Document o94JwO7YRYNKgVN88Zxovx3b8

Reprinted from: Ejvc ycl opeoia OF CHEMICAL TECHNOLOGY Edited by RAYMOND E . KIRK Hnd, Department of Qamittoy, Polytmhm InrtttvU Brooklyn and DONALD F. OTHMER Iftad, Departmanl of Ctamiml ffnftntvtnf, Pot/imhnia Inrtila/t nf Rrookiyn AtaUtant Editor JANET D. SCOTT and ANTHONY STANDEN VOLUME CAHBOiS (coni'd) to CINCHOPttEH a Pubtiahod by THE INTERSCIENCE ENCYCLOPEDIA, INC. . NEW YORK Copyrifht 1949, by THE INTERSCIENCE ENCYCLOPEDIA, INC. TMa mrtil m nr port tlirtM# mart Ml ba i>ph4um< la my Itou rttbaat par. nrtaiM of tb# puMtbar ia vriilap Thip tppttm wwlhiOy ta pba'vi rt MONS 00,036 Chlorinated Dipbujli and Related Conpoudi. The Aroclors (bred*-mark) ere chemically inert materiel* prepared by the chlorin ation of diphenyl (biphenyl) or berphenyl or more complex polypbenyls, usually with out separation of the chlorinated products into individual compounds. The form and appearance vary from mobile oily liquids to fine white crystals and hard noncrystallint resins. Beeauseof the many forms and properties, thess products have found applications in many diverts fields as in electrical insulation, nonflammable hydraulic mediums, lubricants for urn at high temperatures and pressures, and also as constituents of adhesives, plasties, lacquers, paints, and varnishes. Commercial manufacture of the first members of the Aroeior series was started in 1939, and the other Aroclors were developed soon afterwards. Physical and Chemical Properdee Since Aroclors are chemically inert except under-drastic conditions, they are of interest chiefly because of their physical properties (3). All Aroclors are insoluble in HH qQ4Q3? MGNS CKLORINS COMPOUNDS, ORGANIC TABLK L Gtntrii PuHrttw ef Same An*lore. MeWlel Vm>m Arwtur 1231 Cuhirieee mobile oil Arcelor 19M Arurfwr 1342 Arcelor 1340 Arufior 1264 Arcelor 1200 Arcelor 1303 Arcelor 1300' Arcelor 1370* Arcelor 4466 Arodur 6443 Arcelor 6400 Arcelor 3666 Almost ooiorleee mobile oil Almaot owJurlew mobile oil YkNooMmiUnI mobile oil Light yellow vieooue oil deft yellow Micky reein light yellow Micky reein Opaque yellow brittlo nain White crystalline powder Transparent yellow brittle reein Tratiapaient yellow etleky reein Yellow tntMpnnmt reein brown-black o|iat|ue reein Bear 5 DiaUlletlee FUah KI.OM Hour traini'* 1 177-1.187 376 390 l 262-1 272 200-336 141 160 176 162-164 238 CryuleU atl'C. -35 6 1 378-1 388 326-3(10 178-180 334 -- Ill 0 1 447-1 467 340-376 193-196 None -7 16381648 386-300 None None 10 1 0J8-1 929 306-430 None None 31 1 048-1 663 400-430 1 804-1 811 436-450 None None None None 37 -- t.044-1.900 450-460 None None l 712-1 723 230-330. None 1.433-1 447 216-300. 247 None >360 ~ 49 1.740-1.746 380-336. None None 1 724-1.740 None None Bofl.IMM " -- -- _ 90-99 46-50 100-106 & 90-72 1.917-1.918 1 820-1 022 I 927 t 829 1 930 1.831 1 9311-1 941 1 947 1 949 1 6601-1 6617 1 994-1 097 ~ l 990 1 906 ar *<; 40-42 47-50 89 (13 186 240 1800 26U0 - e**o. 30-31 31-32 34 36 38- 37 44 18 72-78 90-103 UO 160 (el 130*C.) 300-490 ~ A.B.T.M. D20-30. Clevelaad open cup. A.B.T.M. D97-47. " A.S.T.M. 28-42T. `Beyboll UMivereal, A.S.T.M. D88-44. ' Held uuint un euUdlAeetiaii, I36-160*C. Hold point on eiidlfioation, 249-300*C. MQNS 004038 m CHLORINE COMPOUNDS, ORGANIC water, but tbs oil* and min* are readily soluble in moet of the common organic solvents and drying oils. The hard crystalline matei vis are in general ices soluble than the oils and resins. The Arodors are permanent!., thermoplastic and may be repeatedly melted and cooled without undergoing condensation or permanent hardening. Meet of the common metals and alloys have excellent resistance to the Arodors even at ela* vated temperatures. However, copper and some of the copper alloys are affected to a limited extent, and show penetration rates between 0.0014 end 0.014 in. per year. Many plastic materials of construction are attacked by the Arodors. The general properties of the more important grades of the Arodors are shown in Table I, and Table II shows the electrical properties of those Arodors that have found application in the electrical field. Property DMsetrie ooosunt at 100 *C. sod 1000 cycke* Resistivity, ohmcm., at 100*C. tad MO volts d.e. DMsstrie usagth,* hr. Power faster, % at 100*C. aad 1000 eyoiss TABLE D. Elsetries! Properties ef Seme Areeiere. Arocior Arcater Areelar 129S IMS 1340 Amin 1344 AIrSorMlor 4.0 4.9 48 4.1-4 3 3.8-3 8 Above Above Above 900 X 10* 900 X 10* 900 X 10* --~ Above 3S Above 30 Below 0.1 Below 0.1 Below 0.1 Araaler 4441 49 Above 900 X 10* Below 0 1 A.S.T.M. D190-47T. * A.3.T.M. D149-44 usiBf a O lOfris. gap. Manufacture The pure compounds formed by the chlorination of diphenyl, terphenyl, or the more complex polyphtnyis arc crystalline solids, some of which have very high melting points (11). However, mixtures containing a number of such compounds are either liquids or noncrystaUine retina. Chlorination of aromatic hydrocarbons to various levels not only gives asveral isomers of the same chlorine content but also gives appreciable proportions of the isomers of compounds of higher and lower chlorine con> tente (17,23). At any given level of chlorine content, batch chlorinatioo*give the higtifsl proportion of compounds corresponding in composition to the average chlorine content, while single sragn continuous chlorination gives the lowest proportion of such compounds. As tho number of stages is increased, multistage continuous chlorination givoa compositions approaching thorn given by batch chlorination. Tho proportion of tho various ianmira and of compounds of higher and lower chlorine contents than the average is aim influenced by such factors as temperature, quantity and kind of catalyst employed, degree and type of agitation, and rate of admission of the chlorine. Batch chlorination has bean found moat suitable for the manufacture of tho Aroelora (23,24). Tho chloriaators are cylindrical steel towers 3 ft. in diameter and 13 ft. high, which are equipped with chlorine distributors at tbs bottom and with coils for heating and cooling the material undergoing reaction. Pumps provide agitation by HONS 004039 CHLORINE COMPOUNDS, ORGANIC 839 circulating the charge. The lower half of the chlorinators is filled with iron turnings, which have been burned free of oil and moisture. In German practice, the chlorinators are agitated 10,000-liter lead-lined vessels, and ferric chloride is used as the cata lyst instead of iron turnings. Fifteen kilograms of ferric chloride is used for each charge of 6000 kilograms (13). Raw Materials. The raw material used depends on the grade of Aroclor to be produced; anhydrous chlorine is used as the chlorinating agent in all cases. In general it can be said that diphenyl alone gives liquid or soft sticky noncrystalline Arodors up to a chlorine content of 60%, low-melting resinous Arodors between 60% and 88% chlorine content, and partly crystalline or crystalline Arodors of much higher melting points at chlorine contents above 66% (23). In the case of products that are solid at ordinary temperatures, the higher the proportion of terphenyls or more complex poly phenyls in the mixture before chlorination, the higher the softening point and the teas the crystallising tendency of the chlorinated product after distillation. For those Arodors that are solid or partly crystalline at room temperature, the higher the chlorine content, the higher the softening point and the greater the tendency of the material to crystallise (24). . Preparation of Crude Arodors. For the manufacture of any given grade of Aroclor, the chlorinator is charged with the proper raw material or mixture of raw materials to give the desired product, and in an amonnLsuficient to cover the catalyst bed and to permit circulation. Then the flow of vaporised chlorine is started end the charge is circulated with the pump. Throughout the chlorination, the temperature is kept well above the melting point of the mixture, but below 160*0, to avoid excesMve sublimation and plugging of the line discharging the hydrogen chloride produced by the chlorination. Samples are withdrawn for examination from time to time until the desired chlorine content has been reached. At the lower chlorine contents, specificgravity determinations are used to determine the composition. After the product has become too viscous or has reached too high a melting point for convenient determina tion of the specific gravity with a hydrometer at temperatures below 100*C., the de gree erf chlorination is determined by measuring the hold point in temperature as the material crystallises, or by the ball-end-ring softening-point teet (6). The time re quired for chlorination is 12-36 hr., depending upon the chlorine content of the prod uct. The anhydrous hydrogen chloride, which is evolved during the chlorination#, is absorbed in water in equipment of conventional design. DWBMtoi of Crate Product*. Although the crude product* find some applica tions, for most purposes further purification is necessary to remove the color and the traces of hydrogen chloride and ferric chloride (13,23,24). The methods of purification are somewhat different for the different types of Aroclors. The high-melting solid product* are distilled in retorts at atmospheric pressure and the distillate is flaked on chilled rolls. The liquid, and resinous Aroclors are held at an elevated temperature and blown with dried air for several hours. Then a few tenths of one per cent of lime or H"i>" hydroxide is stirred with the material to react with any remaining hydro gen chiwide or ferric chloride. This is followed by batch distillation. Complete dis tillation and mixing of the distillate is necessary in order to obtain uniform material of the desired composition. If increased electrical resistivity is desired, the material is stirred at an elevated HQNS 004040 830 CHLORINE COMPOUNDS, ORGANIC temperature with a few tenth* of a percent of well-dried fuller's earth and then filtered through paper (13,26). Containers and Shipping The liquid Aroclors are packed and shipped in galvanised steel drums or in tank cars constructed of nonmsting metaia such as aluminum or tin-coated metal. The resinous Aroclors are packed and shipped in open-top galvanised steel drums. The high-melting solid Aroclors are packed and shipped in wooden barrels. The railroad shipping classification is Resin Synthetic N.O I.B.N. Health and Safety Factors The conventional safeguards must be taken to protect personnel from the poison ous effects of chlorine. Experimental work on animals has indicated that prolonged exposure to Aroclor vapor evolved at high temperature or repeated oral ingestion of Aroclor wilt lead to systemic toxic effects. Repeated bodily contact with liquid Aroclors may lead to an acne-form akin eruption. In the manufacture or use of Aro clors, untoward effects on personnel are prevented by draft ventilation to control the vapors evolved at high temperatures, together with the use of suitable garments to prevent extensive and repeated bodily contact with the liquid products (3). Usee Electrical Application*. All of the uses of the Aroclors depend on their chemical stability and their physical properties, which may be varied to suit the specific applica tion. One very important use is as dielectric mediums in such applications aa oils for transformers and ae Impregnante for capacitors and condensers (10,11,12,15,18,21,28). Aroclors, used either alone or in blends with other materials such as thchlorobenaeoe, meet the need for a nonflammable dielectric liquid with a hi. resistivity, a high dielec tric strength, and a relatively high dielectric constant in i on to a very low power factor. The faet that the dielectric constant is higher than chat of hydrocarbon oil* and is more nearly equal to that of the solid insulation materials, such as paper, remits in a reduction of electrical straine. By substituting Aroclors, or mixtures of Aroelon with trichlorobenaene, for hydrocarbon oils, it has been possible to redesign equipment with a great reduction in sine for the same capacity and voltage. At the same time the fire haaarda hare been stimulated. Other important electrical applications for Aroclors are aa impregnants for cotton or aebcetoe-fiber "ill**1"" (22), ae constituents of ssphalt-base wire-impregnating compounds, and aa plasticisers in wire-coating compounds, particularly those contain ing neoprene, rubber, or combinations of polyvinyl chloride, ethyl cellulose, and poly vinyl butyral (30-33). Also, Aroclors an.employed ae scaling mediums for electrical insulators and aa impregnanta for carbon radio resistors to reduce the influence of moisture. Plastics, Lacquers, Paints, and Varninh*. The Aroclors are compatible with most of the common plastic materials and resins and are soluble in paint and varnish oils (3). In combination with asphalt, ethyl cellulose, chlorinated rubber, Pliotite S-5, or other plaatio materials, they are used extensively in protective coatinp for wood, metal, and concrete (3,5,6,20,28). In combination with tricreeyi phosphate or dioctyl phthalate they are coplasfcieiaera for polyvinyl chloride compositions (4). HONS 0040^1 CHLORINE COMPOUNDS, ORGANIC $31 In punts and varnishes the hard resinous Aroclors are used to impart increased hardness to the films, and the softer resins are used to give flexibility. The role of the Aroclor is similar to that of the oil, except for the fact that it does not oxidise and lose its flexibility on aging. In nitrocellulose lacquers, Aroclors are employed either alone or in combination with other plasticisers and resins to impart increased weather le9istance, luster, adhesion, and decreased burning rate (3,9,14,16). The hard, white, crystalline Aroclors of high melting point are useful as pigments with the various plastics (29). Adheaivet. The resinous Aroclors are used in synthetic adhesive compositions in combinat'on with such base materials as polyvinyl acetate, ethyl cellulose, chlorinated rubber, polyvinyl butyral, isoprene-styrene copolymer, and polyisobutyiene. LubricanU- Aroclors 1248 and 1254 find application as lubricants under extreme conditions such as highly oxidising conditions, high temperatures, extreme pressures, or submerged locations. The uee of Aroclor os the internal lubricant for high-pressure air compressors eliminates the explosion hasards in this operation (1,2). The mate rials are used also as noncombustibie lubricants for regulating the steam valves on high-pressure turbines, and in rolling r.luminum sheets. Mixtures with other oils to form heavier-than-water lubricants are used in submerged locations, such as bridge rollers. Lubricants for extreme pressures are made by adding up to 15% of Aroclor to petroleum hydrocarbon oils. The liquid Aroclors are employed as nonflammable hydraulic mediume tor trans mission of pressure or volume variations. One such application is in die-casting operations with aluminum or sine alloys, where the Aroclors replace hydrocarbon oils. The advantages are absence of fire hasards when lines break, and the fact that con densed water does not settle in the storage tanks and cause corrosion of the equipment. Another use is as the expansion medium in thermostats. Aroclors 1242, 1248, and 1254 have been found to give excellent service as circulating liquid heol-lranefer mediums for temperatures up to 325*C. Good circulation and well-designed heating systems are necessary to prevent local overheating (3). Camauba wax may be extended by blending it with Aroclors in combination with cereein and paraffin (7,19). Satisfactory waste* and poliehee are prepared without the use of camauba wax by blending ouricury (licuri) wax with Aroclors, ceresin, and paraffin. Aroclors are ingredients of many fire-reeidani competition*. Fire-retarding paints usually contain antimony oxide or barium sulfate in addition to the Aroclor. In making fireproof fiberboard, emulsified Aroclors are added to the fiber stock (27). Modifying waxes are added to the Aroclor in the preparation of textile*coating ma terials. MieceUaneou* Application. In addition to the uses listed above, Aroclors are in gredients of some sealing compounds for use with wood or canvas to give protection against moisture, mildew, or attacks of organisms. Some calking compounds and powdered metal paates contain Aroclors. Some soil-poison and wood-preserving com positions contain Aroclors as an active ingredient. Bibliography for Chlorinated Diphenyls (t) Andrews, R. W., sod Kipp, . M , .4m. Maehinitt, $8, 107 (1M4). (9) Aroetor InccmbuctibU Lubricant* Vted in High-Prtccurc Compnccura (Technical BulL P'128). Monsanto Chemical Co., St Louie, Mo , 1948. (3) Arcelor* (Appiieatioo Data Bull- P-l 15). Morunnto Chemical Co., St. Louie, Mo. MONS 004042 an (4) Arodort at CoPlaeticiieri /or Polyvinyl Chloride (Technical Bull. P-131), Monsanto Chemical Co., St. Louis, Mo., IMS. (5) .4rwJer at L'eed in Chlorinated Rubber (Technical Bull. P-124), Monsanto Chemical Co.. St. Louis, Mo.. IMS. (6) .4rocior at l'tod in Pliolilt SS (Technical Bull. P-126), Monsanto Chemical Co., St. Louis, Mo.. IMS. (7) Arodere at i'ttd to Extend or SubiMult Camauba Wax (Technical Bull. P-132), Monsanto Chemical Co., 8t. Louis, Mo., IMS. (8) A.S.T.M., Standard*. 1046, Part UI-A, Nonmetallie Materials: E28-42T (9) Bowron, H. W., Point Teeknd., 2.25-27 (1887). (10) Burnban, L. H., and Maunder, 3. T., Gen. Eke. Rm., 42,236-38 (1938). (11) Clark, F. M , Trane: Eloetroebom. Soe., 46. 59-71 (1934). (12) Clark, F. M.,/nd. Bny. CAem., 38.698-702 (1987). ____ (13) Fav, J. W. J., and Richard* J. H., "Imprecnante Used in German Paper Capaeitora." Office Tteh. Servicet Sept., PB-7S6C8 (1M7); BIOS Pinal ReptNo. 888. (14) Gardner, H. A., and Sword, G. Q., Sad. Patin KamieA Lacquer Attoe., Sei. See., Cire., No. M, 100-03 (1888). (18) Jackson, W., Proe. Roy. Sec. {London), AIM, 158-66 (1885). (16) Jenkins, R. L , and Foster, ft N.. Ind. Bny. Chm., 28, 1362-65 (1881). (17) MacMullin, R. B., Cham. Buy. Proyrete, 44. No. 3, 188-66 (1848). (18) Whits, A. H., and Morgan, 3.0., J. Franklin Inti., 216,685-44 (1883). (18) Wood, Q. W,, M/p. Channel, 18, No. 3, 98-104 (1948). (20) U.8. Pat. 1,812,732 (Jims 30,1881), J. H. Young (to H. H. Robertson Co.). (21) U.8. Pat. 1,896,180 (Dee. 16, 1981), C. R. McCullough and R. L. Jenkins (to Swann R--arch; rsasaifmd to Monsanto Chemical Co.). (22) U.B. Pat. 1,868,147 (June 14,1882), J. H. Young (to H. K. Robertson Co.). (28) U.S. Pats. 1,882^87; -388 (Dee. 27, 1982), R. L. Jenkins (to Swsan Research; msmigasrt to Monsanto Chemical Go.). (24) U.8. Pat. 1,982,400 (Dee. 27, 1982), R. L Jenkina and J. A. Sikaraki (to Swann Rsemreh; ------ !g--1 to Monanto Chsmioal Co.). (28) UJB. Pats. 1,981,978; -488 (Ost 17,1888), F. M. Clark (to GeMnd Electric Co.). (28) US. Pat. 1.9MJ09 (March 12.1888), F. M. Clark (to General Electric Co.). (27) U.8. Pat 2,080,668 (Feb. 11,1888), R. G. Quinn (to International Paper Co.). (28) U S. Fat. 2,044,806 (Jons 16,1986), W. Kceb (to Hamden Powder Co.). (28) U.8. Pat 2,077,700 (April 20,1987), E. KUos (to Du Pent). (80) U.B. Pat 2,128,187 (Sept 6,1816). E. W. Troalaadar and W. C. Wilson (to Pyroxylin Products). (81) U.B. Pat 2,180JM (Sept IS, 1888), P. M. Clark end J. H. Koenig (to General Oeetrio Co.). (82) U.B. Pat 2,141,910 (Das. 27,1882), W. C. Hayman (to Genarsl Elsetrie Co.). (8S) U.B. Pat 2,15*281 (May 16, 1988), J. G. Ford and C. P. Hfll (to Westinghouss Elsetrie end Manufacturing Co.). C. F. Booth HONS 004043 KIRK - OTHMER ENCYCLOPEDIA of Chemical Technology Presenting a comprehensive summery of tndustrial knowledge on materials, methods, processes, and equipment for the chemist and the chemical engineer. More than 1,009 authoritative articles in alphabetical ar rangement from ABRASIVES to ZIRCONIUM by experts from the American chemical Industry andfrom research institutions. VOLUME l . I tv ANTHR1MIDES VOLUME 1 ANTHRONB u CARBON-ARC Further volume* Lo appear at 7-month intervale. Each volume appraa. 9<0 paffaa 7V. X 10*/. mao per volume (Sold on aubicriptioo only; ample volume* not avauuble.) VOLUME 1 CARBON (cant'd) w CINCBOPBBN Smi ordat sr rapnsU/er dstailsd information to INTER9CIENCE PUBUSHERS, INC. 215 Fourth Avenue, New York 3, N. Y. HONS 004044 Rtprinltd Jron; IE VJC YCL OPEDIA OF CHEMICAL TECHNOLOGY Atftod by RAYMOND E. KIRK Urn*. OtptHmmi if Chmnidry, PofylmhUi ImiUmt if Brmkiyn --* DONALD F. OTHMER Rmi. Dipotmml V Canmi Afinwruif. htyimkok InHult tf Alton! Wiiori JANR D. SCOTT anrf ANTHONY STANDS' VOLUME DU to EXPLOSIONS S PubUmhodby THE INTERSCIENCE ENCYCLOPEDIA, INC NEW YOU l1M0. by THE INTERSCIENCB ENCYCLOPEDIA. INC. HONS 004045 DIPHENYL AND TERPHENYL9 Of the series of phenyl derivative* of benaene, the moat important are the lowest mem ber* of the sene*. Phenylbensene (I) is usually called diphenyl but is better called biphenyl in accordance with the l.U.C. rule for using the prefix "bi" to denote the doubling of a radical or compound (see Nomenclature). The 3 diphenylbenaenes, p-, m-, and 0- (II, III, and IV), are called terphenyls or triphenyls. Quaterphenyls and higher polyphenyls are also known. Stereoisomerism has been observed with certain derivatives of diphenyl (2,2',6,fi'and even some 2,2'-darivatives) and is attributed to restricted rotation of tbs bond between the 2 phenyl groups as a result of the presence of substituents in tbs ortho positions (1). Diphenyl Diphenyl (biphenyl (I.U.C., C.A.), phenylbensene), formula weight 154.20, is a white or slightly yellow crystalline solid, which gives plates or monoeUnie prismatic crystals when crystallised from a solvent. It was first reported in 1802 by Fittig, who prepared it by the action of metallic sodium on bromobenssns. Bertbslot In 1876, BOchner found diphenyl in high-boiling fractions from coal-tar distillation. It is used chiefly as a heat transfer medium and as the raw material for chlorinated diphenyls. Physical and Chemical Prepsrdss, M.p. 69.2C. (4), f p. (commercial product) 68.5-89.4*C., b.p. 255.2 * 0.2C., d? 1.041, d" 0.981, crit. temp. 528C., crit. premure 31,400 nun. Hg, crit. density 0.343 pam/cu.cm. (5), flash point 106C., fire point 124C. Diphenyl is one of the moet thermally stable of known organic compounds. Chemically it resembles bensene and can be chlorinated, nitrated, suifonated, and hydrogenated. Diphenyl compounds analogous to benaene compounds may usually be made by the same or slight modifications of procedures used for benaeoe. Mannfhctare. Diphenyl had little commercial value before 1925-1930, when the MQNS 004046 14$ DIFBKNYL AND TERFHENYLS first large-scale manufacture was successful. .\11 commercial diphenyl is produced entirely by the thermal dehydrogenation of bensene. Diphenyl can also be obtained by the reduction of bensenediasoniura chloride, C#H*NjCl (see Vol. 5. p. 43), and as a main product or by-product in the well-known Grignard reactions (?.v.) using phenyl magnesium halides. For the commercial production, benzene vapor at 1-2 atm. pressure is heated to 700-850C., the time of exposure to the higher temperatures being of the order of one second. Under these conditions from 10 to 15% of the bensene is converted in one pass through the reactor to diphenyl, higher homologs, tan, and carbon. The yields depend upon conversion. At 10% conversion the yield of diphenyl is approximately 0.85 lb. and that of the terphenyle and quaterphenyls is 0.07 lb. per pound of benttne consumed. At 15% conversion the yield of diphenyl is 0.80 ib. and that of terphenyl, etc., is 0.12 lb. The mechanical loss of bensene is 0.02-0.04 lb. per pound of bensene consumed. The product from the reactor is condensed, the bensene diatilled-off and recycled to the reactor, and the diphenyl purified by vacuum distillation. Bensene in the non condensable gas (mostly hydrogen) vented from the primary condensers is recovered either by compressing and cooling or by using activated-charcoal adsorbers. The re cycled bensene is very pure, as the nitrogen, sulfur, and aliphatic compounds are de composed at the temperature of the reactor. The process as outlined above is simple and gives good yields from a cheap raw material. However, the tendency of bensene to decompose at temperatures above 9fiOC. to give carbon and heavy tar depoeita on the heat-exchange surfaces of the reactor has presented a serious problem. Prac tically all of the patents covering the manufacture of diphenyl have been proposed as solutions of this problem. Heat is best supplied to the reactor usually as electric heat at temperatures above 650*C. through noncatalytio surfaces. Fuel-fired furnaces have not been satirfactory because tbs usual high-temperature alloys employed in them contain iron and nickel, which are active catalysts for promoting the formation of carbon from bensene. Fur thermore, alloys that are relatively inert for bensene pyrolysis are unsatisfactory for direct-fired furnaces because they do not resist scaling from furnace gases. A carbon-tube furnace designed so the vapors pass both inside and outside of the tubes while the tubes act as resistors is used by Williams (25,31). The bensene vapors enter the carbon-tube section at 950C. after being preheated by the reactorproduct vapors in a conventional metal tubular heat exchanger. In the carbon-tube reactor (tubee 1 in. O.D., 0.75 in. I.D.) apparent overall heat-transfer coefficients of 100 B.t.u./(eq.ft.)(hr.)(F.) arc obtained, at a mam velocity through the tube of 7 lb./(sq.ft.)(sec.). In this reactor the temperature of the bensene vapor approaches within I0*C. the temperature of the carbon tubee. Alternating current at 40-60 volts is used to beat the carbon tubes. Williams (30) has been able to improve the operation of this unit by adding to the bensene stream 0.1% sulfur as a volatile sulfur compound such as hydrogen sulfide, carbon disulfide, or sulfur dioxide. The addition of sulfur reduose tbs deposition of carbon in both the carbon-tube furnace and in the preheater. Carothere' reactor la similar except that solid metallic resistors (Nichrome) are used to supply heat above 650C. (19). He emphasises the importance of high vapor velocity at the heating dements and gives 1.24 seconds as the maximum time in the reaction sons. The I. G. Farbeninduetrie diphenyl plant at Leverkusen used copper-tube reac tors heated by external electrical resistance elements to produce 27,000 lb. diphenyl per HQNS 004047 DIFHEXYL AXD TERPHMNYLS 147 month (0). Lowdermilk and Turncock (9) and a BIOS Report (3) state that two batch unite were installed, one producing 32,000 lb. per month and the other 80,000 lb. per month. A third, to produce 150,000 lb. per month, was under construction. The reactor wee a copper-alloy tube containing 3% manganese electrically heated by ita own resistance. Operating at 790-810C, these reactor coils had a life of eighteen months. All-copper coils lasted only a few days in this type of reactor. These units were batch units in which a kettle was loaded with benzene and the vapors were circulated through the system by boiling the bensene in the kettle. The vapors were circulated for eight hours, then the batch was transferred to a still. Thio phene-free bensene was used in this copper equipment. A number of attempts have been made to reduce catalytic activity of ferrous surface* so that conventional fuel-fired furnaces can be used. Among the suggestions that have been made are coating the walls with antimony pentasulfide, sine sulfide, iron sulfide, or cobalt sulfide (15,29); nitriding the iron surface by treatment with ammonia (34); and forming a carbide surface on the iron tube (38). In any of the proceeses using solid surfaces to supply heat to the reactor it is essential that surface temperatures be kept as low u possible, by using low-heat flux through the surfaces and maintaining high gas-film heat-transfer coefficients at the surface. While the re actor is at cracking temperature, steady flow conditions must be msintrimri all times. The use of solid heat exchange surfaces in contact with bensene vapor* has been avoided altogether by bubbling the vapors through an inert liquid bath maintained at 750-850'C. Lead has been suggested as a suitable bath material (12,19,23,24). Theee lead-bath reactors were probably the first successful commercial reactors. The construction and operation of a laboratory apparatus with a lead-bath reactor has been described (7). One and one-half to three volumes of liquid bensene per hour per volume of lead was used, and by operating at higher pressure, 125 p.s.i., increased con version, capacity, and yields could be obtained. The use of an inert inorganic salt bath, particularly a mixture of sodium and calcium chlorides, has also been suggested (21). Heating bensene vapors through surfaces can be avoided by miring bensene vapors at 650C. with sufficient steam superheated to.9fi0-1150oC. to produce, a mixture at 750-850*C. (26) in a reaction and mixing chamber coated with a layer of magnetic iron oxide. This proosaa differs from all the others in that the bensene losses to terphsnyl, etc., are very low, and also in that phenol is produced as a by-product. When compared to other well-known dehydrogenation or cricking reactions, the bensene diphenyl reaction is relatively insensitive to catalysts. No catalyst reported to date lowers tbs reaction temperature, and the data available do not permit an evaluation of the effect of a catalyst on the ultimate reoycle yield of diphenyl from bensene. The high yield (up to 85%) of the uncatalysed thermal reaction does not leave a wide margin for improvement. However, increased conversion at the usual reaction temperatures has bssn demonstrated. Up to 200% increased conversion (from 10 to 90%) per pass has been Claimed by adding to the bensene vapors 0.1-1% of a volatils aliphatic compound containing at least one oxygen atom (39). Suggested mettriak are alcohols, ethers, or ketones. Surface catalysts recommended are mag nesium, aluminum, or copper silicates (21), fire clay (18), and lustrous carbon on which either magnesium, tungsten, or aluminum oxide singly or in combination baa been deposited (13,14,17,32). A pumice catalyst has been used with a mixture of bensene and steam at 700*C. and 60 p.e.i.g. (20). HONS 004048 149 D1YBKNYL AND TMRFBENYLS Bensene can be converted to diphenyl in an electric glow discharge at low temper atures (38). Diphenyl is also produced as a by-product from the manufacture of phenol by the direct air oxidation of bensene carried out in a special reactor designed to reduce to a minimum surface oatalytic effects (41). In 1949. the price of diphenyl was 154 per pound with bensene at 224 per gallon. If a very large demand develops, it seems quite possible that large plants using some of the recently developed equipment and techniques, such as moving-bed pebble heat ex changers or the direct oxidation of bensene to phenol and diphenyl, might permit lower prices. Uses. Diphenyl-impregnated paper wrappers for citrus fruits are used to reduce storage and handling ioases (10,11,39). Diphenyl is used either alone or mixed with phenyl ether (diphenyl oxide), (C*H*)*0, as a low-pressure, high-temperature beattransfer medium (see Hat (roaqfsr). Derivatives* Of the derivativee of diphenyl the chlorinated diphmyl* are probably the moat important commercially (see Vol. 3, pp. 820-32). The 2- and 4-mononiiro and menoamino derivatives are prepared from diphenyl in the same manner ss nitrobenstne (g.v.) and aniline (f.*.), respectively, are made from bensene (8,22,27): 2nitrodiphenyl, m.p. 37.2*C., f.p. 30.9*C., b 201.0-201.3*0., sp.gr. 1.44; 4-nitrodiphenyl, m.p. 113.7*0., f.p. 113.8*0., b 223.7-224.1*0.; 2-aminodiphmyl, m.p. 49.3*0., f.p. 48.7*0., b 182*0.; 4-aminodiphenyl, m.p. 54.1*0., f.p. 510*0., b 211.0-211.2*0. Tbm 4,4'-dlammo derivative, NH^HCiH^H,, called bensidine, is an important dye intermediate (see itatsiduw and related dsamsnodtphenyic, Vol. 2, p. 448). 4-Hydrcaydiphtnyl (p-phenyiphenol) (m.p. 104-105*0., b.p. 300-300*0.) may be mads by tbs conventional phenol procses through sulfonathm and caustic fusion (40), by substituting diphenyl for bensene. The p-phenyiphenol-fonnaidehyde condsnsation product is used as a lacquer resin. The ndfonakd and attyfafsrf deriv atives of diphenyl are useful as wetting agents (35,37). For hydrogenated derivatives ssa p. 101. Tbs three isomerie terphenyls (diphenylbenssnec, phenyldipbenyls, triphenyls, Santowaxas), CiHgCiH^CsH* formula weight 230.29, occur in the form of white crystalline solids when purs. The commercial grades are light yellow. Although m- and p-terpbenyi were prepared by synthesis and were also separated from tare and from tbs residues from diphenyl preparation by earlier workers, there was no extensive study of their properties until 1927, when Bachmann and Clarke pre pared pure lamp!is of tbs throe isomers and determined their melting and boiling points (48). A few yean later the materials became available as by-products from the manufacture of diphenyl on a commercial scale. The principal uses of the terphenyls m eueh are based on their stability and high boiling points. Phjrieal and denial Prspsrtiis. Table I gives the physical properties of the purs terphenyis (48,50,51). Table II gives the physical properties of the commercial grades. The solubility of the commercial grades in various solvents is given in Table III and tbs compatibility with various waxes and resins in Table IV (48,49). All of the isomers exhibit unusual stability toward beat. They are also stable in the pres ence of boiling 10% ***" hydroxide or boiling 10% sulfuric acid. HONS 004049 DIPHENYL AND TEHPHENYLS 149 The terphenyls undergo the usual organic reactions of aromatic hydrocarbons and can be chlorinated, nitrated, sulfonated, and hydrogenated. Extensive studies on the preparation and reactions of o-terphenyl have been made and a number of derivatives e-Terpheoyi e^Terphtayl ^Terpheoyl TABLE L Pkrefcal Preserves of Pur* Tsrphsarla. Mg.. CrrabU SeiubUiiy 57 332 Prisms Somewhat soluble ia ooid methanol: readily soluble la beaeaae, acetone, aad chloroform 87 306 Nesdks Slightly soluble la hot aleabol; soluble ia beoseae, ether, aad acetta add 213 376 Moaodiale Slightly soluble in boiling benseoe or boiling prisms ether; almost insoluble in boiling alcohol TABLE IL PlnW Fftpergsa of Ceauterdal-Crade Ttplu^k Nurtr ^Tepkiirl' (SastewM 0) ("S*uTlierpwh--uMyl*) Melting range, Distillatioa range, *C. (A.8.T.M. D30-80) Vapor pressure, mm. Hg At 100*C. At 180*C. At 900*C. At 380*0. At 800*C. At 300*C. At 8I0*C. Deadly at 96*C. Flash point, *C. Flu. point, *C. Dielectric oomUnt at 100*C. aad 1000cycles RariMlvHy at 100*C., ohm-cm. 50-66 380-841 75-86 368-378 0.3 3.7 25.0 110 0 800.0 MOO 1600.0 1.14 171 198 3.54 8300 X 10* 19 9.8 48.0 180.0 500 0 870.0 1.164 307 339 2.63 3600 X 10* Coatelas asms et-tsrpbsajHL * Coatelas ooom > sad ptmphmyls. 4 At 250*C. 200-216 381-386 0.3 5.5 35.0 130.0 390.0 880.0 1.398 307 238 -- 30 X IV* MwlupSsIm--jmnM (9mM>u X) CO-146 364-418 13 9.8 48.0 180.0 500.0 870.0 1.138 191 238 3.50 140,000 X HP TAMJDL Ee^By st CwmmtiHtl fitade Teepheayto la srisas flefreals, lilwil 3A Baassaa Stoddard eelvesA Triehiscebamsms Turpsadas Otoaa W MrpOMjrl par 100 at. wt mtwwmt -T-mad At M*C. ai arc. --Twphwt At U*C. At 70*C. e-TweStad At U*C. At rs*c. 8 31 800 540 --. -- 316 530 380 540 1 30 a 30 4.5 7 380 63 246 M 0.01 0.9 0.2 0.8 0.2 0.2 5.9 1.1 6.6 13 prepared (43). When concentrated solutions in bensene were refluxed for a short time with a very little aluminum chloride, up to 94% of the o-terphenyl was converted to m-terphenyl. Longer times of reaction and the use of higher aluminum chloride con centrations resulted in the conversion of as much as 84% to p-terphenyl. HONS 004050 m DlfBINYL AND TERFBMNYLS Mon attention bn been given to the study of p-terphenyl then to the other iaomen and it haa been prepared by ten methods (46,55). Nitro, amino, halo, hydroxy, methyl, and hydrogenated denvativee haWbeen prepared and their proper ties determined. Wb or natal Pemflta Ceraauba CandsUUa Pemdme No. 1 Blown Japan wax Opel wax Shrike Mead* raria BMrgum r-Torphowt, % 90 -- -- -- 50 -- 10 -- -- "-TarptaMyt, % <2 75 __25 10 25 10 10 10 __p-Torhoirt, % _ _5 _ __ _ - The terphenyk may be eyelohexylated by reaction with cyclohexane, cyclohexyl chloride, or eyclobexanol in the pretence of aluminum chloride or other alkylation eatalyete (54). When mixed ieomers an used, the product is a waxy solid which is useful as a plasticiser. It distilla at 285-310C. at 5 mm. preaeum and congeals at about I10*C. A solution of sodium in liquid ammonia reacts with p-terphenyl to give dihydro- terpbenyl, ntp. 70*C. (47). Many hydrogenated derivatives of p-terphenyl have been prepand by reactioa with hydrogen under preecun in the pretence of nickel or aome other hydrogenation catalyst (46,59). When vapore of terphenyk an with hydrogen and heated to 65O-B0OC., benacne and diphenyl are formed (59). Beet results are obtained by using four or five moles of hydrogen per mole of terphenyl. MandMtvs. The high-boiling by-products from the manufactun of diphanyl give tha only commercial source of raw materiak for the preparation of terphenyk. At the prseent time this eouroe k adequate, and if the future demand for terphenyk should ineneee, it can be met by raising the temperature at which diphenyl k prepared, with the resultant formation of a higher proportion of terphenyk. After the seperatkm of the diphenyl, the high-boiling by-produete contain approx imately 9.0% o terphenyl, 40.0% m-terphenyi, 33.0% p-terphenyl, and 30.0% triphroykos (0,10-beneophenanthrone), quaterphenyk, etc. If mixed terphenyl komers are desired, the high-boiling material la melted and charged to a still constructed of steel. Distillation k carried out at a low reflux ratio using a 13-plate column. During tha distillation tha pressure k 100 mm. Hg at the top of the column and approximately 139 mm. Hg in the boiler. The distillate k condensed, and the resultant liquid is either flaked on chilled roUs or solidified and crushed. This procedure gives substan tially complete removal of the triphenylene, quaterphenyk, and other residues. If t-ptm**"" of the ieomers is desired, the operation k much more difficult sinc^ oterphenyi and m-terphenyl are difficult to separate by fractional distillation becsust of tha small proportion of o-terphonyl preaent, and m-terphenyl and p-terphenyl cannot be separated by fractionation in a column of any practical height. The distillation k carried out by using a reflux ratio of 10:1 or higher to give an o-terphenyl-rich fraction MCN5 004051 DIPHENYL AND TERPHENYLS 151 containing less than 60% of o-terphenyl together with m-terphenyl. This ie followed by an intermediate fraction and then by a fraction containing only m-terphenyl and pterphenyl. The o-terphenyl fraction ie enriched by redistillation to give a product containing in excess of 90% o-terphenyl. The intermediate fraction and the residue from the redistillation of the o-terphenyl fraction are recycled. The final separation of m-terphenyl and p-terphenyl is effected by centrifuging at a temperature slightly above the melting point of m-terphenyl. Similarly, centrifuging at a temperature slightly above the melting point of o-terphenyl results in further separation of m-terphenyl from the o-terphenyl. If additional quantities of either m-terphenyl or p-terphenyl are needed, and other terphenyls are available, the desired material may be prepared by an isomerisation process (57). Any terphenyl or mixture of terphenyls is heated with 1-3% of alu minum chloride for about one hour to form an equilibrium mixture containing 65-70% m-terphenyl and 30-35% p-terphenyl. If m-terphenyl in desired, the reaction product is cooled quickly, by mixing with ice, and the aluminum chloride is removed by treat ment with hydrochlorto add and filtration. Then the m-terphenyl and p-terphenyl are separated. If p-terphenyl is desired, the reaction product is cooled to 9<M65*C. and held at this temperature while p-terphenyl crystallises. Yields of over 90% of p-terphenyl may be obtained in this manner. Freedng-point or melting-point determinations are the chief criteria of purity for the pure ieomere. Fractional distillation ie necessary for analysts of the mixed isomers. The terphenyls are sold as crushed or flaked yellowish-colored solids. They are shipped in wooden barrels or fiber drums and are available in carload lots. The ship ping classification ie Coal-Tar Resin. In 1949, the approximate price for the mixed ieomerio terphenyls was 174 per pound in ton lots. Uaea. The terphenyls are useful aa heat-storage and heat-transfer agents (53, 53). The vapor premure does not exceed atmospheric pressure until temperatures above 30OC. are reached. The stability of the terphenyls renders them useful as high-temperature lubricants. They are of value also as constituents of waxm and polishes and at plasticisers for resin-bodied paints. Derivatives. The chlorinated and hydrogenated derivatives of the terphenyls have found extensive application. For chlorxnaUd derivatives, see Vol. 3* p. 836; for hfAroggnaUi derivatives, see below. Hyfceg--M Pmhatives of Diphenyl aad Terphenyls Diphenyl or terphenyl may be hydrogenated to form a number of derivatives of which three are of commercial Importance. Cydohtsqftbmatn (phenylcyclobsxane), CHuC*H, formula weight 160.36, is formed by hydrogenation of one ring of the di phenyl molecule, end Wflyeiehmyf (dicyclohexyl), (C*Hn), formula weight 166.30, ie formed by complete hydrogenation of diphenyl. A partially hydrogenated mixture of iaomerio terpbsnyls ("HB-40") is the third product of commercial importance. All of the an high-boiling liquids, with freeling points well below normal atmospheric temperatures. The principal uses are as solvents and plasticisers in the plastics, coating, and adhesive fields. Phyrical and Chemical Properties. The properties of pure bicyclohexyl, cyclo- hexylbenseoe, end a number of hydrogenated compounds derived from p-terphenyl are given in Table V (45,47,50,60). The properties of commercial grades of bicyclo- MQNS 004052 m DIPHENYL AND TERPBBNYLS TABLE . Pupirtw af DariradrM of npbaji sad p-Tarphaayl. Compvuid M p.. *C. B.p.. *C. Deeaty Bioyclohsxyl................................ CyolohsxylbsDMD*..................... Dihydro-p-UrptMQyl................... Tstrahydro-jMarphaayl.............. Hexahydro-^tarplMayl.............. OcUbydro-yUrphanyl............... Dseahydr>ptMplMayl.............. P'DtayalofacxylbtnMM............... Dodacshydro*p*ttrphaoyl.......... Stereoisomer*.......................... Haxadeealtydro-p-terphsnyl....... Octadeeahydro^terphenyl........ Stereoisomer*.......................... 3.5-4.0 7-8 70 145-148 85 no 97-48 101 80 Liquid 111--113 55-57 163 230.5-340 233>234tm -- -- -- -- 225~230ii -- -- 144.| 190. -- - 0 8835* 1 0.047" i.rar -- -- -- _ _ _ _ _ - * Rssrrsogvs os bsatinf with carbon disulfide sod aluminum chloride. ' Rsarrangsmset could not bs effected. Mmda iadm l.mC 1 5174'; _ __ _ _ __ _ - TABLE VI. Properties ef Commercial-Grade Predsats. Bi*rioAnrt CwWaUMbIaMsr*- Appearance......................................... Odor.................................................... as....................................................... .... F.p., *c............................................... .... Praasins ebaraetariatica..................... 1.4790 0.884 3.0 -- 1.5905 0.035 4.8 Distillation moa, 8-45%, *C............ .... Flskt poiot, *C................................... .... Flame poiot, *C................................. .... VJeoosUy, 9aybo)t uaiveraal woods At 100*F..................................... .... At 210T..................................... Pour point, "C. (A.S.T.M. D07-W).. Coot, of orpansion, ml/ml./*C........ DWostrio ooastaat At 36*C....................................... At 100*0..................................... ... Dtaketrio stieefth at 3I*C., kv.......... wmmiiiamx.tkw.......... .... Power faster at 100*C. sad 1000 sysks, % 238-940 101 104 34.3 -- 4xio -- 330-341 00 104 31.3 -- -- -- -- -- -- ;11.4 X 10** -- HB^O Clear oily liquid Psint sad plssssst 1.5675 - 0 0075 1.004 * 0.003 _ Fsw oryslals form atOto --6*C. 340-333 174 108 *8 144 *30 30 * 1 -35 * 1 0 000741 3.5 2.4 30 I X 10 0.13 hexyl, eyeloboxylbeuaDS, and HB-40 an shown in Table VI (62). Tbs hydrogenated derivatives of diphenyl and terpbenyl are not soluble in water, but are soluble in, or with, many organic solvents and oik. HB-40 is miscible at 25C. with many solvents and oik including methyl abietate (Abalyn), acetone, benaene, carbon tetrachloride, castor oil, ethyl ether, ethyl acetate, linseed oil, mineral oil, solvent naphtha, and turpentine. It dissolves in ethyl alcohol to the extent of only 6% by volume. Table VII shows the solubility of a number of natural and synthetic warns and resins in HB-40 and Table VIII shows the compati bility with several plastic materiak. HONS 004053 ftoteW AorawaiC Beeswax Caodelllla Caraauba Mootaa DlFBMNYL AND TBRFBENYLS ISI TAILS TO. Ssfabfllty ef Wises sag Rests* ta HB-4S. SetuMUty Mut Temper* eture, *C. 100 <3.0 45 3.0 40 5.0 50 3.0 50 5.0 Naphthalene Nonaethylene glycol hexarioinoleate Santowax O Santawax M Santowax P 35 25 25 35 51 SeluNUtjr. wa* 30 0 >50 0 >30 0 >10.0 5.0 TABLE Vm. CsiparthUHy * HS-SO wtth WssUs Metadata. PtaWta MtsU PerWef HkU 100 parte el pfaMla Pleetle Mteriei TJptreett&te T Butvar, low FVOH (polyvinyl butyni).. Cslluloss oitrata, 30-30 see., .......... 10 Chlorinated mbbor............... .......... 100* Ethyl osUukss (Dow Stand- ard)........ Formvar, typo E (polyvinyl... formal)................ ... Polymethyl methseryleta....... ... Polystyrene............. Vinylita VYNW . .. 30 30 Form a eticky prodoot; mar ba even mor* compatible. Mantectm. Bicyclohexyi and cyclohexylbensene have been prepared by a number of methods. In 1907, Ipatieff reported that reaction of diphenyl with hydro* geo at a promuie of 110-190 atm and a temperature of 200-250C., in the preeence of nieket compounds, resulted in the formation of bicyclohsxyl. Sabatier and Murat formed both bieyclohaqrl and cyclohexylbensene by the reaction of diphenyl with hydrogen In the preeence of nickel. Complete hydrogenation of mixed terphenyl isomers gives a waxy solid, but in* complete hydrogenation may be carried out so as to form a liquid product (HB-40) of high boiling point, low vapor pramure, end unusual solvent properties (58). In the commercial preparation of tide liquid, mixed isomeric tarphenyls are melted and charged to a stirred steel tank. The spent nickel catalyst from a previous bateh is added end the mixture is stirred under s hydrogen atmosphere and at about 200*C. for about two hours. Stirring is stopped, sad after the catalyst settles it is drained from the bottom of the tank. Unlsm the foregoing pretreatment operation with spent catalyst is employed, the quantity of fresh catalyst needed is considerably greater. Two per eent of lint nickel catalyst is added and then the terphenyl containing tha niekel catalyst in mapmskm is pumped into a stirred steel autoclave equipped with cooling ooib* and is treated with carefully purified hydrogen at 20O-2SOC. and 300-900 p.s.L Tbs innatlon is enotbsrmie and the heat released is removed by water that circulated through the cooling coils. The time required for hydrogenation varies be* tween 2 and 8 homo, depending on the purity of the materials. Samples are withdrawn from the autoclave from time to time and their density is determined. When the density has fallen to 1.004 * 0.003 at 25/15.6C., the reaction is considered complete, and the hydrogen in the autoclave is vented until the pressure falls to 26-50 p.a.i. Then the contents of the autoclave are emptied into a separation HONS 004054 164 DIPHENYL AND TERFBBNYLS tank, and the spent catalyst which settles is separated for use in the pretreatment of a subsequent batch. The supernatant liquid ie transferred to a clay treatment tank, when it ie agitated for 30 minutes at 100C., with 0.3% of dried fuller's earth. Then it is Altered, using paper as the filter medium, to give the finished product. If bicyclohexyl or cyclohexylbensene is the desired product, diphenyl inetead of mixed isomeric terphenyls is used as the starting material in processes similar to the process for HB-40. The products are packed and shipped in galvanised steel drums or in steel tank cars. The railroad shipping classification for dicyclohexyl and phenylcydohexane is Chemical N.O.I.B.N., a[nd for HB-40, Pyroxylin Plasticiser. Health and Safety Factor*. As in other processes employing hydrogen under pressure, it is essential that the equipment be designed with adequate safeguards. The explosion disks must vent the hydrogen outside the building in the event of rup ture. All equipment must be swept with inert gas before hydrogen is admitted. Also, the spent catalyst is a potential hasard, since on exposure to air, it may develop heat by rapid oxidation and set fire to any combustible materials with which it is in contact. HB-40 itself offere no particular hasards since it has a high flash point and tests have indicated that it ia practically nontoxic. Uses. In the piaatios field, the hydrogenated diphenyl and terphenyl derivative*, particularly HB-40, are of interest for use with polystyrene, vinyl resins, ethyl cellu lose, and asphalt compounds. HB-40 is of especial value ae a constituent of poly styrene emulsion adhesives and as a softener for rubber-type compounds. It is used as a high-temperature lubricant for chain drives on bakery ovens, because of its lubric ity, its nontoxic qualities, and ita lack of odor. As a heat-transfer medium, it ie used in melting-point baths where temperatures exceeding 300C. are not desired (01). It is also useful ss an actuating medium for thermostatic controls. Bibliography DIPHENYL (1) Adas* It, and Ywn, H. G, CStm. Rm., 12, 261 (19M). (3) Baflstete, 4lh acL, Vot V, p. STB; 1st Suppl.. Vot. V, p. 271. ( BriL /imflfcms* OltfaetfMS SubmmmUtm As*., 666 (1B4B). (4) ------ . J.. sad Niter, S. B., Zed. Is#. Chm, 21.1106 (1926). (6) Cork, J. Rm. Sti. Immmmtt, 1, 666-66 (1960). (6) Curd* F. 1., mi Folgw, M. P., "MiaaalUiwwia Chamteate, I. O. Farbaninduatria A- a, Bbar- fM md Lmrkma" OJks Tmk. Smiem RtpA, PB-9S0 (1946). (7) W--, A W.r Week, L. T., itII--nriinei. H. V., Clifford, O. B., and WQkae* O. A., Ind. Jhf. CAma, And. Md., 2,266-91 (1661). (6) JsattM, R. L, MeCuDough, C. R., and Booth, C. F., Ind. Mnf. Chmn., It 31 (1SSO). (9) Lmdemdk, F. B* sad Turncock. L. C., "Diphenyl Product, 1.0. Farbaniadustria A-O., Lavas* knsm," 0m Ftot Smirni Aapi. PB-4617 (1946). (10) Msdatnih, F. C, Am**, 70.264 (1944). (11) *-------r. G B., taith, M. A, and Haibatf, B. C., Sates, (ku., 196,74-62 (1944). U9) Brta Paa 3)2,906 (June 3,1926). T. 1. Scott (to Fadaral Phosphorus Co.; raaadgtacl to Mon santo Chsmteal Co.). (19) BHt PM. 3W.1S6 (May 2, 1930), O. Droaabeob and B. RoaU (to I. Q. ParbankxL). (14) Brit. PM. 300.612 (Dm. 17, 1630). I. Q. Farbanind. (15) Ft. Paa 716,017 (April 9, 1M1), Fedwal Phosphorus Co.; reawigned to Moamato Chsmknl Os. HUNS 004055 DifBMSYl AND TSRfHBNYlS 158 (19) Gar. Put. 091,006 (Fab. 1, 1939). T. J. Seott (to Fadaral Phosphorus Co.; rr--ipiwl to Mooonto Oimiwl Co.). (IT) Ost. PM. 066,079 (Dm. 17,1939), O. Dvombaeh and E. Roott (to I. G. Fubnind). 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Booth (Terphenyls; Hydrogenated Derivative*) HONS 004057 KIRK - OTHMER ENCYCLOPEDIA of Chemical Technology Preeentlng a compreheneieo eummary of in- duetrtal knowledge on iMltrUi, method*, proc****, and equipment for the chomiat and the chemical engineer. Mora than 1,000 authoritative article* in alphabetical ar rangement from ABRASIVES to ZIRCONIUM by expert* from the American chemical induetry andfrom reeearch institution*. VOLUME l A te ANTBRIMIDZS VOLUME 1 VOLUME I CARBON leaned) aa CINCEOPBMN VOLUME 4 CINMOLX te DMXTROSB VOLUME 2 01- to MXPLOSIMS Complete is 12 volumes Each volume approrimataly MS pajas 7*/. X 10*/. Richly ilhiatratad SuhacriptioD Price: 220.M per eofamc Price after completion at Encyclopedia: 222.22 per tehm Smd adae m repmdefer deoiled iefemakn te entkbsciknge publishers, dic. 31S Fourth Annit*, New York S, N. Y. nous 004058