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United S ta tes Pa tent [ 1 9 1 Kuros a ka et a l . [ 1 1 1 4 , 4 3 4 , 3 0 5 [ 4 5 ] F eb . 2 8 , 1 9 8 4 [ 5 4 ] PROCES S F OR PRODUCTION OF HYDROQUINONE [ 7 5 ] Inv entors : Nob no Kuros a ka , Ya m a g uc h i; M a koto Ya s uda , Iw a kuni; Ta da teru M ura ka m i, Ota ke, a l l of J a p a n [ 7 3 ] A s s ig nee: M its ui Petroc h em ic a l s Indus try , L td. , Toky o, J a p a n [ 2 1 ] A p p l . N0 . : 3 2 6 , 2 7 7 [ 5 6 ] Ref eren
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  United States Patent [191 Kurosaka et al. [111 4,434,305 [45] Feb. 28, 1984 [54] PROCESS FOR PRODUCTION OF HYDROQUINONE [75] Inventors: Nobno Kurosaka, Yamaguchi; Makoto Yasuda, Iwakuni; Tadateru Murakami, Otake, all of Japan [73] Assignee: Mitsui Petrochemicals Industry, Ltd., Tokyo, Japan [21] Appl. N0.: 326,277 [56] References Cited U.S. PATENT DOCUMENTS 4,112,244 9/1978 Nowak t al. .................... .. 568/768 4,173,623 l/ 1981 Hashioto et a]. 568/768 4,346,203 1/1981 Wirth ................................ . 568/768 Primary Examiner-Werren B. Lone [57] ABSTRACT High quality hydroquinone is produced from p-diiso propylbenzene dihydroperoxide at a high yield accord ing to the disclosed process. The p-diisopropylbenzene [22] Filed= De¢~ 1’ 1981 dihydroperoxide is decomposed in the presence of an _ _ _ I _ _ acid catalyst and the concentration of the hydroperox [30] Foreign Allpllcatlon Priority Dam ide is maintained in the range of 0.1 to 1% by weight; Dec. 5, 1980 [JP] Japan .............................. .. ss-17os1s the remaining hydroporoxido in the decomposition Stop is further subjected to an acid decomposition prior to [51] Int. Cl.3 ............................................ .. C07C 37/08 the recovery of the formed hydroquinone product [52] US. l. ........................... . 568/768; 568/385 [58] Field of Search .............. .. 568/768, 798, 741, 385 13 Claims, 1 Drawing Figure Alta‘ may} pee-rams 11/:594 . ll miarv? gkga? / .01Pe_. a,‘ aum?a’v m NAT/mil” ‘v’ * + Afr/4. ?nz — ' [V4722 MIBK Mews -'-'—--_P 825%‘? ALBA/ (g0 yr 2.35.‘... ?/srm. r1577‘. 2M7 A»? may’ ‘gag FMM/ 47  4,434,305 \\ Feb. 28, 1984 S. Patent  4,434,305 1 PROCESS FOR PRODUCTION OF HYDROQUINONE BACKGROUND OF THE INVENTION 1. Field of the Invention , p The present invention relates to a process for produc ing hydroquinone having a good color from p-diisop'ro pylbenzene dihydroperoxide (usually referred to here inafter as “p-DHP”) at a high yield. 2. Description of the Prior Art I It has been previously known in the art that hydro quinone is produced by oxidizing, in a liquid phase, p-diisopropylbenzene (usually referred to hereinafter as “p-DIPH”) and/or p-diisopropylbenzene monohydrox yperoxide (usually referred to hereinafter as “p-MHP”) with molecularoxygen from p-DHP, followed by de composition of p-DHP n the presenceof an acid cata lyst. However, in such an oxidation reaction, it is diffi cult to selectively produce only p-DHP. Furthermore, V the separation of high purity p-DHP from the oxidation reaction mixture is a difficult operation and is compli cated, hence expensive, to operate. For these reasons, materials other than p-DI-IP-—including various kinds of by-products, unreacted starting materials, intermedi ate products and the like-—are generally used as starting materials for the acid decomposition. However, when these starting materials are decomposed n the presence of an acid, it is not easy to isolate hydroquinone having a high purity at a commercially acceptable recovery yield. This is because the reaction mixture contains various components other than p-DHP including by products derived from these components as well as by-products derived by p-DHP. For convenience the following abbreviations are used in the following description: p-DHP = -diisopropylbenzene dihydroperoxide p-DIPB p-diisopropylbenzene p-MHP = -diisopropylbenzene monohydroperoxide p-HHP=p-2-hydroxy-2-propyl-a,a-dimethylbenzylhy droperoxide Various attempts have been made to recover hydro quinone having a high purity at a good recovery yield. However, there have been few methods proposed that are convenient to operate and achieve the desired qual ity of the puri?ed hydroquinone as well as the yield of the puri?ed hydroquinone based on p-DHP. Thus, prior to the present invention there are no methods for recov ering hydroquinone which satisfy all the above-men tioned requirements. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart illustrating schematically the operational steps and procedures, including reactants and products, of Example 1. SUMMARY OF THE INVENTION An object of the present invention is to obviate the above-mentioned problems in the art and to provide a process for producing and recovering high quality hy droquinone at a good yield using a p-DHP as a starting material in an acid decomposition reaction in a simple and convenient operation. Other objects and advantages of the present invention will be apparent from the description set forth below. 5 20 25 30 35 50 55 65 2 In accordance with the present invention, a process is provided for producing hydroquinone comprising the steps of: (l) decomposing p-diisopropylbenzene dihy droperoxide in the presence of an acid catalyst; (2) dis tilling the reaction mixture, after removing the acid catalyst therefrom, so that low boiling point compo nents such as acetone, water and the like contained in the reaction mixture are removed from the reaction mixture; and, (3) recovering the thus formed hydroqui none from the distillation residue, characterized in that the decomposition is effected under conditions such that the concentration of the hydroperoxide is main tained within the range of about 0.1 through about 1% by weight and in which the remaining hydroperoxide in the decomposition step is further subjected to an acid decomposition in a distillation column during the re moval of the low boiling point components or in a downstream portion of the distillation column before the recovery of the formed hydroquinone, thus decreas ing the hydroperoxide concentration. DETAILED DESCRIPTION OF THE INVENTION As is well-known in the art, p-DHP s commercially advantageously produced by air oxidizing, in a liquid phase, p-DHP and/or'p-MHP. These oxidation reaction mixtures usually contain, in addition to p-DHP, p-DIPB and p-MI-IP, p-2-hydroxy-2-propyl-a,a-dimethylben zylhydroperoxide (usually referred to hereinafter as “p-HHP”), other alcohols, ole?ns, tar materials and the like. In the practice of the present invention these oxida tion reaction mixtures can themselves be used as a start ing material for the acid decomposition. Alternatively, in order to convert p-HHP contained in these mixtures to p-DHP, the above-mentioned oxidation reaction mixtures can be used after they are further oxidized by an oxidation agent such as hydrogen peroxide. Further more, these types of oxidation reaction mixtures may be used after a portion or all of the unreacted starting materials or by-products are separated and removed therefrom. ‘ In the actual acid decomposition, an organic solvent capable of dissolving hydroquinone and p-DHP can be advantageously used. In view of the post-treatment operation, desirable organic solvents include (1) sol vents which have a boiling point higher than that of water and which are (2) insoluble or only slightly solu ble in water, and preferably (3) are those solvents which are compatible with an aromatic hydrocarbon. Exam ples of suitable organic solvents which satisfy these three requirements are ketones having approximately 6 through 10 carbon atoms, such as, for example, methyl isobutyl ketone, diisopropyl ketones, diisobutyl ketone and the like or, mixtures of these ketones. In addition, other organic solvents such as aromatic hydrocarbons can be used together with the above-mentioned organic solvents, as long as the desired reaction is not adversely affected. The catalysts 'used in the acid decomposition of the present invention include a water-soluble acid such as sulfuric acid, phosphoric acid, perchloric acid and the like, or a solid acid such as silica-alumina, silica magnesia, cation exchange resins and the like. The de sirable catalyst is sulfuric acid,.from the point of view of its low cost and the good selectivity achieved. The content of the hydroperoxide contained in the starting material (including the solvent when a solvent is used) fed to the acid decomposition step is desirably  4,434,305 3 within the range of approximately 40 through 80%, in order to maintain easy control of the reaction and for economy. As used in this description, speci?cation and claims the content (or percentage) of the hydroperoxide is expressed in terms of percent by weight, based on the assumption that, even if the hydroperoxide is used as a mixture of various hydroperoxides, all the hydroperox idesvare p-MHP when the content of the hydroperox- ides are titrated with potassium iodide (the isolated iodine is back titrated with sodium thiosulfate). The amount of the catalyst used in the acid decompo sition largely depends upon the type of catalyst‘ used and the amount of water present in the reaction mixture. As an example, when the water content in the reaction mixture is in the range of 1 through 4% by weight and when sulfuric acid is used as a catalyst, the concentra tion-of the catalyst in the reaction mixture is desirably about 0.1 through about 2% by weight. In the case where a compound such a p-HHP, which can be cov- erted to p-DHP by the action of a peroxide, is contained in the starting material of the acid decomposition, a peroxide such as hydrogen peroxide may be added to the reaction mixture to achieve the desired conversion. The reaction temperature and the period of time required for the acid decomposition reaction are not speci?cally limited, however the acid decomposition is advantageously carried out at a temperature of about 20° C. through about 90° C., more preferably about 50° C. through about 80° C., for a period of time of about 5 to about 60 minutes, more preferably about 15. to about 30 minutes. _ . In the practice of the present invention, it is important to adjust the concentration of the hydroperoxide in the reaction mixture of the acid decomposition to about 0.1 . through about 1% by weight, more preferably about .2- through about 0.5% by weight, by appropriate selection of the above-mentioned reaction conditions. When the acid decomposition reaction is carried out until the concentration of the hydroperoxide in the reaction mix ture falls below the lower limit of the above-mentioned range, not only the total yield of the hydroquinone is decreased, but also the quality of the hydroquinone is adversely affected. On the other hand, when operating under conditions where incomplete acid decomposition occurs, the amount of the remaining hydroperoxide is greater than the upper limit of the above-mentioned range which causes problems in that a dangerous abnor mal reaction is likely’ to occur in the post-treatment operation such as distillation and also that the total yield of the hydroquinone is decreased. Thus, it is virtually necessary to operate the acid decomposition reaction at a hydroquinone concentration within the above-men tioned range. 1 The cid decomposition reaction can be terminated by removal of the acid catalyst. In the case where a water-soluble acid such as sulfuric acid is used, the acid catalyst can be conveniently removed from the reaction mixture by contacting the reaction mixture with an aqueous solution of a neutral salt such as, for example, an aqueous solution of sodium sulfate, potassium sulfate, sodium chloride, sodium phosphate, or ammonium sul fate; preferably an aqueous solution of a sulfate is used. Thus, the water-soluble acid is extracted from the reac tion mixture to the aqueous solution layer. In order to reuse the aqueous solution of the neutral salt, a small amount of a basic compound such as sodium hydroxide can be advantageously added to the aqueous solution of the neutral salt. However, it should be noted that the 25 4 use of an excess amount of the basic compound is not desirablein order to, prevent a change in the properties of the hydroquinone. For this reason, the basic com pound is preferably used in a manner such that, after contacting with the aqueous neutral salt solution, the oil layer containing the hydroquinone is on the acid side, for example, within the pH range of approximately 2 through . The term “pH of the oil layer” as used herein means a pH alue of a water layer determined after the oil layer is thoroughly shaken withan equal volume of water. In the practice of the above-mentioned extraction, in order to‘ decrease the solubility of the hydroquinone in the water ‘layer and to improve the separation of the ‘water layer from the oillayer‘,‘ the use of a highly con centrated aqueous solution of a neutral salt such as, for - example, a concentration of approximately 5'through 30%, by weight, is desirable. Furthermore, in the case Wheré‘hydrdcarbons such’ as aromatic hydrocarbons are contained in the oil'layerf in an amount of approxi mately 3’through 20%,‘by weight, the separation s even further improved. Examples of the aromatic hydrocar bons usedi'for this separation include toluene, xylene, ethylbenzene} cumene, cymene, mesitylene, pseudocu mene,‘ diisopropylbenzene'and the like. Among these hydrocarbons, in the case where a ketone is used as an acid decomposition reaction‘ solvent, a hydrocarbon having-a boiling point higher than that of the ketone is desirably'-'used,taking into account the separation oper ation' in‘v the latterv step. The reaction‘mixture from which the acid catalyst ‘has been‘ removed still contains the reaction solvent, by-products, water and the like, in addition to acetone ‘ and hydroquinone,‘ and- ‘therefore, these components 40 45 50 55 60 65 should be removed from the reaction mixture. In order ‘to remove these components from the reaction mixture, a distillation operation can be carried out ?rst. In the practice of the distillation, a solvent, which has a boiling point higher than that‘ of water and which s insoluble or only slightly soluble in water but is capable of dis solving hydroquinone can advantageously is also pres ent, since the hydroquinone can be obtained in the form of a solution after the removal of acetone and water. When a solvent is used during the acid decomposition reaction, this solvent is inevitably present in the resul tant reaction mixture and, therefore, further addition of solvent is- not necessary. Furthermore, the solvent should be distilled’ off after the removal of acetone, water and the like. In the distillation, in order to prevent decreasing the ‘quality of the hydroquinone and main taining tar or other high boiling point components in a dissolved form, an aromatic hydrocarbon having a boil ing point higher than that of the solvent preferably is also present during the distillation. If such an aromatic hydrocarbon is used‘ in the acid decomposition reaction or in the acid removal operation, further addition of the aromatic hydrocarbon is not necessary. In order to remove acetone and water from the reac tion mixture from which the acid catalyst has been removed, distillation can be carried out by using one distillation column,or by‘using two or more distillation columns acetone is ?rst distilled off and then water is removed ,. .. ~ , In the column bottom liquid from which water has been removed, there is present the remaining hydroper oxide which has not been completelydecomposed dur . ing the acid, decomposition step. The remaining hydro peroxide is further decomposed in the presence of an
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