X me tin tn , V! chit conou;! seal, A. the hou > tame. h)drr mct.t The due tot able r the iris of the fuitn, lully 3 phenyl chlorm. Tbe , the folic Tetra; benzene To i : and Dc.i: of 1,2 4. distilled C /: ;s iflt) 250 C uithn C for 5 b and 14(1 I reiultin,- r phenolph.. hyJmcMoi tilled uitti ciritatcj i, M then tied Afisyer uhi.l ll ]*(, ai comb -.ncd prod .ltd 1 0 i--i' ' q-id thuPure 2 | ; 'O'--1 JO 'C niter, bn, 192-204* C (34-140* c HONS 20175* J -h]y thloriiiattd biphenyl, >* bu(tetrehydrofurfuryloxy) 6 , cybernetic The cipaeiior shown in Fig. 3 is made up of ellernete .,tn of metal foil such as aluminum or tin foil separ- ',[i by thec's nf dielectric material. Fig 4 shows a ir. ,oa of one turn of the finished rolled capacitor illut- i n; the alternate electrodes and dielectric layers. De- t. i.s of ihe const ruction of the paper capacitor arc act (a. 'i hctc by w.iy of illustration _ Th-rc shecs of t.wue paper (preferahJy Iraft capaci- ,jr insue). arc stacked upon each other, and a thin '1!,,i'iinum foil l.ihoul 0 0003" m thickness) ts laid on the The dicthcr fraction, i.e., (II> analyzed as follows; sheet of tissue. The foil is then covered wjth three r.ofe sheets of the tissue and another sheet of the foil n , ,:cJ ibercon so that the two sheets of metal foil are Lrparated from each other by the paper The stack of , 'trusting layers of metal foils and tissues thus obu. ncd is wound into a cylindrical roll. This is placed in [ container, and at this point electrical connecting resnf, 11, wire or bar conductors, depending upon the , ;e of the essembly, may be connected to the metal foil n Inown manner After drying, preferably in a heated .,;uLm oven one of the present ethers, such as 2-<dt- BO Based on the charged 1,2,4-trichlorobenzene there was Obtained 19 4 percent conversion to mono-ether and 3 0 percent to di-ether. The 2-(dichlorophcnoxymethy))tetrahydrofuran thus obtained was found to have a volume resistivity of 33 X 10* ohm -em. at 23* C., a pour point of minus 3S* C., and the following dielectric constant and power factor values at the frequencies and tempera tures noted below; .Morcphenosymclhyllictrahydrofuran, is added to the ,'enijir.tr in a quantity sufficient to impregnate tbOf* 8# ou;hiy Ihe paper content thereof. The container it then Tim Frequency DU**;* CeoMut hv Pieter Kiitd Alrcrn^u cly, ind particulifly in lh* minufaciure of Si* 0 wo* c. 3T C W0JC. ihe small tie ms, which for Ihe sake of economy are loascd in paper tubes rather than in leak-proof con *0 1C ie 01 If ill firms, the tissue paper is impregnated with said tetra- hydio fur,in compound previous to inerleaving wuh Us* The lew power factor values at both test frequencies mtu) foil m the manner described above. and at both test temperatures show very good stability The cable of Fig 5, comprises a core 14, cable con- of the 2-(dichlorophcnoxymelhyl)lctrahydrofuran. Pow ifjciors IS. insulation consisting of paper or other suit- *6 er capacitors in which the present ether is employed for .hie material 16 and a casing 17 The space between impregnating the paper are particularly useful in that they ihe insulated conductors and the casing is filled with one may he used without freezing of the dipoles at tempera af the present ethers, e.g,, 2-[(dichlorophenoxy)melhyl] tures which approximate the low pour point of this ether fm in, or a mixture of said furan compound wth subsian- Testing of (ft). ie., the bis(tetrahydrofurfuryloxy)- lully an equal pan by weight of partially chlorinated bi* 40 chlorobenzene, also gave good results, the dielectric con phenyl having from JO to 33% by weight of combined stant and power factor values of (II) being found to ho tfclonne The invention is further illustrated but not limited by 10.3 and 1.1% respectively at 100 kc. and 23* C. It ia advanugaously employed as an arc-quenehing dielectric the following examples. in the manufacture of switches (see Fig. 2). Because Example l (It) hat a solidifying point which is approximately that of (I), a mixture of (I) and (11) may be employed as Tctrahydrofurfuryl alcohol was reacted with trichksro- the impregnating agent in the preparation of paper ca Str.rcnc as follows " pacitors as transformer coolants. To a 2-1 iter, 3-neck flask equipped with stirrer, column jid Dc.in-Stark trap there was charged 2.5 moles (434 g.) M Elxampit 2 of 1,2,4-1 richlorobenxene, 3.73 mole* (3*3 g.) of re- This example describes the reaction of 12,4-trichloro iiinlicd letrahydrofurfuryl alcohol, B.P. 73* C.-*0* benzene with tctrahydrofurfuryl alcohol using greater C/20-13 mm., 3 moles (120 g.) of sodium hydroxide quantities of reactant than those employed in Example .ml 230 g. of tolucae. The mixture was heated to 132* 1. A mixture consisting of 6.73 moles (1,220 g.) of C within about 2.0 hours and it from 132* C, to 1*0* W tbs tnchlorobenzene, 10.13 moles (1,035 g ) of said C for 3 hours. During the heating period 36 cc of water . alcohol, t moles (320 g.) of sodium hydroxide and 200 ml MO g. of tolHcoa was collected. After allowing the ml. of toluene was heated at a temperature of 140-172* 'nulling reaction mixture to cool, it was neutralised to C, for about 7 hours while collecting 134 ml. of water r'icnolphthatcin by treatment.with It ml. of concentrated- of reaction as it was formed. The reaction mixture was t..drochloric acid (equal to 0 22 mole of HCl) and di- *0 then diluted with 1 liter of water and neutralized with I icd w.th 300 ml of water, whereupon most of the pre- 0.3* mote of hydrogen chloride. The organic layer . rimed sodium chloride went into solution. The whole which separated was washed wuh water and brine and dt then diluted with about 700 ml. of ether, and flt- made alkaline to pbenolpbthalcin in order to remove it'td After allowing the filtrate to stratify, the organic any phenol which might still be present. After sub hie; which formed was separated and the aqueous layer U sequent neutralizing, filtering, and heating of the filirale j> * jibed with ether. The ether extract thus obtained at 130* C./1I mm, in order to remove water and other .i combined with the first organic layer, and the com- low boiling materials, the residue was fractionated to get ttd product was washed with about 100 ml. of water 1123 g of (I) the substantially pure 2-(dich!oropbenoxy- -ri 130 ml nf brine Distillation of the washed, orange methyl)tetrahydrofuran, BP. 133-14}* C./06-0.7 mm s'-id thus obtained gave (1) 349 4 g of the substantially 70 analyzing 53 31% C, 4 96% H, and 21.07% Cl, and ;..C 2-(dtchlorophcnoxymethyl)icirahydrofuran, BP. t* g. of (11) bn(tetrabydrofurfuryloxy)chlorobenzene, 'V'-IJO'C /0 4-| 0 mm and (11) 41.1 g. of the dt- B.P. 1*0-200* CJO.% mm. analyzing 61.00% C, 6.73% 1 cr bis(lctrahydrofurfuryloxy)ch)orobenzene, BP. H, and 11.44% Cl- Bated on the charged 1,2,4-tn- ?2-204* C./0 8-1.0 mm A narrow cut of (I) B.P. Chorobenzene, there was obtained 19.5 percent conver iid-140' c,/0 6-0.* mm., analyzed m follows; fc sion to the mono-ether tad 1.7 perusal to lire di-ether. HOMS 201755 ft.040,004 76 Example 3 chlorinated terpbeayls, chlorinated quaterphenyls, cb.'or;- A mixture consiiting of 9 moles (882 g ) of furfuryl Dated paraffinic hydrocarbons, chlorinated al.cyclic b/. alcohol, 6 moles >.1086 g ) of 1,2.4-inchlorobenzcne, drocarbons, chlorinated osygen-containing organ,c com 9.3 mole* (321 g.) of potassium hydroxide and 130 ml. pounds. chlorinated rubber, chlorinated polymers, cNo- of toluene was charged lo a 5-liter. 4-ncck flash equipped nnated fats, chlorinated vegetable oils, chlorinated arurr.ij with a stirrer, thermometer and column bearing a bead oils, chlorinated mineral otls or mixtures of one or mote for removal of condensed vapors- The mixture was of these. heated, with stirring, for about 11.3 hours at a pot This application is a conitnuaiioo in-pjrt of my cc. tempe. rature of from 130' C to 139` C. During the pending application. Serial No 330,238, filed November fin^SJtoin ofhWt.hg there* wu CoTiecl^'l's! ' 10 30r33* *nf issued as Patent No. 2,870,169 of water. When heating was discontinued, about 2 liters of water were added to the reaction mature, and the whole was filtered. After allowing the filtrate to stratify, the organic layer which formed era* separated and 1 ^ , U: *' ~leclr>TM apparatus comprising, in combinat.aa. metallic conducting elements disposed in spaced triat,on. *"'P and adapted during operation o( the washed -with water. Water was removed from the ^ *V*. * difference in electrical potential washed material by heating to 60* C. at * pressure of thertbetween and, interposed between said demean (or 30-33 mm. of mercury. Subsequent distillation of the insulating one front the other, a liquid dielectric medium heated material gave 179 g of the substantially pura 2(dUchlaropbeoosynietfayl)furan, B.P. 80* C<-115* C./0.1-0.3 mm-, ud analyzing es follows: to consisting of at least 5098 by weight of an ethtr of the formula *T Pound Oalcd, tor OoHObO i O............................................ pwtant-. a................... ......................... 4..,, KM lie MU ** in which R ii aelected from the class consisting of the tn furfuryl and (he tetrahydrofurfuryl radicals and X u The 2-(dichloropbenoxymeUiyl)furan ia advantageous aelected from the class consisting of chlorine and the radical --O--R, ly employed ai impregnating agent in the manufacture M 2. A capacitor comprising a pair of electrodes sc of cables (see Fig. 3). Although the present ethert are particularly valuable " insulating agent associated with eaeh of the electrons and isolating them from each other, tatd insulating agea: as impregnating agents for ceUuiosic materials adapted for use aa dielectrics, because of their vary good clcciricai properties, their thermal stability and their ability to remain liquid at low temperatures they are of general oomprising the dielectric medium defined tn claim 1 i. A capacitor comprising a pair of electrodes an inautiling agent associated with each of the electrodes ** and isolating them from each other said insulating agea1 utility u liquid dielectrics. Aa hereinbefore disclosed the furfuryl nr tetrahydrofurfuryl chlorine-substituted phenyl ethers may be employed per *e a* the dielectne comprising a ccllulosic matenai impregnated with 2-(di chkMophenoxynietbyDtetrahydrofuran 4. An electrical awitch comprising a pair of electrode: liquid media of elecfrtcal apparatus, or they may be ^ bis(tetrabydrofurfuryloxy)chlorobenzene assoosiec combined w.th up to subst.nt.aily equal part, by weight 40 ^ ^ JS d of one or more other dielectric liquids, such as certain liquid petroleum hydrocarbons, the partially chlorinated each other. biphenyls, trichkirobenzene, benzene, chlorinated naph thaline, chlorinated diphenyl baton*, chlorinated di phenyl oxide, chlorinated diphenylmelhane, chlorinated " Btlmscn CH*4 In the file of this patent UNITED STATES PATENTS dipheayUthano, chlorinated benzene, chlorinated toluene, 2,028,081 SternerJan. it, nh chlorinated nitrobipbenyl, chlorinated alkylated benzene, chlorinated alkylisiad biphenyls, ether triehlorobcnzene, tatrachlorpbrnrsns, ethyl peaUchlorobanzea*. 2,041,394 aark _______________ _ May 19, 193s 2,073,010. Holt 2A7Q.14* Dani Mar. 9, 193: Jan. 20, 1959 HONS 201756