PROCESS FOR PREPARING FLUORINE-SUBSTITUTED ALICYCLIC DIOLS

Abstract: A process for preparing a fluorine-substituted alicyclic diol comprising hydrogenating in the presence of a catalyst a fluorine-substituted aromatic diol represented by formula (I): wherein Ph represents a divalent organic group containing at least one aromatic group, to obtain the fluorine-­ substituted alicyclic diol represented by formula (II): wherein Ph(H) represents a divalent organic group containing at least one perhydroaromatic group.

Description: The present invention relates to a process for preparing a fluorine-substituted alicyclic diol. The diol is used as a starting material for epoxy resins, polyurethane resins, polyester resins, or the like which are excellent in heat resistance, water resistance, tracking resistance, weather resistance, and the like. These resins are used as adhesives, vehicles of paints, packing materials for electronic devices, etc. BACKGROUND OF THE INVENTION It is disclosed that bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexane, a representative example of fluorine-substituted alicyclic diols, is prepared by a process in which hexafluoroacetone is free-radically added to cyclohexane in J. Am. Chem. Soc. , vol. 89. pages 1422 to 1430 (1967). However, by the process, the period of time required for completing the reaction is considerably long, and the yield is low, because by-products such as cyclohexyl-1,1,1,3,3,3-hexafluoroisopropyl ether, 1,1,1,3,3,3-hexafluoro-2-cyclohexyl-2-propanol and the like generate in a large amount. CA 102 (23) 569 (1985), 203 622 F discloses the hydrogenation of 4-(2-hydroxyperfluoropropyl)-phenol in acetic acid over platinum oxide as the catalyst to produce the corresponding cyclohexanol derivative with a yield of 27%. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a novel process for preparing a fluorine-substituted alicyclic diol. Another object of the present invention is to provide a process for preparing a fluorine-substituted alicyclic diol by which the fluorine-substituted alicyclic diol can be obtained in a short period of time and a high yield, and with a small amount of by-products. Other objects of the present invention will be apparent from the following description. It has been found that the above objects of the present invention can be achieved by a process for preparing a fluorine-substituted alicyclic diol comprising hydrogenating a fluorine-substituted aromatic diol represented by formula (I): wherein Ph represents a divalent organic group selected from the group consisting of a phenylene group, a biphenylene group, a terphenylene group, a phenyleneoxyphenylene group, a phenylenethiophenylene group, a phenylenealkylenephenylene group, an anthrylene group, a phenanthrylene group and said divalent organic group of which at least one hydrogen atom is substituted by a methyl group, a hydroxyl group, an amino group or a halogen atom, the alkylene group contained in said group represented by Ph having from 1 to 10 carbon atoms, in the presence of a rhodium catalyst in an amount of from 0.001 to 20 wt% based on the amount of said fluorine-substituted aromatic diol; to obtain the fluorine-substituted alicyclic diol represented by formula (II): wherein Ph(H) represents the corresponding perhydro-Ph group. DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in more detail below. Examples of the halogen atom as the substituent for at least one hydrogen atom in the divalent organic group are a chlorine atom and a fluorine atom. The alkylene group contained in the above mentioned divalent organic groups has from 1 to 10 carbon atoms. Examples of the divalent organic group represented by Ph(H) include a perhydrophenylene group, a perhydrobiphenylene group, a perhydroterphenylene group, a perhydrophenyleneoxyphenylene group, a perhydrophenylenethiophenylene group, a perhydrophenylenealkylenephenylene group, a perhydroperhydroanthrylene group, and a perhydrophenanthrylene group, a hydrogen atom of which may be substituted by a methyl group, a hydroxyl group, an amino group, or a halogen atom such as a chlorine atom and a fluorine atom. The alkylene group contained in the above groups has from 1 to 10 carbon atoms. Specific examples of the aromatic diol represented by formula (I) include the following compounds, but the present invention is not intended to be limited thereto. In the above compounds, X represents an oxygen atom, a sulfur atom, or an alkylene group having from 1 to 10 carbon atoms. These aromatic diols represented by formula (I) can be prepared by any known method, e.g., by addition reaction of hexafluoroacetone to an aromatic hydrocarbon, such as benzene, naphthalene, biphenyl, etc., at 40 to 50°C in the presence of anhydrous aluminum chloride, as described in J. Org. Chem. , vol. 30, pages 998 to 1001 (1965). The group may be connected to any position of the aromatic nuclei, and other hydrogen atoms in the aromatic nuclei may further be substituted by a methyl group, a hydroxyl group, an amino group, a halogen atom, such as a chlorine atom and a fluorine atom in addition to the above-mentioned fluorine-containing group. By the hydrogenating reaction according to the present invention, the following compounds can also be hydrogenated as well as the aromatic diol represented by formula (I). The rhodium catalyst is used in the form of an oxide as well as the metal. The catalyst is generally supported on a carrier in an amount of from 0.01 to 30 wt% based on the total amount of the catalyst and the carrier. Examples of the carrier include activated carbon, alumina and zeolite. The reaction in the process according to the present invention is generally carried out at a temperature from 10 to 250°C, and preferably from 50 to 200°C; and it does not depend on the hydrogen pressure and is carried out generally under a hydrogen pressure of from 0.1 to 24.5 MPa·G (1 to 250 kg/cm²G), and preferably from 9.8 to 14.7 MPa·G (10 to 150 kg/cm²G). A solvent can be used in the process according to the present invention. Alcohols are generally used as the solvent. Preferred examples of the solvent include methanol, ethanol, n-propanol, isopropanol, n-butanol, etc. The solvent is preferably used in an amount of from the same weight as the weight of the aromatic diol to 30 times the weight of the aromatic diol. After completion of the hydrogenating reaction, the objective compound (i.e., a fluorine-substituted alicyclic diol) can be isolated by filtering off the catalyst and then applying conventional isolation techniques such as distillation, recrystallization, or column chromatography. By the hydrogenating reaction according to the present invention, a fluorine-substituted alicyclic diol represented by formula (II) is obtained: wherein Ph(H) represents the corresponding perhydr-Ph group. Specific examples of the alicyclic diol represented by formula (II) include the following compounds, but the present invention is not intended to be limited thereto. In the above compounds, X represents an oxygen atom, a sulfur atom, or an alkylene group having from 1 to 10 carbon atoms. The group may be connected to any position of the perhydroaromatic nuclei, and other hydrogen atoms in the perhydroaromatic nuclei may further be substituted by a methyl group, a hydroxyl group, an amino group, a halogen atom, such as a chlorine atom and a fluorine atom in addition to the above-mentioned fluorine-containing group. By the hydrogenating reaction according to the present invention, the following compounds can also be prepared as well as the alicyclic diol represented by formula (II). The present invention will be explained in more detail below by referring to examples, but the present invention is not intended to be limited thereto. Unless indicated specifically, all ratios, percents, or the like are by weight. EXAMPLE 1 Preparation of bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)benzene 117 g (1.5 mol) of benzene and 31 g (0.23 mol) of anhydrous aluminum chloride were placed in a 1ℓ-flask equipped with a stirrer, and 500 g (3 mol) of hexafluoroacetone was added thereto in an addition rate of about 5 g/minute at room temperature. After the completion of the addition, the reaction mixture was distilled under reduced pressure to obtain 517 g (1.26 mol) of bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)benzene having a meta-isomer/para-isomer ratio of 85/15 [b.p.: 102-106°C/2.6 kPa (20mmHg)]. The yield based on the starting hexafluoroacetone was 84%. Preparation of bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexane A mixture of 300 g (0.73 mol) of the above-prepared bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)benzene and 300 ml of isopropanol was placed in an autoclave made of Hastelloy (trademark of a heat resistant nickel alloy made by Haynes Stellite Co.), and then 30 g of activated carbon carrying catalyst of rhodium in an amount of 5 wt% based on the total amount of the catalyst and the activated carbon was added thereto. The mixture was heated to 155°C while stirring, and then hydrogen was blown into the mixture at the substantially same temperature under a hydrogen pressure of 5.9 MPa·G (60 kg/cm²G) for 4.5 hours. After the completion of the reaction, the reaction mixture was cooled to room temperature. Then, the catalyst was filterred off, and the filtrate was distilled to remove the isopropanol and to obtain 287 g (0.69 mol) of bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexane [b.p.: 96-100°C/0.79 kPa (6 mmHg)]. The yield based on the amount of bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)benzene was 94%. Results of ¹H-NMR (nuclear magnetic resonance) (solvent: carbon tetrachloride) analysis were as follows: δ (ppm) = 3.1 (2H, s, OH), 1.1-2.5 (10H, br, CH or CH₂) EXAMPLE 2 The same procedures as in Example 1 were repeated except that the amount of activated carbon carrying the catalyst was changed to 15 g, the reaction temperature was changed to 160°C, and the reaction time was changed to 9 hours. As a result, 282 g of bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexane was obtained. COMPARATIVE EXAMPLES 1 TO 3 The same procedures as in Example 1 were repeated except that the rhodium as the catalyst was changed to ruthenium (COMPARATIVE Example 1), palladium (COMPARATIVE Example 2), and platimun (COMPARATIVE Example 3) to obtain bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexane. The yields in COMPARATIVE Examples 1 to 3 were 29 g (9.5%), 44 g (14%), and 85 g (28%), respectively. COMPARATIVE EXAMPLE 4 63 g (0.75 mol) of cyclohexane, 246 g (1.48 mol) of hexafluoroacetone, and 1.46 g (0.01 mol) of di-tert-butylperoxide were placed in an autoclave made of Hastelloy, and the mixture was stirred for 8 hours at 135°C. After cooling, 1.46 g (0.01 mol) of di-tert-butylperoxide was added thereto while applying pressure, and the mixture was stirred for 8 hours at 135°C. The procedures after cooling step were repeated 10 times in total. After the completion of the reaction, the reaction mixture was distilled to obtain 141 g of objective bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexane. The yield based on the amount of the starting hexafluoroacetone was 46%. Additionally, 10 g of cyclohexyl-1,1,1,3,3,3-hexafluoroisopropyl ether [b.p.: 50-54°C/3.3 kPa (23mmHg)] and 62 g of 1,1,1,3,3,3-hexafluoro-2-cyclohexyl-2-propanol [b.p.: 65-67°C/3.3 kPa (23mmHg)] were formed as major by-products. From the results shown in the foregoing, it is understood that a fluorine-substituted alicyclic diol can be prepared in a short period of time and in a high yield by the process according to the present invention wherein rhodium is used as the catalyst.

Claims: A process for preparing a fluorine-substituted alicyclic diol comprising hydrogenating a fluorine-substituted aromatic diol represented by formula (I): wherein Ph represents a divalent organic group selected from the group consisting of a phenylene group, a biphenylene group, a terphenylene group, a phenyleneoxy-phenylene group, a phenylenethiophenylene group, a phenylenealkylenephenylene group, an anthrylene group, a phenanthrylene group and said divalent organic group of which at least one hydrogen atom is substituted by a methyl group, a hydroxyl group, an amino group or a halogen atom, the alkylene group contained in said group represented by Ph having from 1 to 10 carbon atoms, in the presence of a rhodium catalyst in an amount of from 0.001 to 20 wt% based on the amount of said fluorine-substituted aromatic diol; to obtain said fluorine-substituted alicyclic diol represented by formula (II): wherein Ph(H) represents the corresponding perhydro-Ph group. The process according to claim 1, wherein said rhodium catalyst is in the form of the metal or an oxide. The process according to claim 1, wherein said rhodium catalyst is supported on a carrier selected from the group consisting of activated carbon, alumina and zeolite in an amount of from 0.01 to 30 wt% based on the total amount of said catalyst and said carrier. The process according to claim 1, wherein the reaction temperature is in the range of from 10° to 250°C. The process according to claim 4, wherein the reaction temperature is in the range of from 50° to 200°C. The process according to claim 1, wherein the hydrogen pressure of said reaction is in the range of from 0.1 to 24.5 MPa · G (1 to 250 kg/cm²G). The process according to claim 6, wherein the hydrogen pressure of said reaction is in the range of from 9.8 to 14.7 MPa · G (10 to 150 kg/cm²G).

Inventors: KUBO, MOTONOBU, SHIMIZU, YOSHIKI
Applicants: DAIKIN INDUSTRIES, LIMITED
Application year: 1988
Main classification: C07C29
IPC codes: C07C31