Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2002-10-31
2004-02-03
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
Reexamination Certificate
active
06686508
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an improved production process for bisphenol A [2,2-bis(4-hydroxyphenyl)propane], more specifically to a process for efficiently producing bisphenol A having a good hue and a high quality by reducing sulfonic acid-containing heavy matters contained in the product.
BACKGROUND ART
It is known that bisphenol A is an important compound as a raw material for engineering plastics such as a polycarbonate resin and a polyallylate resin and epoxy resins, and demand therefor tends to grow larger and larger in recent years.
This bisphenol A is produced by condensing an excess amount of phenol with acetone in the presence of an acid catalyst and a promoter such as a sulfur compound used in a certain case.
Inorganic mineral acids such as sulfuric acid and hydrochloric acid have so far been used as the acid catalyst used in this reaction. In recent years, cation exchange resins have been paid attentions (British Patents 842209, 849565 and 883391) and used in an industrial scale.
On the other hand, it is known that alkylmercaptans having a substituent or no substituent such as methylmercaptan, ethylmercaptan and thioglycolic acid are effective as the sulfur compound used as the promoter (U.S. Pat. Nos. 2,359,242 and 2,775,620). These mercaptans have functions to elevate a reaction speed and raise a selectivity. For example, in producing bisphenol A, mainly 2-(2-hydroxyphenyl)-2-(4-hydroxyphenyl)propane (o, p′-products) is formed as a reaction by-product, and in addition thereto, trisphenol and polyphenol are formed. In particular, when used as a raw material for a polycarbonate resin and a polyallylate resin, required is high quality bisphenol A which has less contents of these by-products and is not colored. Accordingly, mercaptans are used as a promoter in order to not only elevate the reaction speed but also inhibit the by-products described above from being formed and raise the selectivity.
On the other hand, it is known that an acid has such catalytic function as decomposing bisphenol A into phenol and isopropenylphenol under a high temperature condition. The representative acid includes sulfonic acid used in the production of bisphenol A using a sulfonic acid type cation exchange resin. This sulfonic acid is reacted with iron and bisphenol A at a high temperature of 120° C. or higher to thereby form a black solid sulfonic acid-containing heavy matter (hereinafter referred to as an impurity). The formation of this impurity is accelerated particularly in the presence of water. This impurity has to be effectively removed in order to provide the product bisphenol A with a good hue. Particularly in recent years, bisphenol A having less color and a higher purity than ever is required as a raw material for a polycarbonate resin which increases in demand for optical uses.
It is effective for removing the impurity described above to dispose a filter. Proposed as a technique for providing a filter in the production of bisphenol A are, for example, a process for producing bisphenol A containing only a trace amount of impurity fine particles by providing a sintered metal-made filter in a production process for bisphenol A (Japanese Patent Application Laid-Open No. 180920/1999) and a process for producing bisphenol A in which a fluororesin-made membrane filter is used to reduce impurity fine particles (Japanese Patent Application Laid-Open No. 325184/1996). In these processes, however, the filters are not necessarily disposed in preferred places because of the reasons explained above, and a hue of the product bisphenol A is not necessarily satisfactory.
Further, disclosed is a process for producing bisphenol A having less phenol content by disposing a glass fiber-made filter at least in one point of an outlet in a reaction step, an outlet in a low boiling matter-removing step and an outlet in a heating and melting step (Japanese Patent Application Laid-Open No. 327614/2000). However, if the filter-disposing place is the outlet in the reaction step or the outlet in the low boiling matter-removing step, it is impossible to completely capture sulfonic acid-containing substances, and the sulfonic acid-containing substances which can not be captured are reacted with iron and bisphenol A at a high temperature of 120° C. or higher to form a sulfonic acid-containing heavy matter. This sulfonic acid-containing heavy matter becomes a catalyst for decomposing bisphenol A under a high temperature condition in an after-step to deteriorate a hue of the product bisphenol A. Accordingly, as a melting operation is carried out on a high temperature condition in an outlet of a heating and melting step, a part thereof is considered to be decomposed. Further, a fluid temperature is high, so that a filter-cleaning work is difficult in an aspect of handling, and the heat resistance is required in the specifications of the filter. The matters described above make it less liable to consider that the three points described above are optimum filter-disposing places.
DISCLOSURE OF THE INVENTION
Under such circumstances, an object of the present invention is to provide a process for efficiently producing bisphenol A having a good hue and a high quality by reducing sulfonic acid-containing heavy matters contained in the product.
Intensive researches repeated by the present inventors in order to achieve the object described above have resulted in finding that the object can be achieved by providing a filtering step by a filter at least in one step between a step for dissolving an adduct of bisphenol A and phenol by using a phenol-containing solution and a step for crystallizing and separating the above adduct from this solution in an after step for a reaction mixed solution obtained by condensing phenol with acetone in the presence of an acid catalyst. The present invention has been completed based on such knowledge.
That is, the present invention provides a production process for bisphenol A in which carried out as essential steps after condensing excess phenol with acetone in the presence of an acid catalyst to form bisphenol A are (A) a step for condensing a reaction mixed solution containing substantially no acid catalyst described above, (B) a step for crystallizing and separating an adduct of bisphenol A and phenol from a condensed residual solution obtained in the step (A) described above, (C) a step for dissolving the adduct of bisphenol A and phenol crystallized and separated in the step (B) described above by using a phenol-containing solution, (D) a step for crystallizing and separating the adduct of bisphenol A and phenol from the solution obtained in the step (C) described above and, if necessary, repeating at least once an operation for further dissolving the above adduct by using the phenol-containing solution and then crystallizing and separating it and (E) a step for heating and melting the adduct of bisphenol A and phenol crystallized and separated in the step (D) described above and then distilling phenol off,
wherein a filtering step by a filter is provided at least in one step between the step for dissolving the adduct of bisphenol A and phenol by using the phenol-containing solution in step (C) or step (D) and the step for crystallizing and separating the above adduct from this solution.
BEST MODE FOR PRACTICING THE INVENTION
In the production process for bisphenol A of the present invention, excess phenol is condensed with acetone in the presence of an acid catalyst to form bisphenol A. An acid type ion exchange resin can be used as the acid catalyst described above. This acid type ion exchange resin shall not specifically be restricted, and those which have so far conventionally been used as a catalyst for bisphenol A can be used. In particular, a sulfonic acid type cation exchange resin is suited from the viewpoint of a catalyst activity.
The above sulfonic acid type cation exchange resin shall not specifically be restricted as long as it is a strong acid cation exchange resin having a sulfonic acid group, and it includes, for example, sul
Fujimoto Ken
Hirano Kazuyuki
Idemitsu Petrochemical Co. Ltd.
Shippen Michael L.
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