Patented Nov. 21, 1950 2,530,369 UNITED STATES PATENT of FICE 2,530,369 OX DATION OF AROMATC COMPOUNDS Joseph H. Simons, State College, Pa., assignor to Phillips Petroleum Company, a corporation of Delaware No Drawing. Application January 29, 1948, Serial No. 5,205. 20 Claims. (C. 260-621) 1. This invention relates to the oxidation of aro Essentially, the process of the present inven matic compounds, and more particularly to a new tion comprises oxidizing an aromatic hydrocar process for the oxidation of aromatic hydrocar bon with an oxidizing agent at temperatures bons whereby phenolic products are formed in ranging from 0 C. to 200° C. in the presence of high yield and substantially all of the carbon liquid hydrogen fluoride. containing products other than phenolic con Very high yields of phenolic compounds are tain the same carbon ring structure as the re obtained to the exclusion of products typical of actant. side chain oxidations which are formed in neg In the past, Several processes have been pro ligible amount when such hydrocarbons as tolu posed for production of aromatic ring substitut O ene, Xylene, methyl naphthalene and the like are ed hydroxy (phenolic) compounds by partial utilized as reactants. Furthermore, the forma Oxidation of aromatic hydrocarbons. Such proc tion of typical ring rupture products, such as ali esses employ a wide variety of methods in which phatic compounds, and gaseous products of rel the oxidations are conducted principally in the atively complete combustion, i. e., carbon diox gaseous phase, with and without catalysts or 5 ide and carbon monoxide are not produced in Contact surfaces. In all Such processes, high substantially all instances. temperatures must be employed i. e., tempera One of the principal advantages of the pres tures greatly in excess of 200° C., as evidenced ent invention resides in the use of liquid hy. by the following United States patents: Bibb drogen fluoride in the reaction medium which No. 1,547,725 (700° C.), Hale No. 1595,299 20 causes ring oxidation to occur in preference to (greater than 300° C.), Bone et al. No. 2,199,585 side chain oxidation. . (200-400° C.), Moyer et al. Nos. 2,223,393 It is believed that the oxidation reaction pro (325-800° C.) and 2,328,920 (650° C.). Further Ceeds as follows: Hydrogen fluoride activates the more, these processes result in the formation of hydrogen on the ring of the aromatic compound undesired by-products such as those produced 2 5 more than on a side chain. The strong dehy by ring rupture, side chain oxidations and rela drating action of the hydrogen fluoride tends to tively complete combustion, for example, ali favor the oxidation. This oxidation in the pres phatic acids, aromatic aldehydes, and particu ence of hydrogen fluoride seems also to be un larly gases such as Carbon dioxide, carbon mon usual in that the oxides of carbon and products oxide. Inflammable gaseous hydrocarbons and 30 which would normally result from the breaking tars are often formed as a result of cracking at of the aromatic ring are not produced. the high temperatures employed. Another distinct advantage flowing from the All such prior art processes are limited in their use of liquid hydrogen fluoride is that the re application to the use of either benzene or ben action will proceed effectively and result in theo Zene and toluene as reactants. In addition, with retical and near theoretical yields of phenolic a single exception (Moyer et al. Nos. 2,223,393 products even at comparatively low tempera and 2,328,920), all of the processes as applied tures within the range above set forth. This to toluene result in oxidation of the alkyl side eliminates the formation of tars and inflammable chain to produce benzyl alcohol, benzaldehyde lower aliphatic hydrocarbon gases commonly and benzoic acid (see Bone et al. 2,199,585) 40 produced by cracking and ring rupture in the rather than formation of cresols. prior art processes where much higher temper Of course, there are many existing processes atures are employed. In fact, the process of the wherein higher homologues of benzene and the like are oxidized to produce products typical of present invention cannot be operated at temper side chain oxidation, such as benzyl alcohol, al atures above 230 C. regardless of the pressure dehydes, and mono and dicarboxylic acids. How of the System since this temperature is the crit ever, such oxidations occur much more readily ical temperature of hydrogen fluoride and the than those involving introduction of an oxy reaction involves the use of hydrogen fluoride group into the nucleus of an aromatic hydro in the liquid phase. carbon. This invention is concerned primarily 50 A further unexpected result characterizing the with the latter type of oxidation. process of this invention is that the so-called According to the present invention, it has been complete combustion products or more properly discovered that aromatic hydrocarbons are ox the end products are a valuable activated carbon idized to predominantly phenolic products in containing the ring structure of the aromatic high yield in the presence of liquid hydrogen 55 hydrocarbon reactant and water. Thus, if the fluoride, and that the carbon-containing by reaction is carried out attemperatures approach products, if any are formed, contain the same ing the maximum for the process, and the re carbon ring structure of the reactant with little action time is prolonged, the hydrocarbon will or no oxidation of side chains if such are eventually be oxidized completely to such acti present, 80 vated carbon and water. The formation of such 8,880,868 3 4. A product as activated carbon in such an oxida uranium, tungsten, manganese, chromium, copa tion process is unusual and striking. per, etc.; selenic acid, arsenic acid, etc. Although It has further been found that the only prod the carrier is frequently added as the element ucts resulting from the process as applied to Or oxide, the fluorides or oxyfluorides are certain non-aromatic compounds are activated carbon ly present in most cases due to the action of and water. This novel method of producing the anhydrous hydrogen fluoride. Because of the activated carbon from non-aromatic compounds oxidizing action of the oxygen or other oxidizing is disclosed and claimed in my copending applica agent present and also due to the reducing action tion Serial No. 424,214, filed December 23, 1941, . of the Organic Substance, the valence of the now U. S. Patent 2,458,107, issued January 4, 1949. 0. oxygen carrier is afforded an opportunity to re The carbon formed is an absorbing or activated versibly change. char which does not require further processing It thus makes little difference in what chemical for activation. As a rule such activated chars form the oxygen carrier is used. For example, cannot be prepared by oxidation of hydrocarbons, the silver may be added either as the metal, the but result from dehydration of carbohydrates. oxide, the fluoride, the bromide, etc., while the In addition to the phenolic compounds, other arsenic may be added as arsenious acid, arsenic products which are in some instances formed acid, or the salts of either of these acids, in the process of the invention include plural arsenious oxide, arsenic oxide, arsenic trichloride, ring systems, such as diphenyl, ditolyl, di and arsenic pentachloride, arsenic trifluoride, arsenic tri naphthyls, di and tri xylyls. 20 pentafluoride, or as any of the oxychlorides, The formation of benzoic acid in the process bromides, fluorides, etc. in some cases where benzene is employed appears Although the addition of an oxygen carrier is to be extremely noteworthy. It is believed that preferred it is not essential for carrying out the this aromatic monocarboxylic acid has never be oxidation process since the oxidation reaction fore been synthesized by oxidation of benzene. will take place in the absence of any added oxygen This formation of benzoic acid was the only in carrier. Because of the extremely wide range stance in which compounds other than those of substances that may be used as oxygen car having the same carbon ring structure as the riers, it is believed, as above stated, that these initial reactants are formed. It is thought that - Substances act as a means of transporting the the hydrogen fluoride activates the hydrogen 30 oxidation properties of the oxygen source to the atoms on the benzene ring to the point of re molecules of the aromatic compound to be moval, which results in the formation of diphenyl oxidized and, therefore, that any substance which between two adjacent benzene molecules. One can reversibly undergo a valence change in the ring of the diphenyl thus formed is ruptured same reaction medium can serve in this capacity. leading to the formation of benzoic acid. The SS For example, silver can both dissolve the oxygen by-products occurring with benzoic acid were not and carry it in the dissolved condition to the identified except that in every case where it aromatic compound, or it can form silver oxide, formed, diphenyl was found to be present. How fluoride or oxyfluoride with the attendant valence ever, it is not intended to limit the invention to change and thus carry the oxidizing property. the foregoing mechanism or any other theory 40 The arsenic compounds, for example, can undergo of action, it being sufficient to state that in some the valence change from the three to the five instances where the yield of phenolic compounds valent forms and vice versa, thus serving as the is not 100%, benzoic acid is formed from benzene. Oxygen carriers. It is a further distinct characteristic of the In some cases mixtures of oxygen carriers may present invention that it is in no way limited to 45 be employed in carrying out the oxidation-reduc the oxidation of benzene to produce phenol, but tion reaction. Without the addition of the car is applicable to aromatic hydrocarbons generally rier to the reaction mixture, the reaction rate is including such compounds as benzene, naphtha slower. All the oxygen carriers act in a similar lene, anthracene, phenanthrene and homologues manner, but there are some minor differences. or alkylated derivatives such as toluene, Xylene, 50 Arsenic and selenium compounds cause the re methylnaphthalene and the like. action to take place at relatively low tempera Oxygen and oxygen-containing gases, such as tures, while molybdenum oxide causes larger air, as well as Solid or liquid oxidizing agents amounts of activated carbon, dimers, and car may be employed in the process for effecting the boxylic acids to be formed at the expense of the Oxidation of the aromatic compound. However, 55 yield of phenolic compounds. air or gaseous oxygen are the preferred oxidizing The reaction takes place either homogeneously agents from practical and economical considera in the liquid phase or heterogeneously between tions. the liquid and solid phases. In the homogeneous It has been found desirable but not essential liquid phase oxygen carriers which are soluble to the practice of this invention to employ an 60 in this phase aid in increasing the rate of the "oxygen carrier.' The term "oxygen carrier' reaction. For the heterogeneous case the larger as contemplated by the invention is used in its the amount of solid surface the faster the rate. accepted sense, namely, an element or compound A large amount of finely divided Solid substance, of an element which in a reaction medium where such as copper, nickel, iron, silver, Monel, carbon, both oxidizing and reducing conditions simul 65 etc., is beneficial. When oxygen, air or other taneously exist will reversibly change its valence. oxygen-containing gas is used as the oxidizing Thus, the particular substance acts as a means agent, the rate of the reaction to a large extent of transporting the oxygen from the available is governed by the rate of Solution of oxygen or source, that is, the oxidizing agent to the re gas into the liquid phase and this depends upon ducing substance, that is, the aromatic hydro 70 the amount of surface between gaseous and liquid carbon to be oxidized. A great variety of Sub phases. Introducing the gas into the liquid in stances have been found suitable for this purpose. the form of small bubbles is beneficial as is also These include finely divided silver, silver oxide, vigorous agitation of the mixture. Another way silver fluoride, etc.; the element or oxides of of providing a large amount of surface is to flow arsenic, selenium, iron, molybdenum, vanadium, 75 the liquid as a film over solid packing in a re 2,580,869 6 action tower where a large amount of surface is wide limits. The oxidation reaction will occur provided exposed to the surrounding gas. Carbon at atmospheric pressure, but becomes inordinately packing is preferred, although any of the above slow at such pressure when low temperatures are mentioned finely divided Solids may be used. employed. The reaction takes place more rapidly The process may be operated either as a batch as the pressure is increased. The rate of reac process or in a cyclic manner. The latter is tion is highly satisfactory when operating at highly preferred insofar as conversions per pass pressures in the range between 500 and 1000 are often quite small. An exemplary method pounds per square inch. However, higher or embodying the cyclic process is conducted as foll lower pressure may be employed, if desired, with lows: A reaction tower consisting of a metallic O satisfactory results. tube or pipe is packed with a finely divided solid Still a third alternative method of practicing Oxygen carrier and provided with external heat the invention comprises the use of a vertical re ing means for obtaining the desired reaction tem action tower packed with a finely divided Sub perature. The tower is then filled with liquid stance which may or may not act as an Oxygen hydrogen fluoride. The aromatic hydrocarbon 5 carrier, for example, iron, copper, nickel, Silver, such as benzene is fed into the reaction column Monel metal or carbon. A mixture of aromatic at the bottom thereof at the desired controlled hydrocarbon and liquid hydrogen fluoride is fed rate. Atmospheric air is also fed into the col to the top of the tower from which it flows slowly umn at the bottom at the desired rate and pres downward while air or oxygen introduced at the sure. Excess air is exhausted at the top of the bottom of the tower flows upward countercur tower, which is provided with a condenser so as rently. A liquid take-off provided at the botton to return liquid substances to the reaction Zone. of the tower is connected to a stripping column Unreacted aromatic hydrocarbon, phenolic and for separating the reaction mixture. The Over other reaction products and hydrogen fluoride head of the stripping column containing unre are discharged from the top of the tower into 25 acted hydrocarbon and hydrogen fluoride is re a stripping still. The overhead of the stripping turned to the tower feed line and the bottoms in still containing unreacted hydrocarbon and hy the stripping column constitute the crude phenolic drogen fluoride is returned to the feed-line of the products. When oxygen rather than air is used, reaction tower, and the bottoms of the still con no exhaust need be provided for gas at the top of stitute the recovered crude phenolic products, the column provided that the oxygen feed rate is and other products, if formed. In many in adjusted to only make up for that used. Further stances the yield of phenolic compound based more, no gaseous products are formed. The tem on the amount of hydrocarbon consumed either erature-pressure conditions are maintained to equaled or approached 100%, that is, the "con insure against vaporization of the hydrogen fluo version efficiency' was extremely high, but the 35 ride and hydrocarbon. conversion per pass based on total hydrocarbon This method of practicing the invention ad present was low. However, by merely recycling vantageously presents an extremely large Con with removal of product formed in each pass near tact surface between the gaseous and liquid re theoretical yields are obtained. actants. Thus, the extremely thin films of liquid An exemplary method for practicing the inven 40 flowing through the interstices of the Solid pack tion as a batch process comprises placing the ing are brought into intimate contact with the aromatic compound in a metal reaction cham surrounding gas. In this procedure, the amount ber, such as an autoclave, with liquid hydrogen of Surface provided causes a Satisfactory rate fluoride and an oxygen carrier. To the reaction of reaction at pressures much lower than the chamber is attached a reflux condenser, the ap 45 Superatmospheric range above stated. In fact, paratus being equipped with appropriate valves even at the lower temperatures, a pressure of the and gauges. The reaction chamber is prefer Order of atmospheric Will give a Satisfactory rate ably placed in a heater on a shaking machine or of reaction. other suitable device for effecting agitation. The molecular ratio of hydrocarbon to hydro When a solid or liquid Oxidizing agent is emir gen fluoride may be varied within extremely wide ployed, it may be added before connecting the limits without affecting the mechanism of the reflux condenser. If a gaseous oxidizing agent reaction to form the desired product. In some Such as air, Oxygen, or other OXygen-containing instances when the ratio exceeds 3 to 1 undesir gas is employed, such gaseous Oxidizing agent may able oxidation begins to occur, such as formation be directly admitted under the desired pressure 55 of the Oxides of Carbon. On the other hand, how to the reaction charmber which is heated to the ever, ratioS as loW aS 1 to 333 produce a conver desired temperature. After the reaction is com sion efficiency of 100%. A mole ratio of 1 to 2 pleted, the excess gases may be exhausted from has also been found to be extremely satisfactory, above the reflux condenser. The hydrogen fluoride and therefore the preferred range is any ratio of and the reaction products are thus retained in 60 3 to 1 or leSS. the Wessel. The reaction products may be sepa The oxidation process can be carried out at rated by distillation, crystallization, or other com temperatures as low as 0°C., but at such tempera monly used method. The hydrogen fluoride emi ture the reaction rate is slow. Room temperatures ployed to effect the reaction may be purified by can be effectively employed particularly when distillation and thus made available for reuse. 65 using a very large amount of contact surface, As stated above, when a gaseous oxidizing agent such as embodied in the third alternative pro Such as air or molecular Oxygen, is employed the cedure utilizing a packed column. reaction rate to a large extent is governed by the The process is governed by a series of rate phe rate of solution of oxygen or gas into the liquid nomena not equilibria. Several reactions are in phase. This depends not only on the amount of Wolved in the process, the first few of which pro Surface between the gaseous and liquid phases, duce the only oxygen-containing products, name but also to some extent on the pressure in the ly, the phenolic compounds and the carboxylic System. When the process is conducted in an compounds such as benzoic acid. Generally, if a autoclave or in a packed pressure column, as completely condensed ring product (activated above described, the pressure can be varied over 75 carbon) is desired high temperatures and longer 9,680,860 7 8 reaction times are employed. The optimum mable gases. The phenol obtained represented a range for high conversion efficiencies for phenolic 77 percent conversion efficiency or yield based products is between 50° C. and 125 C. and this On the amount of benzene Consumed. The re range is therefore preferred. However, lower mainder of the benzene consumed was converted temperatures may be employed although the re to a fine soft carbon. action rate is slower, and temperatures as high as 200° C. may also be employed, although car Eacample 4 bon formation becomes more pronounced at the To 276 parts of toluene were added 100 parts higher temperatures. of hydrogen fluoride and 25 parts of arsenic It is to be noted that when certain diluents, such 10 oxide. Oxygen at 300 pounds per square inch as water, methanol and ethanol are employed, pressure was added, and the vessel was heated the formation of benzoic acid, and dimers and to 100° C. with shaking for two hours. No car trimers of the aromatic hydrocarbon is favored. bon monoxide, carbon dioxide, or inflammable These diluents also tend to necessitate higher re gases were found. 0.1 of a part of benzoic acid action temperatures. Increased formation of 15 and 1.1 parts of Ortho-cresol were obtained. these products was also found to occur when These products represented yields of 6 percent molybdenum compounds were used as the oxygen and 84 percent, respectively, based upon the carrier. amount of toluene consumed. This demonstrates Generally, when employing a gaseous oxidiz that nuclear oxidation occurs in preference to ing agent such as air or molecular oxygen in the 20 side chain oxidation in the presence of liquid autoclave or packed tube embodiments, that is, hydrogen fluoride, The remainder of the toluene the first two of the above-described alternative consumed formed an activated carbon. procedures, it is preferred to operate at pressures between 500 and 1000 pounds per Square inch, at Eacample 5 temperatures between 50° C. and 120° C. It is to 25 To 38 parts of meta-xylene were added 126 be understood that these conditions may be parts of hydrogen fluoride and 32 parts of silver varied. In particular, the pressure employed oxide. Oxygen was added at 1050 pounds per may be of the order of atmospheric when utiliz Square inch. The vessel was shaken at 120 C. ing a large amount of contact Surface. for six hours. No carbon monoxide, Carbon The following examples are illustrative of the dioxide, or inflammable gases were found. 0. process. In the examples the parts referred to part of carbon was produced. 0.2 part of meta are parts by weight, the temperatures are given toluic acid and 0.7 part of 2,4-dimethyl phenol in degrees centigrade, and the pressure is given were obtained. This represents a conversion in pounds per square inch. efficiency of 70% based on m-xylene consumed Eacample it 35 for production of 2,4-dimethylphenol. Eacample 6 To 234 parts of benzene were added 120 parts of hydrogen fluoride and 30 parts of silver oxide. To 115 parts of naphthalene were added 139 The mole ratio of benzene to hydrogen fluoride parts of hydrogen fluoride and 34 parts of iron was 1:2. 900 pounds per Square inch gauge pres 40 Oxide. The Oxygen was added at 1000 pounds per sure of oxygen were added. The furnace was Square inch, and the vessel was heated to 140 C. heated to 65° C. for two hours with shaking. No with shaking for three hours. 0.3 part of beta carbon monoxide, carbon dioxide, or inflam naphthol was obtained. mable gases were found in the products. No carbon was formed. Phenol was the only solid Eacample 7 or liquid organic product other than benzene that A reaction tower was provided consisting of was found in the products. Thus, the 1.3 parts an iron pipe packed with ferric oxide and held of phenol obtained represented approximately a in a vertical position. It was provided with ex 100 percent yield based on the amount of ben ternal electrical heating and maintained at a Zene consumed, that is, 100% conversion eff temperature of 50'. It was initially filled with ciency. liquid hydrogen fluoride. Benzene was fed at Eacample 2 the bottom of the column at the rate of 0.90 liter per hour. Atmospheric air at the rate of 90 cc. To 234 parts of benzene were added 75 parts 5 5 per Second (calculated at standard temperature of hydrogen fluoride and 30 parts of arsenious and pressure) was also fed at the bottom at a oxide. Oxygen was added at 1000 pounds gauge pressure of 500 pounds per square inch. The pressure, and the reaction vessel was shaken and excess air was exhausted at the top of the tower heated to 80° C. for three and One-half hours. through a condenser So as to return liquid Sub No carbon monoxide, carbon dioxide, or inflam 60 stances. Liquid benzene, phenol and hydrogen mable gases were found in the products. No fluoride flowed from the top of the tower into carbon was produced. 1.1 parts of phenol were a stripping still. The overhead of the stripping obtained, and no other organic Substance except still was returned to the feed line of the tower benzene was found. This represents a 100% con and the bottoms of the still were crude phenol. version efficiency. No carbon was produced. About 100% yield and 1% conversion to phenol resulted. Eacample 3 Eacample 8 To 135 parts of benzene were added 70 parts In this example the process of Example 7 was of hydrogen fluoride and 8 parts of selenium 70 varied by using Oxygen gas instead of air and Oxide. Oxygen at 1000 pounds per square inch a tower temperature of 70. The benzene feed pressure was added, and the vessel was heated to rate was increased to two liters per hour and 100° C. for three hours. 1.3 parts of phenol were a faster rate of production of phenol resulted obtained, and there were no detectable amounts with approximately the same yield and conver of carbon monoxide, carbon dioxide, or inflam- 75 son, 2,530,809 ) O The following examples are further illustrative remainder of the benzene consumed was cons of the process of the present invention: verted to a soft finely divided carbon, indicating

Per Cent Initial Final Per Cent Per Cent Yield Example No. BenzeneEi Oxygen Carrier Oxygen Tap, Time,Hous basedPhenol on baseionCarbon Phenol based o Pressure Benene Betiane ene

785 4.0 2.5 0.0 00 785 6.0 10 0.0 00 85 . 2.73 5.5 5

O 0,90 O.0 100 13------12 5Ag, 19ul----- SS s O 0.69 0.0 100 i------f2 5Ag, Cu, IBO------OO SS 3.0 1.050 O.) 100 In Example 11, 85% of the phenol was converted to carbon which indicates that carbon formation is more pronounced with temperatures approaching the maximum and when the reaction time is prolonged. Eacample 15 that this oxygen carrier favors carbon formation, To 78 parts of benzene were added 120 parts as well as benzoic acid. of liquid hydrogen fluoride. This is a mole ratio in another instance using molybdenum oxide of 1:6. No oxygen carrier was added. Oxygen 20 as the oxygen carrier, where a temperature of at 50 pounds per square inch pressure was added 120° C. and a pressure of 1050 pounds per square and the temperature raised to 150° C. with inch were employed with the same proportions agitation for Seven hours. The reaction Wessel of reactants and a reaction time of eight hours, was then cooled and its contents examined. No a small quantity of phenol was formed together carbon monoxide, carbon dioxide, or any in 25 with benzoic acid, and biphenyl. The greater flammable gas was found. One-fifth of a part proportion of phenol was converted to carbon. of phenol was obtained, which represented a Eacample 20 yield of 28 percent based on the amount of ben To 234 parts of benzene were added 128 parts Zene consumed. The remainder of the benzene of hydrogen fluoride, 30 parts of arsenic oxide, consumed was converted to carbon. This run 30 and 18 parts of water. Oxygen was added at again indicates carbon formation is favored at 1000 pounds per square inch, and for four hours the higher temperatures and prolonged reaction the vessel was shaken at 100 C. No carbon time. Eacample 16 monoxide, carbon dioxide, or inflammable gases 35 were obtained, 0.1 of a part of phenol and 0.2 To 234 parts of benzene were added 160 parts of a part of biphenyl were obtained, representing of hydrogen fluoride and 30 parts of silver oxide. 21% phenol and 25% biphenyl based on the The mole ratio of hydrocarbon to hydrogen fluo benzene consumed. ride was 1:2.6. Oxygen was added at 700 pounds Eacample 21 per square inch and held at this pressure for 40 two hours with shaking at room temperature To 234 parts of benzene were added 135 parts (25 C.). No carbon monoxide, carbon dioxide, of hydrogen fluoride, 30 parts of arsenic oxide, or inflammable gases were detected after re and 64 parts of methanol. Oxygen was admitted action. A small amount of phenol was obtained. at 1000 pounds per square inch pressure. The vessel was shaken for Seven hours at 120° C. No Eacample 17 45 carbon monoxide, carbon dioxide, or inflammable To 234 parts of benzene were added 120 parts gases were obtained. 0.2 of a part of phenol of hydrogen fluoride and 200 parts of silver oxide. and 0.1 of a part of biphenyl were obtained. A This mixture was heated for four hours at 80 conversion efficiency of 51% as to phenol and C. with agitation. In the products were found 16% as to biphenyl is represented by these 1.5 parts of phenol, which represented the only 50 results. organic substance other than benzene. Carbon Eacample 22 containing gases were not found. To 234 parts of benzene were added 128 parts Encample 18 of hydrogen fluoride, 30 parts of arsenic trioxide and 36 parts of water. Oxygen was added at To 234 parts of benzene were added 120 parts 55 1400 pounds per square inch and for eight hours of hydrogen fluoride and 35 parts offinely divided the vessel was shaken at 200° C. No carbon ox silver. Oxygen at 1000 pounds gauge pressure ides or inflammable gases were obtained. A con was added and the reaction vesse heated to 85 version efficiency of 6% phenol, 17% benzoic C. for three hours with shaking. From the re acid, and 4% biphenyl was obtained, the re action mixture 1.2 parts of phenol were obtained O mainder of benzene consumed forming carbon. and no other organic Substance was present ex Examples 20 to 22, inclusive, indicate the ef cept unreacted benzene, fect of water and methanol as diluents which Eacdmple 19 favor formation of benzoic acid and biphenyl. To 234 parts of benzene were added 120 parts 65 The 200° C. temperature of Example 22 definitely of hydrogen fluoride and 32 parts of molyb favored carbon formation although 6% phenol denum oxide. Oxygen was added at 1000 pounds was formed. per Square inch pressure, and the vessel was Eacample 23 heated at 100° C. with shaking for three and To 234 parts of benzene were added 120 parts One-half hours. No carbon monoxide, carbon 70 of hydrogen fluoride. No additional oxygen car dioxide, or inflammable gases were found. 0.8 rier was added. Oxygen was added at 850 pounds of a part of biphenyl and also 0.3 of a part of per square inch pressure. The vessel was heated benzoic acid were obtained. These represented to 130 C, with shaking for one hour. 2.7 parts 10 per cent and 5 per cent yields, respectively, of benzoic acid and 0.8 part of phenol were ob based on the amount of benzene consumed. The 75 tained. 2,580,869 11 2 Eacample 24 taining liquid hydrogen fluoride for a time lim 156 parts of benzene and 300 parts of hydrogen ited to produce said products, while maintaining fluoride were placed in a copper vessel equipped the molecular ratio of the said aromatic hydro with a reflux condenser. With the vessel at room carbon to liquid hydrogen fluoride not in excess temperature, oxygen was bubbled through the of 3 to 1. liquid mixture at atmospheric pressure at a rate 10. A process according to claim 9 in which of 12 liters per hour for five hours. A trace of the oxidation is conducted in a reaction medium phenol was obtained. having as an oxygen carrier a compound of an The foregoing examples are illustrative of the element capable of changing its state of oxida broad application of the invention to the prepara O tion reversibly under oxidizing conditions. tion of aromatic hydroxy and aromatic carboxy 11. A process according to claim 9 in which compounds and other oxidation products con phenol is formed by oxidizing benzene at a tem taining the same carbon ring structure as the re perature between 50 and 125° C. actant which do not contain Oxygen, such as con 12. A process according to claim 11 in which densed ring derivatives and activated carbon by 5 the oxidation is effected by an oxygen-contain oxidation in the presence of liquid hydrogen ing gas at pressures between 500 and 1000 pounds fluoride. It is to be understood that the specific per square inch. reaction conditions will vary, depending upon 13. A process of producing mono hydroxy nu the particular material being oxidized and the clear substituted aromatic compounds which com product desired. 20 prises oxidizing an aromatic hydrocarbon se The present application is in part a continua lected from the group consisting of benzene, tion of my copending application No. 424,215, naphthalene, anthracene, phenanthrene, and ho filed December 23, 1941, and now abandoned. mologues thereof under superatmospheric pres The foregoing description is given by way of sure at a temperature between 0 and 200° C. in exemplification of the invention and is not to 25 a reaction mixture containing liquid hydrogen be construed in limitation thereof, the invention fluoride and as an oxygen carrier a compound of being limited only by the scope of the subjoined an element capable of changing its state of oxi claim.S. - dation reversibly under oxidizing conditions, Having thus described my invention, I claim: maintaining the mole ratio of hydrocarbon to 1. A process of Oxidizing aromatic hydrocar 30 hydrogen fluoride not in excess of 3 to 1, and re bons Selected from the group consisting of ben covering the hydroxy aromatic compound thus zene, naphthalene, anthracene, phenanthrene, formed. and homologues thereof to produce phenolic com 14. A process according to claim 13 in which pounds which comprises oxidizing an aromatic the oxidation is effected by an oxygen-contain hydrocarbon selected from the group consisting of 35 ing gaS. benzene, naphthalene, anthracene, phenanthrene, 15. A process according to claim 13 in which and homologues thereof under superatmospheric the hydroxy aromatic compound is ortho-cresol pressure at a temperature between 0 and 230° C. and the aromatic hydrocarbon is toluene. for a time limited to produce said phenolic com 16. A process according to claim 13 in which pounds, in a reaction mixture containing suf 40 the hydroxy aromatic compound is 2,4 dimethyl ficient liquid hydrogen fluoride to minimize pro phenol and the aromatic hydrocarbon is meta duction of oxides of carbon and inflammable Xylene. gases. 17. A process of oxidizing benzene to phenol 2. A process according to claim 1 in which which comprises oxidizing the benzene under phenol is formed by oxidizing benzene. Superatmospheric pressure at a temperature be 3. A process according to claim 1 in which the tween 0 and 200° C. in a reaction medium con oxidation is conducted in a reaction medium hav taining liquid hydrogen fluoride, while maintain ing as an oxygen carrier a compound of an ele ing the molecular ratio of the benzene to hydro ment capable of changing its state of oxidation gen fluoride not in excess of 3 to i, said reaction reversibly under oxidizing conditions. medium having as an oxygen carrier a compound 4. A process according to claim 3 in which said of an element capable of changing its state of oxygen carrier comprises silver as said element. oxidation reversibly under oxidizing conditions. 5. A process according to claim 3 in which said 18. A process according to claim 17 in which oxygen carrier comprises iron as said element. the oxidation is effected by gaseous oxygen. 6. A process according to claim 3 in which said 19. A process of oxidizing benzene to phenol oxygen carrier comprises copper as said element. which comprises oxidizing the benzene under 7. A process according to claim 3 in which said superatmospheric pressure at a temperature be oxygen carrier comprises arsenic as said element. tween 0° and 200 C. in a reaction mixture con 8. A process according to claim 3 in which said taining liquid hydrogen fluoride, while maintain oxygen carrier comprises selenium as said ele 60 ing the molecular ratio of the benzene to liquid ment. hydrogen fluoride within the range of 1:6 to 3:1, 9. A process of oxidizing aromatic hydrocar the reaction medium having as an oxygen car bons selected from the group consisting of ben rier a compound of an element capable of chang Zene, naphthalene, anthracene, phenanthrene, ing its state of Oxidation reversibly under oxidiz and homologues thereof to produce products com 65 ing conditions. prising at least a major proportion of phenolic 20. A process according to claim 7 in which compounds and not more than minor propor the pxidation is effected by gaseous oxygen. tions of carbon-containing products retaining JOSEPH. H. SMONS. the carbon ring structure of the reactant and REFERENCES CTE) containing no oxygen, which comprises oxidizing O The following references are of record in the an aromatic hydrocarbon selected from the group file of this patent: consisting of benzene, naphthalene, anthracene, phenanthrene, and homologues thereof under UNITED STATES PATENTS superatmospheric pressure at a temperature be Number Name Date tween 0 and 200° C. in a reaction mixture cons 75 2,367,731 Moyer et al. ------Jan. 23, 1945 l3 W l

Certificate of Correction Patent No. 2,530,369 November 21, 1950 JOSEPH II. SIMONS - , I It is hereby certified that error appears in the printed specification of the above. numbered patent requiring correction as follows: Column 12, line 66, for the claim reference numeral “7” read 19; and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Office. Signed and sealed this 1st day of May, A. D. 1951.

(sEAL) THOMAS F. MURPHY, Assistant Commissioner of Patents.