PROCESS FOR PRODUCING 2,2-BIS(4'-HYDROXYPHENYL) PROPANES

Abstract: Disclosed is a process for producing 2,2-bis(4′-hydroxyphenyl)propanes represented by the following general formula (2): (wherein R² represents hydrogen atom or a hologen atom and the four R² may be identical or different, R³ and R⁴ which may be identical or different repre­ sent hydrogen atom, an alkyl group, an aryl group, an aralkyl group, a cycloalkyl group, an alkoxy group or a halogen atom, p and q which may be identical or different represent integers of 1-4, a is 2 or 3 and b is 2 when a is 2 and is 1 when a is 3), characterized by reacting at least one phenol represented by the following formula (1): (wherein R¹ has the same meaning as R³ and R⁴ and n is an integer of 1-4) with an unsaturated carbon compound represented by the general formula: C₃R (wherein R² has the same meaning as in the formula (2) and the four R² may be identical or different) in the presence of hydrochloric acid.

Description: BACKGROUND OF THE INVENTION This invention relates to a process for production of 2,2-bis(4′-hydroxyphenyl)propanes used as starting materials for production of polycarbonate resins and epoxy resins and more particularly it relates to a process for production of 2,2-bis(4′-hydroxyphenyl)propanes by reacting a phenol compound with, for example, an unsaturated carbon compound in the presence of an acidic catalyst. For production of 2,2-bis(4′-hydroxyphenyl)propanes (sometimes referred to as "bisphenol A" hereinafter), there have been known a process comprising condensing a phenol with acetone in the presence of an ion exchange resin (cf. Japanese Patent Examined Publication No.981/62), a process comprising reacting a phenol with an aliphatic unsaturated hydrocarbon represented by the general formula C₃H₄ in the presence of, for example, Lewis acid such as boron trifluoride or aluminum trichloride or sulfuric acid (U.S.P. 2,884,462), etc. However, the process using ion exchange resin has the problems that since water which is a reaction by-product reduces the activity of the ion exchange resin, yield of bisphenol A gradually decreases when reaction is carried out continuously for a long period of time. On the other hand, the process using Lewis acid or sulfuric acid as a catalyst (U.S.P. 2,884,462) has also problems, in addition to low selectivity of bisphenol (68%), that the treatment is complicated because the Lewis acid as catalyst must be deactivated and removed by neutralization of the Lewis acid in order to obtain bisphenols of high purity. Furthermore, in this process the deactivated and removed Lewis acid cannot be repeatedly used as catalyst and hence cost of catalyst is high. In document DE-A-2 038 404 a process for producing 2,2-bis-(4-hydroxyaryl)-alkanes is described wherein the phenols are reacted with alkine in the presence of an acid catalyt which can be selected from strong anhydrous acids, preferably anhydrous hydrofluoric acid. The hydrofluoric acid is fumed with nitrogen after the reaction resulting in the fact that the catalyst cannot be recycled any more. SUMMARY OF THE INVENTION The object of this invention is to provide a process for production of bisphenols which is free from the problems such as reduction of yield of bisphenols with formation of by-products and low purity of the bisphenols obtained as seen in the process using ion exchange resin and furthermore the problems such as low selectivity of the bisphenols, complicated operation for obtaining high purity bisphenols and high cost of catalyst as seen in the process using Lewis acid and according to which selectivity of bisphenols is high, high purity bisphenols can be obtained by simple operation and besides cost of catalyst is low. As a result of the inventors' intensive researches, it has been found that above object can be accomplished by using hydrochloric acid as a catalyst in the reaction of a phenol compound and an unsaturated aliphatic hydrocarbon represented by the general formula C₃R₄ and this invention has been attained. This invention for accomplishing the above object is a process for producing 2,2-bis(4′-hydroxyphenyl)propanes (sometimes referred to as "bisphenols" hereinafter) represented by the following general formula (2): wherein R² represents hydrogen atom or a hologen atom and the four R² may be identical or different, R³ and R⁴ which may be identical or different represent hydrogen atoms, alkyl groups, aryl groups, aralkyl groups, cycloalkyl groups, alkoxy groups or halogen atoms, p and q which may be identical or different represent integers of 1-4, a is 2 or 3 and b is 2 when a is 2 and is 1 when a is 3, by reacting at least one phenol represented by the following formula (1) wherein R¹ has the same meaning as R³ and R⁴ and n is an integer of 1-4, with an unsaturated carbon compound represented by the general formula: C₃R 2 / 4 wherein R² has the same meaning as in the formula (2) and the four R² may be identical or different, in the presence of an acidic catalyst, characterized in that hydrochloric acid is used as the acidic catalyst and that the hydrochloic acid is repeatedly used. Specific embodiments of this process are defined in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a graph which shows relation between the conversion rate and selectivity of bisphenols in Examples 1-4 and Comparative Examples 1-6. DESCRIPTION OF THE INVENTION It is preferred to use sufficiently purified phenols, but those containing water may also be used as far as they do not prevent accomplishment of the object of this invention. The phenols can be represented by the following formula (1): wherein R¹ represents hydrogen atom, an alkyl group, an aryl group, an aralkyl group, cyclalkyl group, an alkoxy group or a halogen atom and n is an integer of 1-4. As examples of the phenols, mention may be made of phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, ethylphenol, propylphenol, 2-t-butylphenol 2-t-amylphenol,, 2-sec-amylphenol, 4-octylphenol, 4-nonylphenol, 2,6-dimethylphenol 2,6-diethylphenol, 2,6-diisopropylphenol, 2,6-di-t-butylphenol, di-t-amylphenol, di-sec-amylphenol, 2-phenylphenol, 2,6-diphenylphenol, 2,3-diphenylphenol, 2-benzylphenol, 2,6-dibenzylphenol, 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 2-ethoxyphenol, 3-ethoxyphenol, 4-ethoxyphenol, 2,6-diethoxyphenol 2,6-diethoxyphenol, 2-cyclohexylphenol, 2,6-dicyclohexylphenol, 2,3-dicyclohexylphenol, 2-chlorophenol, 2-fluorophenol, 2-bromophenol and 2,6-dichlorophenol, 2,6-difluorophenol, 2,6-dibromophenol. This invention is not limited to use of these exemplified phenols and there are no limitations in the number of substituent R¹ and position of substitution. When 2,2-bis(4′-hydroxyphenyl)propanes of preferable properties should be produced, it is desirable to use phenols of good symmetricalness. This is because use of phenols of good symmetricalness as a starting material can afford 2,2-bis(4′-hydroxyphenyl)propanes of good symmetricalness and 2,2-bis(4′-hydroxyphenyl)propanes of good symmetricalness can afford polycarbonates superior in mechanical properties such as heat resistances and stiffness. Therefore, phenols preferred in this invention can be represented by the following formula (3): wherein R¹ has the same meaning as above. Especially preferred among those represented by the formula (3) are as follows: 2-methylphenol, 2,6-dimethylphenol, 2-isopropylphenol, 2-methoxyphenol, 2,6-dimethoxyphenol, 2-cyclohexylphenol, 2,6-dicyclohexylphenol, 2-chlorophenol, 2,6-dichlorophenol, 2-fluorophenol, 2,6-difluorophenol, 2-bromophenol and 2,6-dibromophenol. These phenols may be used alone or in combination of two or more. When 2,2-bis(4′-hydroxyphenyl)propanes of good symmetricalness are to be produced, it is preferred to use one phenol alone. The unsaturated aliphatic carbon compounds represented by the general formula C₃R 2 / 4 include methylacetylenes represented by the following formula (4): wherein R² represents hydrogen atom or halogen atom and the four R² may be identical or different and propadienes represented by the following formula (5): wherein R² has the same meaning as above. Preferable unsaturated aliphatic carbon compounds represented by the general formula C₃R 2 / 4 are methylacetylenes represented by the formula (4) and more preferred are methylacetylene and trifluoromethylfluoroacetylene (CF₃C≡CF). In this invention, either of said methylacetylenes or propadienes may be used alone or they may be used in admixture. Hydrochloric acid used in this invention is used as an aqueous hydrochloric acid solution of usually 5-36% by weight, preferably 20-36% by weight in hydrogen chloride concentration. When concentration of hydrogen chloride is less than 5% by weight, action as a catalyst sometimes cannot be fully exhibited. In this invention, said phenols and said unsaturated aliphatic carbon compounds represented by the general formula C₃R 2 / 4 are reacted in the presence of said hydrochloric acid. This reaction can be expressed by the following equation (6): wherein R¹, R², R³, R⁴, a and b have the same meanings as above Among those bisphenols obtained by the process of this invention, preferred are those of good symmetricalness in molecular structure. As bisphenols of good symmetricalness, mention may be made of, for example, 2,2-bis(4′-hydroxyphenyl)propane, 2,2-bis(3′-methyl-4′-hydroxyphenyl)propane, 2,2-bis(3′,5-dimethyl-4′-hydroxyphenyl)propane, 2,2-bis(3′-isopropyl-4′-hydroxyphenyl)propane, 2,2-bis(3′,5-diisopropyl-4′-hydroxyphenyl)propane, 2,2-bis(3′-methoxy-4′-hydroxyphenyl)propane, 2,2-bis(3′,5-dimethoxy-4′-hydroxyphenyl)propane, 2,2-bis(3′-cyclohexyl-4′-hydroxyphenyl)propane, 2,2-bis(3′,5-dicyclohexyl-4′-hydroxyphenyl)propane, 2,2-bis(3′-chloro-4′-hydroxyphenyl)propane, 2,2-bis(3′,5-dichloro-4′-hydroxyphenyl)propane, 2,2-bis(3′-fluoro-4′-hydroxyphenyl)propane, 2,2-bis(3′,5-difluoro-4′-hydroxyphenyl)propane, 2,2-bis(3′-bromo-4′-hydroxyphenyl)propane, 2,2-bis(3′,5-dibromo-4′-hydroxyphenyl)propane, 2,2-bis(3′-methyl-4′-hydroxyphenyl)tetrahalopropane, 2,2-bis(3′,5-dimethyl-4′-hydroxyphenyl)tetrahalopropane, 2,2-bis(3′-isopropyl-4′-hydroxyphenyl) tetrahalopropane, 2,2-bis(3′,5-diisopropyl-4′-hydroxyphenyl)tetrahalopropane, 2,2-bis(3′-methoxy-4′-hydroxyphenyl)tetrahalopropane, 2,2-bis(3′,5-dimethoxy-4′-hydroxyphenyl)tetrahalopropane, 2,2-bis(3′-cyclohexyl-4′-hydroxyphenyl)tetrahalopropane, 2,2-bis(3′,5-dicyclohexyl-4′-hydroxyphenyl)tetrahalopropane, 2,2-bis(3′-chloro-4′-hydroxyphenyl)tetrahalopropane, 2,2-bis(3′,5-dichloro-4′-hydroxyphenyl)tetrahalopropane, 2,2-bis(3′-fluoro-4′-hydroxyphenyl)tetrahalopropane, 2,2-bis(3′,5-difluoro-4′hydroxyphenyl)tetrahalopropane, 2,2-bis(3′-bromo-4′-hydroxyphenyl)tetrahalopropane and 2,2-bis(3′,5-dibromo-4′-hydroxyphenyl)tetrahalopropane. Reaction temperature in this reaction is usually 30-180°C, preferably 40-100°C. When the reaction temperature is lower than 30°C, the layer containing phenols is apt to harden and when higher than 180°C, the reaction is a vapor phase reaction and so control of the reaction system becomes difficult. Reaction pressure is usually 0-98 N/cm², preferably 1-49 N/cm². The reaction may also be effected under reduced pressure. When the reaction pressure is higher than 98 N/cm², there is the tendency of increase in possibility of explosion of the unsaturated carbon compounds such as methylacetylenes. Reaction time is normally 1 hour or more, preferably 3 hours or more. When it is less than 1 hour, conversion rate of phenols decreases with decrease in selectivity of bisphenols. Amount of hydrochloric acid is adjusted so that the weight ratio hydrochloric acid/phenols is 0.1 or more, preferably 0.5-2. When the weight ratio is less than 0.1, conversion rate of phenols decreases with reduction of selectivity of bisphenols. In this invention, the reaction mixture is allowed to stand to cause separation into a layer containing phenol and a hydrochloric acid layer and hence operation for removal of hydrochloric acid is not needed. The reaction product bisphenol can be obtained from the upper phenol-containing layer by crystallization. The hydrochloric acid can be repeatedly used. The bisphenols obtained by the process of this invention are useful, for example, as starting materials for polycarbonate resins. The process for production of 2,2-bis(4′-hydroxyphenyl)propanes according to this invention has the following advantages. (1) According to the process of this invention, high purity 2,2-bis(4′-hydroxyphenyl)propanes can be produced stably for a long period of time. (2) According to the process, since the phenols and hydrochloric acid in the reaction mixtur separate into two layers only by allowing the reaction mixture to stand still, there is no need to neutralize catalyst and remove the deactivated catalyst as in the conventional process using a Lewis acid as a catalyst and besides, 2,2-bis(4′-hydroxyphenyl)propanes can be obtained from the phenol-containing layer by crystallization. Furthermore, hydrochloric acid separated from the phenol-containing layer is not deactivated and so can be repeatedly used. Therefore, this invention can provide a simple and economical process for producing 2,2-bis(4'-hydroxyphenyl)propanes. (3) According to the process of this invention, 2,2-bis(4′-hydroxyphenyl)propanes can be produced at higher selectivity than in the conventional processes. Example 1 30 g of phenol was charged in a 200 ml four-necked flask and the atmosphere in the flask was replaced with methylacetylene, followed by adding 30 g of 30 wt% hydrochloric acid with stirring to carry out the reaction at reaction temperature of 90°C for a reaction time of 5 hours. Then, the reaction mixture was left to stand still and the phenol layer (upper layer) was taken and subjected to gas chromatography assay. Reaction conditions and the results are shown in Table 1. Example 2 Example 1 was repeated except that 36 wt% hydrochloric acid was used and a reaction temperature of 75°C was employed. Reaction conditions and the results are shown in Table 1. Example 3 Example 2 was repeated except that a reaction temperature of 83°C was employed. Reaction conditions and the results are shown in Table 1. Example 4 Example 2 was repeated except that a reaction temperature of 90°C was employed. Reaction conditions and the results are shown in Table 1. Example 5 Reaction was effected under the same conditions as in Example 1 and thereafter, the reaction mixture was separated into phenol layer and hydrochloric acid layer. This phenol solution was subjected to crystallization at 50°C and the crystal was collected by filtration to obtain a 1:1 complex. Thus obtained complex crystal was subjected to distillation under reduced pressure (160°C, 665 N/m²) to remove phenol therefrom to obtain bisphenol. To the filtrate after removal of the complex crystal were added phenol in an amount corresponding to that consumed in the reaction and hydrochloric acid separated hereabove and thereafter, the reaction under the same conditions as in example 1 was repeated five times. The results are shown in Table 2. Examples 6 and 7 30 g of phenol and 30 g of 30 wt% hydrochloric acid were charged in a 500 ml of a pressure container and were heated to 90°C at normal pressures. Then, methylacetylene was introduced therein under pressure and reaction was effected under the pressure, at the temperature and for the time as shown in Table 1. The reaction mixture was treated as in Example 1. The results are shown in Table 1. Comparative Examples 1 and 2 Bisphenol was produced by conventional process which comprises reacting phenol with an unsaturated hydrocarbon represented by the general formula C₃H₄ in the presence of an ion exchange resin. Reaction conditions and the results are shown in Table 1. As is clear from Table 1, selectivity of bisphenol was lower than that in Examples 1-4. Comparative Examples 3 and 4 Bisphenol was produced by conventional process which comprises reacting phenol with an unsaturated hydrocarbon represented by the general formula C₃H₄ in the presence of sulfuric acid. Reaction conditions and the results are shown in Table 1. As is clear from Table 1, selectivity of bisphenol was lower than that in Examples 1-4. Comparative Examples 5 and 6 Bisphenol was produced by conventional process comprising reacting phenol with an unsaturated hydrocarbon represented by the general formula C₃H₄ in the presence of a Lewis acid. Reaction conditions and the results are shown in Table 1. As is evident from Table 1, selectivity of bisphenol was lower than that in Examples 1-4. Furthermore, this process was complicated because the catalyst must be deactivated and removed. In order to show the superiority of this invention, relation between conversion rate and selectivity of bisphenol in Examples 1-4 and Comparative Examples 1-6 is shown in Fig.1. Sulfuric acid catalyst and hydrochloric acid catalyst which afforded nearly the same conversion rate are considered to have nearly the same catalyst activity. As is evident from Fig.1, when selectivities in Examples of this invention and in Comparative Examples are compared, for example, at a conversion rate of 20%, those in Examples are markedly higher than those in Comparative Examples. Therefore, the process of this invention is superior in selectivity to the conventional processes.

Claims: A process for producing 2,2-bis(4'-hydroxyhenyl)propanes represented by the following general formula (2) wherein R² represents hydrogen atom or a halogen atom and four R² may be identical or different, R³ and R⁴ which may be identical or different represent hydrogen atoms, alkyl groups, aryl groups, aralkyl groups. cycloalkyl groups, alkoxy groups or halogen atoms, p and q which may be identical or different represent integers of 1-4, a is 2 or 3 and b is 2 when a is 2 and is 1 when a is 3, by reacting at least one phenol represented by the following formula (1): wherein R¹ represents a hydrogen atom, an alKyl group, an aryl group, an aralky group, a cycloalkyl group, an alkoxy group or a halogen atom and n is an integer of 1-4, with an unsaturated carbon compound represented by the general formula: C₃R²₄, wherein R² represents a hydrogen atom or a halogen atom and the four R² may be identical or different, in the presence of an acidic catalyst, characterized in that hydrochloric acid is used as the acidic catalyst and that the hydrochloric acid is repeatedly used. The process according to claim 1 wherein R¹ R³ and R⁴ are at least one group selected from the group consisting of lower alkyl group of 1-5 carbon atoms, phenyl group which may be substituted with lower alkyl group of 1-5 carbon atoms, halogen atom and hydrogen atom and R² is at least one atom selected from the group consisting of hydrogen atom and fluorine atom. The process according to claim 1 wherein R¹ , R³ and R⁴ are at least one group or atom selected from the group consisting of methyl group, hydrogen atom and bromine atom and R² is hydrogen atom. The process according to claim 1 or 2 wherein R¹, R², R³ and R⁴ are hydrogen atoms. The process according to claim 1 wherein the unsaturated carbon compound is an unsaturated hydrocarbon. The process according to claim 1 wherein the unsaturated carbon compound is methylacetylene. The process according to claim 1 wherein the hydrochloric acid is used as an aqeuous hydrochloric acid solution having a hydrogen chloride concentration of 5-36% by weight. The process according to claim 1 wherein the hydrochloric acid is used as an aqueous hydrochloric acid solution having a hydrogen chloride concentration of 20-36% by weight. The process according to claim 1 wherein the reaction pressure is 0-98 N/cm².

Inventors: NAKAGAWA, TAKASHI
Applicants: IDEMITSU PETROCHEMICAL CO. LTD.
Application year: 1987
Main classification: C07C37
IPC codes: B01J27, C07C39, C07B61, C07C27, C07C67, C07C37