United States Patent (19) 11) 4,379,092 Devic 45) Apr. 5, 1983 2,401,225 5/1946 Caesar et al. ................... 260/384 X 54 PROCESS FOR THE PREPARATION OF ANTHRAQUINONE AND ITS SUBSTITUTED 2,842,562 7/1958 Bloom et al......................... 260/369 DERVATIVES 2,871,244 l/1959 Kamlet ................................ 260/369 2,967,187 1/1961 Serres et al. .................... 260/384 X 75 Inventor: Michel Devic, Lyons, France 73) Assignee: PC UK Produits Chimiques Ugine FOREIGN PATENT DOCUMENTS 634987 8/1936 Fed. Rep. of Germany ...... 260/369 Kuhlmann, Courbevoie, France 2031430 2/1972 Fed. Rep. of Germany ...... 260/369 (21) Appl. No.: 324,520 2262007 9/1975 France ................................ 260/369 22 Filed: Nov. 24, 1981 2307786 11/1976 France ................................ 260/369 Primary Examiner-Paul F. Shaver (30) Foreign Application Priority Data Attorney, Agent, or Firm-Beveridge, DeGrandi & Dec. 16, 1980 FR) France ................................ 80 26637 Kline 51) Int. Cl. ......................... C07C 50/18; C09B 1/00 57 ABSTRACT 52 U.S. Cl. ..................................... 260/369; 260/384 58) Field of Search ................................ 260/369,384 A process for the preparation of anthraquinone com pounds by condensation of phthalic anhydride with a 56 References Cited benzene derivative wherein a mixture of hydrofluoric U.S. PATENT DOCUMENTS acid and boron trifluoride is utilized as catalyst. l,515,325 11/1924 Bailey .................................. 260/369 2,174,118 9/1939 Calcott et al. ...................... 260/35 7 Claims, No Drawings 4,379,092 1. 2 molecular mixture of HF and BF3 does not cause cycli PROCESS FOR THE PREPARATION OF zation is quite unexpected since the cyclization of benz ANTHRAQUINONE AND ITS SUBSTITUTED oyl-benzoic acid takes place in anhydrous HF (U.S. Pat. DERVATIVES No. 2,174,118). The present invention therefore relates to a process The invention relates to a new process for the prepa for the preparation of compounds of general formula (I) ration of anthraquinone and its substituted derivatives which comprises reacting phthalic anhydride which of the general formula: can be substituted of the formula: O R3 R (I) R3 (II) O 15 R4 R2 R4 in which R, R2, R3 and R4 each represent a hydrogen or halogen atom or a linear or branched alkyl group with a benzene compound of the general formula: containing 1 to 5 carbon atoms. These compounds are 20 used for dyestuffs, paper pulp industries and for the R (III) manufacture of hydrogen peroxide. It is known that anthraquinone is produced industri ally by oxidation of anthracene (BIOS 1148). This pro cess, however, is dependent upon problems of supply of anthracene from coal tar. It has been proposed to pre 25 pare anthraquinone from 1,4-naphthoguinone and buta R2 diene (British Pat. No. 895,620) but the processes for obtaining 1,4-naphthoguinone are complicated and in which R, R2, R3 and R4 have the same definitions as costly (DOS 2,532,365 which corresponds to British above in the presence of a catalyst, characterized in that Pat. No. 1,499,068). 30 the latter consists of a mixture of hydrofluoric acid and Another much used industrial method enables anthra boron trifluoride and that the o-benzoyl benzoic acid quinone and the substituted anthraquinones to be pre thus obtained of the general formula: pared from phthalic anhydride and benzene in the pres ence of aluminum chloride (U.S. Pat. No. 1,656,575), R3 O R (IV) but this method has the disadvantage of the very consid 35 erable cost of the aluminum chloride which is consumed at the rate of 2 moles of aluminum chloride per mole of phthalic anhydride. In order to alleviate this disadvan tage it has been proposed to react the gaseous mixture at COOH high temperature over a solid catalyst based on a silico 40 R4 R2 aluminate (Japan Kokai Sho 49/30350 and Sho 49/95952) or else based on titanium oxide (Japan Kokai in which R1, R2, R3 and R4 have the same definitions as Sho 54/70252) but these processes impose the operation above, is converted into a compound of formula (I) in the gaseous phase at high temperature and necessitate according to the process known per se. a complex installation with a costly investment. 45 The amount of BF3 must be greater than 3 moles per The object of the present invention is to provide a mole of phthalic anhydride; the preferred ratio is be catalyst which enables the condensation of phthalic tween 5 and 20 moles of BF3 per mole of phthalic anhy anhydride and benzene to be effected at low tempera dride. The amount of HF must be greater than 2 moles ture and in the liquid phase as when using aluminum per mole of phthalic anhydride. The preferred ratio is chloride, but having the advantage of being able to be 50 between 5 and 15 moles. The molar ratio HF to BF3 recovered after the reaction. It has already been shown (Russian Pat. No. 189,445) must be near to 1, when the amount of catalyst is lower that hydrofluoric acid catalyzes the condensation of than 15 (moles of HF--moles of BF3 <15). The pre phthalic anhydride with phenols. This reaction, how ferred ratio is between 0.6 and 1.5. For amounts of BF3 ever, takes place only with highly active benzene deriv 55 greater than 10 moles per mole of phthalic anhydride, atives owing to the phenol function and no condensa the preferred ratio is between 0.2 and 1. tion is produced with benzene, chlorobenzene and the Since the catalyst also takes the place of a solvent for alkylbenzenes. Boron trifluoride does not exhibit suffi the reaction, it must be used in sufficient quantity to cient catalytic activity to condense benzene with make the reaction mass fluid, for example, from 5 to 20 phthalic anhydride. W 60 moles of BF3 per mole of phthalic anhydride. This It has now been discovered, according to the present amount may be reduced by the use of a third solvent invention, that an equimolecular mixture of HF and which is inert under the conditions of the reaction. As BF3 catalyzes the condensation of phthalic anhydride inert solvents methylene chloride and liquid CO2 may and benzene and does this, rather surprisingly, without be mentioned. causing cyclization of the benzoylbenzoic acid formed, 65 The phthalic anhydride and the aromatic derivative therefore without liberating a molecule of water which of formula (III) are employed at the rate of 0.9 to 1.2 would hydrolyze or hydrate BF3 and thus make the moles of compound (III) per mole of phthalic anhy recovery of the catalyst difficult. The fact that the equi dride. In order to reduce the formation of by-products, 4,379,092 3 4. it is preferred to use 1 to 1.1 mole of benzene compound purification by extraction with 600cm3 of boiling water, per mole of phthalic anhudrice. Excess of benzenic then crystallization by cooling to 20 C., o-benzoyl compound favors the formation of the phenyl-phthalic benzoic acid titrating 98.4% was obtained. derivatives of the general formulas: 5g of the purified benzoyl benzoic acid were heated R1 R R R2 R2 R2 R3 R3 R2 I COOH R4 O R4 R; The reaction may be effected at temperatures from - 60° C., to +30 C., the preferred temperature being at 100° C. for 2 hours in 50 g of fuming sulfuric acid from - 40 C. to 0° C. A temperature over 30° C. in (20% SO3). The mixture was run on 350 cm3 of water creases the quantity of by-products of the phenyl-phtha and ice and the precipitate obtained was filtered, lide type. The length of reaction is between 5 and 60 25 washed and dried. 4.2 g of anthraquinone were ob minutes according to the temperature. The reaction tained. takes place under a pressure of 5 to 60 bars according to the temperature. EXAMPLE 2 (Comparative) At the end of the reaction the greater part of catalyst The procedure was as in Example 1, but with 7.4 g of is recovered by distillation under reduced pressure. The 30 phthalic anhydride, 39 g of benzene, 8.5g of BF3 and no pure o-benzoyl benzoic acid is obtained by extraction of HF. The mixture was maintained at 60° C. for 4 hours the crude mixture with boiling water, followed by re under 22 bars pressure. After evaporation in vacuo of crystallization by cooling. The impurities from the reac the catalyst, the residue was washed with cold water tion form a phase immiscible with water and can be and then dried. 5.6 g of product were obtained consist eliminated by decantation or by filtration on an absor 35 ing essentially of phthalic acid. bent support. The pure o-benzoyl benzoic acid can be obtained by EXAMPLE 3 (Comparative) treating the reaction medium, after evaporation of the The procedure was as in Example 1, but with 7.4 g of catalyst under vacuum, by means of a sodium hydroxide phthalic anhydride, 39 g of benzene, 10 g of HF and no solution and adding an inorganic acid to reprecipitate 40 BF3. The mixture was maintained at 100° C. for 4 hours the acid. under 5 bars pressure. After evaporation in vacuo of the The o-benzoyl benzoic acid of general formula (IV) catalyst, the residue was washed with cold water, then can be converted into the anthraquinone of general dried. 7.01 g of product were obtained consisting essen formula (I) by heating in concentrated sulfuric acid or tially of phthalic acid. by any other means of cyclization known in the art.