Method for producing 2,2-bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane

Abstract: Disclosed is a method for producing bis(3-amino-4-hydroxyphenyl) compounds, which comprises reducing bis(3-nitro-4-hydroxyphenyl) compounds with hydrazines in the presence of a catalyst. The method produces bis(3-amino-4-hydroxyphenyl) compounds of high quality under mild conditions at high yields. The products can be isolated and purified in a simple manner to have a higher purity. The method is suitable to industrial-scale production of the products.

Description: FIELD OF THE INVENTION The present invention relates to a method for producing 2,2-bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane. BACKGROUND OF THE INVENTION At present, bis(3-amino-4-hydroxyphenyl) compounds, especially 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane are important as materials for producing heat-resistant polymers, etc. A method mentioned below is known for producing bis(3-amino-4-hydroxyphenyl) compounds, which, however, is problematic in the following points. Japanese Patent Application Laid-Open (JP-A) No. Hei-6-211752 discloses a method of catalytic hydrogenation reduction of bis(3-nitro-4-hydroxyphenyl)hexafluoropropane with a catalyst of palladium-carbon under high-pressure hydrogen. In this method, the purity of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane produced in the reaction mixture is 97 %, and after the catalyst is removed through filtration, the mixture is poured into water for crystallization to obtain a dark gray product. This is recrystallized from a mixture of ethyl acetate and n-hexane to obtain the intended product, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane. In this method, the starting compound is catalytically reduced with high-pressure hydrogen at a high temperature, and the method requires a pressure reactor (e.g., autoclave). Therefore, the method could neither be economical nor advantageous in view of the complicated operations it requires. In addition, the crude product obtained in the method contains coloring components that are difficult to remove, which brings about another problem that the post treatment of the product is not easy. The problems with the conventional method for producing bis(3-amino-4-hydroxyphenyl) compounds noted above are that the method requires severe reaction conditions, expensive equipment and complicated operations, and is therefore neither economical nor simple, that the removal of impurities such as coloring components from the crude product obtained requires specific purification, and that the yield of the product is low. The preparation of 2,2-bis(3-amino-4-hydroxyphenyl) propane from the corresponding dinitro intermediate is described in SU -A- 420 617, the method involves the reduction with hydrazine hydrate over Raney nickel in an aqueous alkaline medium containing isooctyl alcohol as a surface active agent. Hamacher (in Arch. Pharma. 1978; 311:184-195) describes the reduction of bis(3-nitro-4-hydroxyphenyl) compounds by treatment with hydrazine and Raney nickel as catalyst A further reduction is described in SU -A- 1 205 518, bis(3-nitro-4-hydroxy phenoxy) perfluoroarylenes are reduced by hydrazine hydrate in the presence of Raney nickel. Different catalysts are used according to the method of Kubota et al. (J. Pharm. Soc. Japan, 1956; 76: 801 - 804) which deals with the reduction of aromatic nitro compounds using Cu or Fe powder. In EP -A- 0 192 480 the preparation of bis(3-aminophenoxy)-derivatives is described by the reduction of bis(3-nitrophenoxy)-derivatives. SUMMARY OF THE INVENTION We, the present inventors have assiduously studied so as to solve the problems with the conventional method noted above, and, as a result, have found that,'when bis(3-nitro-4-hydroxyphenyl) compounds are reduced with hydrazines in the presence of a catalyst, then bis(3-amino-4-hydroxyphenyl) compounds of high purity are produced under mild reaction conditions at high yields. On the basis of this finding, we have completed the present invention. Specifically, the invention provides the following: (1) A method for producing 2,2-bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane which comprises reducing 2,2-bis(3-nitro-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane with hydrazines in the presence of a platinum and/or palladium catalyst. (2) The method for producing 2,2-bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane according to (1), wherein the reduction is carried out in one or more solvent(s) selected from the group consisting of lower aliphatic alcohols having 1 to 4 carbon atoms, ethylene glycol, propylene glycol, diethylene glycol, cyclic ethers or acyclic ethers. (3) The method for producing 2,2-bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane according to (I) wherein the reaction temperature is between 0 and 120 °C. DETAILED DESCRIPTION OF THE INVENTION Now, the method of the invention is described in detail hereinunder. Hydrazines which are used as a reducing agent in the invention may be any of hydrazine and its derivatives, such as C 1-6 hydrocarbon-substituted hydrazines, and even their salts, so far as they have reducing capabilities. For example, employable are hydrazine, hydrazine monohydrate, lower alkylhydrazines such as methylhydrazine, and also hydrazinium salts such as hydrazinium chloride and hydrazinium sulfate. These reducing agents can be used in the form of their solutions, such as aqueous solutions, alcoholic solutions or etheric solutions. Preferred are aqueous solutions of 60 to 80 wt.% hydrazine monohydrate. Hydrazines are used in an amount of from 2.0 to 20.0 mols, preferably from 2.5 to 10.0 mols, more preferably from 3.0 to 5.0 mols, per mol of bis(3-nitro-4-hydroxyphenyl) compounds. The catalyst for use in the invention is a noble metal catalyst namely a platinum and/or palladium catalyst. The noble metal catalyst for use in the invention includes platinum, and palladium, which may be dispersed on a support such as active charcoal, silica gel, alumina, barium sulfate, calcium carbonate, porous diatomaceous earth, zirconia, magnesium oxide or the like. Especially preferably, it is dispersed on active charcoal and/or alumina and/or silica gel and is carried by them. In one preferred embodiment, from 0.1 to 20.0 % by weight, more preferably from 1.0 to 5.0 % by weight of palladium, based on the support substance, is carried by active charcoal, and the thus-carried palladium catalyst is used. The noble metal may also be used in the form of its oxide, which includes, for example, platinum oxide and palladium oxide. Regarding the ratio by weight of the noble metal catalyst to the starting dinitro-aromatic compound, it is desirable that the amount of the noble metal to be used is from 0.01 to 20.0 % by weight, preferably from 0.01 to 5.0 % by weight, most preferably from 0.05 to 0.5 % by weight, based on the compound 2,2-bis(3-nitro-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane. The catalyst may be a fresh one or a recovered or recycled one. In the method of the invention, the reduction may be effected generally in a solvent. For this, organic solvents may be employed, which include, for example, lower aliphatic alcohols having from 1 to 4 carbon atoms, such as methanol, ethanol, isopropanol, etc.; lower diols such as ethylene glycol, propylene glycol, diethylene glycol, etc.; cyclic ethers such as dioxane, tetrahydrofuran, etc.; acyclic ethers such as ethylene glycol ether, etc.; and mixed solvents comprising any of those organic solvents and water. Especially preferred are methanol, isopropanol and tetrahydrofuran. The amount of the solvent, if used, may be from 0.1 to 20.0 parts by volume, preferably from 0.5 to 5.0 parts by volume, relative to one part by weight of the initial compound. The water content of the mixed solvent comprising the organic solvent and water may be from 1.0 to 99.0 % by volume, preferably from 5.0 to 50.0 % by volume. In the method of the invention, the reaction temperature in the reduction may fall generally between 0 and 120°C, preferably between 10 and 100°C, more preferably between 10 and 90°C, and even more preferably between 40 and 70°C. In the method of the invention, the means of processing the reactants is not specifically limitative. In general, the initial compound 2,2-bis(3-nitro-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane is dissolved in a lower aliphatic alcohol such as methanol or the like, or is directly stirred in dispersion, and thereafter mixed with a predetermined amount of a catalyst. Next, the resulting mixture is kept at a predetermined temperature, to which is gradually and dropwise added a predetermined amount of a hydrazine compound, for example, an aqueous solution of 60 wt.% hydrazine monohydrate. Alternatively, a predetermined amount of a hydrazine compound is first put into a reactor and kept at a predetermined temperature, and 2,2-bis(3-nitro-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane is, after having been dissolved or dispersed in a reaction solvent or while being in powder, continuously or intermittently added to the reactor and is reacted with the hydrazine compound. Though depending on the amount of the catalyst used and the reaction temperature, the reducing agent and 2,2-bis(3-nitro-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane are added to the reactor generally over a period of from 5 minutes to 12 hours. After the reducing agent and 2,2-bis(3-nitro-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane are added, the resulting mixture is, if desired, stirred for further 5 minutes to 48 hours, preferably for further 30 minutes to 12 hours. Where the product formed is sensitive to oxidation, the reaction is preferably effected in an atmosphere of protective vapor, for example, in a nitrogen atmosphere. Where the product is easily colored by oxidation, an antioxidant such as hydrosulfide, sodium sulfide, hydroquinone, methoquinone or the like may be previously added to the reaction system, if desired. The amount of the antioxidant, if added, may be from 0.001 to 0.5 parts by weight, but preferably from 0.01 to 0.1 parts by weight, relative to 1 part by weight of 2,2-bis(3-nitro-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane. After the reaction, the product formed may be isolated from the reaction mixture in any ordinary method that is generally employed for isolating products from reaction mixtures. In general, in the invention, the catalyst used is removed from the reaction mixture through filtration or precipitation, then the reaction mixture is, after having been concentrated or without being concentrated, poured into a bad solvent, or a bad solvent is added to the optionally-concentrated reaction mixture, thereby making crystal precipitated, and the resulting crystal of the intended product is taken out through filtration. Where the reaction mixture is concentrated, it may be from 0.3 to 2.5 times (w/v) or so relative to 1 part by weight of the product, 2,2-bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane formed. Then, a bad solvent may be added to the thus-concentrated reaction mixture which is still hot, thereby making crystal precipitated, and this may be gradually cooled to make the crystal grow therein. The bad solvent may be added to the mixture at room temperature. After having been precipitated, the crystal is collected through filtration. The bad solvent employable herein includes, for example, water and organic hydrocarbon solvents. Examples of the organic hydrocarbon solvents include aromatic hydrocarbons such as toluene, xylene, mesitylene, etc.; and aliphatic hydrocarbons such as n-hexane, cyclohexane, n-heptane, n-octane, etc. Their mixed solvents are also employable. From the reaction mixture from which the catalyst has been removed, the solvent may be evaporated out. In this case, a crude product may be recovered from the concentrate. If desired, the crude product may be purified. For the purification, for example, the concentrate may be subjected to recrystallization using lower aliphatic alcohols having from 1 to 4 carbon atoms (e.g., methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, etc.) or their mixed solvents. For the recrystallization, also employable are lower carboxylates (e.g., methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, etc.), or their mixed solvents. As the lower aliphatic alcohols, preferred are methanol and isopropyl alcohol. More preferred is isopropyl alcohol. As the lower carboxylates, preferred are ethyl acetate and ethyl propionate. More preferred is ethyl acetate. The amount of the solvent of lower aliphatic alcohols or lower carboxylates to be used may be from 0.1 to 50.0 parts by volume, but preferably from 0.1 to 10.0 parts by volume, more preferably from 0.5 to 2.0 parts by volume, relative to 1 part by weight of the product formed. If desired, the product obtained herein may be further purified to have a higher purity, for example, by a method of completely dissolving the products optionally under heat in solvents followed by gradually cooling the resulting solutions for crystallization, a method of putting the products into bad solvents such as those mentioned above to form crystal followed by collecting the crystal through filtration, or a method of stirring and dispersing the crude products in solvents such as those mentioned above followed by filtering the resulting dispersion to collect the purified products. The amount of the lower aliphatic alcohols, the lower carboxylates and their mixed solvents with the organic hydrocarbon solvents or water, if used, may be from 0.5 to 30.0 parts by volume, preferably from 1.0 to 10.0 parts by volume, more preferably from 3.0 to 5.0 parts by volume, relative to 1 part by weight of the crude products, bis(3-amino-4-hydroxyphenyl) compounds. In the mixed solvents, the ratio of the bad solvent of organic hydrocarbons or water is preferably from 5.0 to 95.0 % by volume, more preferably from 10.0 to 60.0 % by volume. If desired, distillation may be employed for the purification. The purity of the product can be easily measured through liquid chromatography. Now, the invention is described in more detail with reference to the following Examples, which, however, are not intended to restrict the scope of the invention. Example 1: 15.0 g of 2,2-bis(3-nitro-4-hydroxyphenyl)hexafluoropropane and 50.0 cc of methanol were put into a 100-cc four-neck flask equipped with a thermometer, a Dimroth condenser and a stirrer, and stirred therein, to which was added 0.23 g (dry weight) of E196R/W5%Pd (trade name, 5 % palladium-carbon catalyst, manufactured by Degussa Japan Co.). This was heated and kept at 60 to 65°C, to which was dropwise added 11.8 g of an aqueous solution of 60 %% hydrazine monohydrate over a period of 20 minutes. If desired, the reaction system was cooled, as generating heat during the reaction. After the aqueous hydrazine solution was added, the mixture was stirred at 70°C for 30 minutes, and then gradually cooled to room temperature. After the catalyst was removed through filtration, methanol and water were evaporated out of the reaction mixture to obtain a crude product of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane. The crude yield was 12.6 g (98 %). The purity in liquid chromatography was 98.3 % (area %). 12.6 g of the crude product, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane obtained above, and 50.0 cc of isopropyl alcohol were put into a 100-cc four-neck flask equipped with a thermometer, a Dimroth condenser and a stirrer, and heated therein until they dissolved in reflux to give a uniform solution. Then, 40 cc of isopropyl alcohol was evaporated out of the solution to make crystal precipitated in the solution. This was stirred under reflux for further 15 minutes, to which was gradually added 30 cc of toluene. This was further stirred still under reflux for additional 15 minutes. Next, this was gradually cooled to room temperature, and stirred for 30 minutes with cooling with ice in water at 0 to 5°C. In that manner, crystal was fully precipitated, and then taken out through filtration. This was fully washed with 50 cc of a cold mixed solution of isopropyl alcohol (10 % by volume) and toluene (90 % by volume), and then fully dried. Thus was obtained white crystal of high purity. The yield in purification was 89.9 %, and the yield of the pure product was 11.6 g. The purity in liquid chromatography was 99.9 % (area %). Example 2: 400.0 g of 2,2-bis(3-nitro-4-hydroxyphenyl)hexafluoropropane and 1200 cc of methanol were put into a 2000-cc four-neck flask equipped with a thermometer, a Dimroth condenser and a stirrer, and stirred therein, to which was added 9.0 g (dry weight) of E196R/W5%Pd. This was heated and kept at 60 to 65°C with stirring, to which was dropwise added 313.2 g of an aqueous solution of 60 % hydrazine monohydrate over a period of 4 hours. After the aqueous hydrazine solution was added, the mixture was stirred for further 30 minutes, and then gradually cooled to room temperature. After the catalyst was removed through filtration, the reaction mixture was concentrated to obtain a crude product of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane. The crude yield was 336.8 g (98 %). The purity in liquid chromatography was 97.9 % (area %). The crude product was purified from a mixed solvent of isopropyl alcohol and toluene in the same manner as in Example 1 to obtain white crystal of high purity. The yield in purification was 89.3 %, and the yield of the pure product was 306.9 g. The purity in liquid chromatography was 99.9 % (area %). Reference Example 1: 100.0 g of 2,2-bis(3-nitro-4-hydroxyphenyl)hexafluoropropane, 300 cc of methanol, and 5.0 g of developed NDT-90 (trade name, Raney nickel catalyst, manufactured by Kawaken Fine Chemical Co.) were put into a 500-cc four-neck flask equipped with a thermometer, a Dimroth condenser and a stirrer, and heated, with stirring, up to 60°C to completely dissolve 2,2-bis(3-nitro-4-hydroxyphenyl)hexafluoropropane in the solvent. The resulting solution was kept at 60 to 65°C, to which was dropwise added 78.3 g of an aqueous solution of 60 % hydrazine monohydrate over a period of 1 hour. After the aqueous hydrazine solution was added, the mixture was stirred for further 30 minutes, and then gradually cooled to room temperature. After the catalyst was removed through filtration, the reaction mixture was concentrated to obtain a crude product of 2,2-bis(3-amino-4-hydroxy- phenyl)hexafluoropropane. The crude yield was 82.5 g (96.0 %). The purity in liquid chromatography was 96.5 % (area %). The crude product was purified from a mixed solvent of isopropyl alcohol and toluene in the same manner as in Example 1 to obtain white crystal of high purity. The yield in purification was 85.5 %, and the yield of the pure product was 73.5 g. The purity in liquid chromatography was 99.9 % (area %). As has been mentioned in detail hereinabove, the method of the invention uses hydrazines as the reducing agent for producing 2,2-bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane from 2,2-bis(3-nitro-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane. The method requires simple operations only, and produces bis(3-amino-4-hydroxyphenyl) compounds of high purity at high yields. The product 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane is especially useful as a starting compound for heat-resistant polymers, especially for those for electronic materials. While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

Claims: A method for producing 2,2-bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane which comprises reducing 2,2-bis(3-nitro-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane with hydrazines in the presence of a platinum and/or palladium catalyst. The method for producing 2,2-bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane according to claim 1, wherein the reduction is carried out in one or more solvent(s) selected from the group consisting of lower aliphatic alcohols having 1 to 4 carbon atoms, ethylene glycol, propylene glycol, diethylene glycol, cyclic ethers or acyclic ethers. The method for producing 2,2-bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane according to claim 1 wherein the reaction temperature is between 0 and 120 °C.

Inventors: FUJIMOTO MASAKI, KUNIKATA KENJI, TOMARU JUN-ICHIRO, FUJIMOTO, MASAKI, KUNIKATA, KENJI, TOMARU, JUN-ICHIRO
Applicants: NIPPON KAYAKU KK, NIPPON KAYAKU KABUSHIKI KAISHA
Application year: 1998
Main classification: C07C213
IPC codes: C07C213, C07C215