2,2’-DiphenicAcid from Phenanthrene Laboratory studies are reported on a direct one-step oxidation of technical phenanthrene (90%) to high purity 2,2’-diphenic acid using both in situ and prepared peracetic acid, relatively short contact time, and in 65 to 70% yields. With prepared 4ov0 peracetic acid, maximum yields of a high purity product were obtained using dimethyl cellosolve as solvent, reflux temperatures, and mole ratios of 10.0 to 1 of peracetic acid to phenanthrene and 14.6 to 1 of dimethyl cellosolve to phenanthrene. *Basedentirely on laboratory data for the prepared peracid oxidation technique, a batch semipilot plant was designed, constructed, and successfully operated to yield a maximum of pound of 2,2’-diphenic acid per run at an estimated materials cost of $16.00 per pound. Solvent recovery was effected by azeotropic distillation and by-product anthraquinone was recovered in 54 to 60% yields. WILLIAM F. O’CONNOR
AND EMIL J. MORICONI’ Fordham University, New York, N . Y .
P
’
H E N A N T H R E N E is one of the three main constituents of the anthracene oil fraction (300’ to 350’ C.) of coal t a r distillation. Although i t may be extracted without much difficulty, it i s not usually separated because neither it nor its derivatives have been found of sufficient commercial value t o warrant the expense of their manufacture (18). I n 1951, some 70,000,000 pounds of Phenanthrene were available but were never removed from coal tar. This tremendous potential of phenanthrene led us to examine it as raw material for the preparation of its secondary oxidation product, 2,2‘-diphenic acid (2,2’-dicarboxybiphenyl).
rier and Moggi obtained 2,f‘-diphenic acid in 29% yield accompanied by a considerable proportion of tars ( 2 7 ) ; later, Boeseken and Slooff duplicated their work (1%). A catalytic air oxidation of phenanthrene in both liquid and vapor phases was investigated by Zalkind and Kaserev (57) and resulted in small yields of 2,2’diphenic acid. The most recent work has been t h a t of Cook and Schoental who obtained a l6Y0 yield of phenanthrenequinone and a negligible yield of 2,2’-diphenic acid using a 20% hydrogen peroxide solution and a n osmium tetroxide catalyst (19). It is worthy of note t h a t the present-day cost of 2,2‘-diphenic acid is approximately $115.00 per pound (20).
PREVIOUS STUDIES
PRELIMINARY INVESTIGATIONS
The most successful of preparative methods for 2,2’-diphenic acid have been coupling of suitably substituted benzoic acids and their derivatives (5-8, 13, 31, 32, 48, 52, 54). The maximum yield obtainable by these methods has been 90%, but it has been offset by the high cost of the reactants and subsequent processing. Alternatively, 2,2’-diphenic acid may be prepared by the oxidation of phenanthrene or its primary oxidation product, phenanthronequinone. Phenanthrenequinone, as the intermediate in the two-step synthesis of 2,2’-diphenic acid, has been accomplished by a variety of methods from phenanthrene (2, 9, 10, 26, 13, 65, 68, 33-37, 39, 42, 63,55). The final oxidation step has been carried out by treatment of the phenanthrenequinone with fresh, additional quantities of the previously mentioned oxidizing agents (6,16, 66-25, 68, 30, 34, 35, 42, 43, 46, 53) or other oxidants ( 1 , 3, 1 1 , 15, 38, 40, 56). Yields of 2,2’-diphenic acid from any combination of these two-step ox,idation procedures have never exceeded 56%. I n addition, the oxidations invariably are time-consuming, require large excesses of oxidizing agent with its concomitant cost, include much tar formation, and oftentimes necessitate tedious working-up procedures. The direct one-step oxidation of phenanthrene t o 2,2’-diphenic acid has been accomplished electrolytically by the German firm, Meister Lucius and Briining (37). Yields and experimental details are unrecorded. The first chemical method was t h a t of Charrier and Beretta using alkaline permanganate (15). Their work was repeated and improved upon by Randall and coworkers who, using a 3.5-gram sample and a 40-hour reflux time, obtained a 46% yield of the acid and a 30% yield of phenanthrenequinone (44). Using 30% hydrogen peroxide in glacial acetic acid, Char1 Present
address, Marymount College, 221 East 71st St. New York 21,
N. Y. February 1953
The process development problem was twofold:
1. The development of a commercially feasible laboratory process for the one-step oxidation of phenanthrene to 2,2’-diphenic acid. 2. The translation of this laboratory process t o t h e design, construction, and successful operation of a semipilot plant for the production of 2,2’-diphenic acid. The oxidizing action of aliphatic peracids has long been known (21, 69, 47, 50, 51). However, economical preparations of con-
centrated peracid (performic, peracetic) solutions became feasible only with the recent commercial availability of concentrated 50 and 90% hydrogen peroxide (66,27). The equilibrium reaction may be formulated RCOOH
+ 90% HgOn F’c RCOOOH + HzO
It was observed in the early stages of this work t h a t 50% hydrogen peroxide in glacial acetic acid would oxidize phenanthrene to high purity 2,2‘-diphenic acid in a relatively short contact time and in 65 t o 70% yields (41). The over-all reaction is presumed t o he
+ 4CHaCOOOH -AI
+ 4CH3COOH
Two general oxidative techniques with peracetic acid were then available for study: 1. An in situ method employing an acetic acid solution with or without 1% sulfuric acid catalyst
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sodium salt) since the excess peracetic acid was destroyed a t the reaction temperature. The solution was filtered on cooling and boiled with charcoal, filtered again, and acidified with concentrated hydrochloric acid Purification with charcoal was usually unnecessary in the prepared peracetic acid method. The desired 2,2'-diphenic acid crystallized on cooling to yield 65 t o 70% of creamy white needles, melting point, 228' to 229" C. The alkali-insoluble material was recrystallized from boiliiig glacial acetic acid to yield by-product anthraquinone. Solvent recovery in the prepared peracetic acid oxidation 1% as effected by azeotropic distillation of the mother liquor from t h e 2,2'-diphenic acid crystallization. Variables of in Situ Reaction. The effect of mole ratios of hydrogen peroxide to phenanthrene and acetic acid to hydrogcri peroxide on yields of 2.2'-diphenic acid are shown graphically i n Figures 1 and 2. Maximum yields of a pure product were obtained using mole ratios of 14.0 to 1 of hydrogen peroxidr to phenanthrene and 1.87 t o 1 of acetic acid to hydrogen peroxide. Using these optimum mole ratios, Figure 3 depicts the effect of hydrogen peroxide concentration (30 to 90%) on yields of 2,2'diphenic acid. Effective concentrations are in the raiige 50 t o 65 of hydrogen peroxide. Reactions run a t room temperature (22' to 2.5" C.) gave 110 2,2'-diphenic acid after 24 hours. The reaction was incompletp (42%) after 24 hours a t 50" t o 60' C. For reflux temperatures (100" to 110" C.), the yields of 2,2'-diphenic acid werc indcpendent of time within the range 30 t o 120 minutes.
Effect of Ratio of Reactants on Yield
(51). T h e peracetic acid formed is used up as it is formed and the net effect is the ultimate consumption of all the active oxygen present. 2. Alternatively, prepared concentrated peracetic acid solutions.
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DETAILED STUDY O F PERACETIC ACID OXIDATION
Procedure. Essentially the same equipment was used for both the in situ and prepared peracetic acid oxidations. The reactants were placed in a three-necked 1-liter flask which was equipped with ground-glass connections and fitted with a reflux condenser, thermometer, and separatory funnel. The oxidizing agent was added through the latter. An oil or water bath surrounding the flask was employed for regulating the teniperature of the reaction. For both methods, the reaction was carried out using 10-gram samples of technical phenanthrene (90%) (0.0506 mole). For the in situ method, the phenanthrene was added to the glacial acetic acid to which was added a measured quantity of hydrogen peroxide. The resulting paste went into solution with intermittent stirring a t the temperature of incipient reaction. I n the prepared peracetic acid technique, the technical phenanthrene was first dissolved in an inert solvent and then a measured quantity of 40% peracetic acid was added. Almost complete solution was effected and stirring was unnecessary. All reactions were run without the sulfuric acid catalyst. For both methods, the exothermic reaction commenced on warming to 60" to 70" C., whereupon the heating bath was removed. External cooling was momentarily employed if the reaction became too vigorous. The deep red solution was kept a t a slow reflux for a specified length of time. Direct heating was required for only a short time, and after that the exothermic reaction sustained the reflux temperature almost until the end of the reaction This latter point was indicated by a continuous drop in reaction temperature. While still warm, the solution was poured into an equal volume of water. For the in situ process, sufficient 25 yo sodium hydroxide solution was added with vigorous stirring and warming t o p H 8 to 9 (Hydrion paper) to destroy excess peroxide. I n the prepared peracetic acid method, the alkaline solution was added to p H 6 to 7 (water soluble inono-
2118
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REACTION
~~
Oxiden1
-
CONDITIONS 50%
He02
Table I summarizes the effect of various solvents on yields of 2,2'-diphenic acid. No product was formed in the absence of an aliphatic acid or anhydride for peracid formation. More simply, the peracid and not the hydrogen peroxide is the oxidant For maximum yields of a pure product, glacial acetic acid is recommended as the solvent-reactant. Variables of Prepared Peracetic Reaction. Recently availalilca 40% peracetic acid (14) was used throughout the prepared PPIacetic acid oxidation proccdures. Figure 4 illustrates the effect of varying mole ratios of pcracetic
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 45, No. 2
Unit Processes TABLEI. EFFECTO F SOLVENT-REACTANT ON 2,2'-DIPHENIC ACIDYIELD Mole ratios: HaOa t o CirHia 14.0:l Solvent t o Ha&, 1.87:1 Peroxide concentration, 50 70 Reflux temperature, 100-110' C. Reflux time, 1 hour 2,2'-Diphenic Acid Yield, 70 M.p., O C. 34.4 217-220 68-70 228-229
Solvent
Formic acid Acetic acid 58.6 220-226 Propionic acid 49.0 220-222 Acetic anhydride 49.6 200-210 Pronionic anhydride Dioxane ethfl acetate dimethyl formamide None Chlorofo'rrn benzene d r b o n tetrachloride, toluene, cyclohex&e, carbdn disulfidea None Inorganic acid (HCl) b None a All solvents immiscible with 50% hydrogen peroxide u p to reflux temperature. b Much t a r formation.
..... ..... .....
REACTION
CONDITIONS
-
Solvent HOAc R e f l u x Temp. 1oo-llo*c
acid to phenanthrene on yields of 2,2'-diphenic acid. For optimum conditions, a minimum mole ratio of 10 to 1is recommended. This reaction is so vigorously exothermic without a solvent that even external cooling was insufficient to prevent its eruption through the reflux condenser. A study was made, therefore, of various hydrocarbon-water solvents. Table I1 summarizes the results of this investigation. Acetic acid, dioxane, and ethylene. glycol dimethyl ether were found to be satisfactory solvents; the latter two can be recovered and recycled. The use of ethylene glycol dimethyl ether (dimethyl cellosolve), however, gave the whitest and purest form of 2,2'-diphenic acid, SELECTED LABORATORY PROCESS
On the basis of simplicity, product purity and purification, byproduct and solvent recovery, and economics, the laboratory oxidation of phenanthrene with prepared 40 yoperacetic acid was selected for translation to semipilot plant scale. SEMIPILOT PLANT
Raw materials-used were:
-
MOIOI Ratio8
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Figure 3. Effect of Hydrogen Peroxide Concentration on Yield
Water was then cracked into the cooling coil. The latter was in the form of a coiled U-tube made from 7-mm. borosilicate glass tubing. This cooling coil was extremely effective in moderating the reaction rate and preventing the frothing of the reactants when the reaction started. By manually adjusting the cooling water rate, the vigorous reaction was maintained at 90" C. for 1 hour; there was a slight reflux. At the end.of this period, the cooling water was almost shut off, and the solution was permitted to reflux vigorously for 21/2to 3 hours.
Phenanthrene, Reilly's 90% minimum grade (46) Peracetic acid, BECCO's prepared 4oy0solution (14) Ethylene glycol dimethyl ether, Ansul's specialty chemical ( 4 ) Sodium hydroxide, 25 yo solution made from purified flakes Hydrochloric acid, concentrated, technical 20' BB. Operating Procedure. As shown in the flow sheet (Figure 5) 175 grams of technical phenanthrene (90yo,) (0.885 mole), 1342 ml. (8.85 moles) of 4070 peracetic acid, and 1341 ml. (12.9 moles) of ethylene glycol dimethyl ether were added through one of the top openings of a 3-liter, three-necked, interjoint, resin flask, This reaction kettle was equipped with condensers and a n internal cooling coil, and wound with No. 20 Nichrome wire. The Powerstat controlling the reaction kettle temperature was raised until the temperature of the reaction mass reached approximately 70" C.
TABLE 11. EFFECT OF SOLVENT
ON
2,2'-DIPHENIC ACIDYIELD
Mole ratios: CHaCOOOH to Ci4Hia. 10.0 : 1 Solvent t o CHsCOOOH, 1.46:1 Peracetic acid concentration, :O%C Reflux temperature, 100-110 Reflux time, 1 hour Solvent Acetic acid Dioxane Ethylene glycol dimethyl ether Ethylene glycol diethyl ether Diethylene glycol dimethyl ether Diethylene glycol diethyl ether Carbon tetrachloride Cyclohexane Solvent recovered as ether-water
February 1953
2,2'-Diphenic Acid Yield, % M.p., C. 68-71 228-229
68-71 64-08 65 62 60
None None azeotrope.
226-227 228-229
lished. For the in situ laboratory oxidation procedure, it >\asfound that: 1. An aliphatic acid must be present for peracid formation. Acetic acid was the preferred solvent-reactant. 2. A concentration range of 50 to 65% hydrogen peroxide gave lhe best results. Cornmercially available 50% hydrogen peroxide was found to be the most suitable. 3. Optimum mole ratios of hydrogen peroxide to phenanthrene m-ere 14.0 to 1 a n d of acetic acid to hydrogen peroxide, 1.87 t o 1. 4. Reflux temperatures of 100" to 110" C. gave the highest conversions in the shortest time. Using prepared 40% peracetic acid as the laboratory oxidant, i t was determined that: 1. Dioxane and ethylene glycol dimethyl ether were the most suitable solvents. The use of the latter gave an almost colorless product. Both solvent ethers may be recovered by distillation from the mother liquor and recycled. 2. Optimum mole ratios were peracetic acid to phenanthrene, 10.0 to 1, and dimethyl cellosolve to phenanthrene, 1.46 to 1. 3. Reflux temperatures and times were identical to those for the in &tu process.
As a result of these evaluations, the laboratory oxidation of Phenanthrene with prepared 40% peracetic acid was selected for translation to semipilot plant scale. Based entirely on optimum conditions established in the laboratory, a sernipilot plant for batch operation was designed and c'onstructed. It was successfully operated to yield a maximum of '/a pound of 2,2'-diphenic acid per run at an estimated materials cost of $16.00 per pound. This represented a 6770 conversion of phenanthrene. The 2,2'-diphenic acid obtained is of extremely high purity.
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 45, No. 2
-Unit
Processes
ACKNOWLEDGMENT
The authors wish to thank thefollowing for furnishing technical data and samples: Ansul Chemical Co., ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; Reilly Tar and Chemical Corp., phenanthrene; Buffalo Electro-Chemical Co., 50 and 90% hydrogen peroxide and 4Oy0 peracetic acid; and Carbide and Carbon Chemicals Corp., ethylene glycol diethyl ether and diethylene glycol diethyl ether. LlTERATURE CITED
R,
Anschutz, R., and Japp, F. R., Ber., 11, 212 (1878). Anschiitz, R., and Schultz, G., Ann., 196, 37 (1879). Ibid.. p. 50. Ansul Chemical Co., Marinette, Wis., “Specialty Chemicals Bulletin,” p. 4. (5) Atkinson, E. R., Holm-Hansen, D., Nevers, A. D., and Marino, S. A., J . Am. Chem. SOC.,65, 476 (1943). (6) Atkinson, E. R., and Lawler, H. J., “Organic Syntheses,” Coll. Vol. I, 2nd ed., p. 222, New York, John Wiley & Sons, 1946. (7) Atkinson, E. R., Lawler, H . J., Heath, J. C., Kimball, E. H , and Read, E. R., J . Am. Chem. Soc., 63, 730 (1941). (8) Atkinson, E. R., Morgan, C. R., Warren, H. H., and Manning, T. J., Ibid., 67, 1513 (1945). (9) Badisch Anilin- and Soda-Fabrik, German Patent 275,518 (1914); Chem. Zentr.. 1914 11, 279. (10) Barrett Co., and Selden Co., Chem. Zentr., 1921 111, 1318; Selden, J. M., and Seldon Co., British Patent 170,022 (1920); Selden Co., German Patents 88,190 and 90,866 (1921); Chem. Zentr., 1922 11, 574. (11) Benrath, A., and Meyer, A. v., Ber., 45, 2707 (1912). (12) Boeseken, J., and Slooff, G., Rec. k a v . chim., 49,100 (1930). (13) Bogoslovskii, B. M., J . Gen. Chem. (U.S.S.R.), 16, 193 (1946). (14) Buffalo Electro-Chemical Co., Inc., Buffalo, N. Y . , “Peracetic Acid Data Sheet No. 1.” (15) Charrier, G., and Beretta, A,, Gazz. chim. ital., 54, 765 (1924). (16) Ibid., p. 988. (17) Charrier, G., and Moggi, A,, Ibid., 57, 736 (1927). (18) Conant, J. B., and Blatt, A. H., “Chemistry of Organic Compounds,” 3rd ed., p. 557, New York, Macmillan Co., 1949. (19) Cook, J. W., and Schoental, R., J . Chem. SOC., 1950, 47. (20) Eastman Organic Chemicals, Rochester, N. Y., “Catalog and Price, List,” 38th ed., p. 94 (September 1952). (21) Findlay, T. W.,Swern, D., and Scanlan, J. T., J . Am. Chem. Soc., 67, 412. (1945). (22) Fittig, R., and Ostermayer, E., Be?., 5, 933 (1872); Ann., 166, 361, 1365., (1873). (23) Fittig, R., and Schmitz, A., Ann., 193, 116 (1878). (24) Gotz, M., Monatsh. Chem., 23, 27 (1902). (25) Graebe, C., and Aubin, Ch., Ann., 247, 263 (1888). (26) Greenspan, F. P., J . Am. Chem. Sac., 68, 907 (1946). (27) Greenspan, F. P., U. S. Patent 2,490,800 (1949). (28) Henderson, G. G., and Boyd, R., J . Chem. SOC.,97, 1661 (1910). (29) Hilditch, T. P., Ibid., 1828 (1926). (30) Holleman, A. F., Rec. trav. chim., 23, 169 (1904). (31) Huntress, E. H., ”Organic Syntheses,” 7, 30 (1927). (32) Hurtley, W. R. H., J . Chem. SOC.,1929, 1870. (33) Lewis, H. F., and Gibbs, H. D., U. S. Patent 1,288,431 (1919).
@.,c-me-e?3
February 1953
@ea-
Figure 6 .
Semipilot Plant
Linstead, R. P., and Doering, W., J . Am. Chem. Soc., 64, 1991 (1942). Linstead, R. P., and Walpole, A. L., J . Chem. SOC.,1939, 860. Meigs, J. V., U. S. Patent 1,506,297 (1925). Meister Lucius and Brdning, German Patent 152,063 (1904). Meyer, R., and Ppengler, O., Ber., 38, 443 (1905). Milas, N. A , , British Patent 508,526 (1939). Ochiai, E., J. Pharm. SOC. Japan, No. 543, 385 (1927). O’Connor, W. F., and Moriconi, E. J., J . Am. Chem. Soc., 73, 4044 (1951). Oyster, L., and Adkins, H., Ibid., 43, 208 (1921); Bischoff, F., and Adkins, H., Ibid., 45, 1030 (1923). Perkins, W. H., Jr., Proc. Chem. SOC.,23, 166 (1907). Randall, R. B., Benger, M., and Groocock, C. M., Proc. R o y . Soc., A165, 432 (1938). Reilly Tar and Chemical Corp., Indianapolis, Ind., Coal Tar Chemicals Catalog. Roberts, R. C., and Johnson, T. B., J . Am. Chem. SOC.,47,1399 (1925). Scanlan, 3. T., and Swern, D., Ibid., 62, 2305 (1940). Schultz, G., Ann., 196, 21 (1879). Smith, 0. M., Bryant, W. M. D., and Mitchell, J., Jr., J . Am. Chem. SOC.,61, 2407 (1939). Swern, D., Chem. Revs., 45, 1-68 (1949). Swern, D., Billen, G. N., Findlay, T. W., and Scanlan, J. T., J . Am. Chem. SOC.,67, 1786 (1945). Ullman, F., and Meyer, G . M., Ann., 332, 70 (1904). Underwood, H. W., Jr., and Kochmann, E. L., J. Am. Chem. SOC.,46, 2069 (1924). Vorlilnder, D., and Meyer, F., Ann., 320, 138 (1902). Vorozhtov, N. N., and Gurevich, D. A,, J . Applied Chem. (U.S.S.R.),1 8 , 3 (1945). Williams, A. G., U. S. Patent 1,423,980 (1921). Zalkind, Y.S.,and Kaserev, V. V., J . AppEied Chem. (U.S.S.R.), 10,99 (1937). RECEIVED for review September 15, 1982. ACCEPTED November 25, 1952. Based on part of the dissertation submitted by Emil J. Moriconi in partial fulfillment for the Ph.D. degree granted June 1952. Contribution from the Organic Process Laboratory, Fordham University, New York, N. Y.
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