Process for preparing bisphenol a (BPA) in the presence of 2-methyl benzofuran

Abstract

This invention relates to a method for preparing bisphenol A in the presence of 2-methylbenzofuran, which does not poison the catalyst system comprising an ion exchange resin catalyst and a sulfur-containing cocatalyst, wherein at least a portion of the sulfur-containing cocatalyst is neither covalently nor ionicly bonded to the ion exchange resin catalyst. Furthermore, this invention provides a method for preparing polycarbonate.

Description

[Technical Field]

[0001] This invention relates to a method for preparing bisphenol A and a method for preparing polycarbonate. [Previous Technology]

[0002] Bisphenol A or BPA is an important monomer in the manufacture of polycarbonate resins or epoxy resins. Normally, BPA is used in the form of p,p-BPA (2,2-bis(4-hydroxyphenol)propane; p,p-BPA). However, in the manufacture of BPA, ortho,o-BPA (o,o-BPA) and / or ortho,p-BPA (o,p-BPA) may also be formed. In principle, when BPA is mentioned, it means that it still contains small amounts of ortho,o-BPA and / or ortho,p-BPA's p,p-BPA.

[0003] According to the prior art, BPA is manufactured by reacting phenol with acetone in the presence of an acid catalyst to produce bisphenol. Previously, a commercial method using hydrochloric acid (HCl) for the condensation reaction was employed. Currently, a heterogeneous continuous method for manufacturing BPA is used in the presence of an ion exchange resin catalyst, wherein the ion exchange resin comprises a crosslinked, acid-functionalized polystyrene resin. The most important resin is crosslinked polystyrene with sulfonic acid groups. As described in GB849965, US4427793, EP0007791 and EP0621252 or Chemistry and properties of crosslinked polymers, edited by Santokh S. Labana, Academic Press, New York 1977, divinylbenzene is primarily used as a crosslinking agent.

[0004] To achieve high selectivity, the reaction of phenol with acetone can be carried out in the presence of a suitable co-catalyst. US2005 / 0177006 A1 and US4,859,803 describe methods for preparing bisphenol A in the presence of an ion-exchange catalyst and mercaptopropionic acid or thiol as a co-catalyst. It is known that catalysts deactivate over time. For example, deactivation reactions are described in EP0583712, EP10620041, and DE14312038. A primary objective of the manufacturing method is to maximize the performance and residence time of the catalyst system. Therefore, to achieve this objective, it is necessary to identify potential toxic substances, byproducts, impurities in the extract, etc.

[0005] WO2012 / 150560 A1 teaches a specific catalyst system comprising an ion exchange resin catalyst and a sulfur-containing cocatalyst, wherein the cocatalyst is chemically bonded to the ion exchange resin catalyst, and also teaches a method for catalyzing the condensation reaction between phenol and ketone using this specific catalyst system. Furthermore, WO2012 / 150560 A1 discloses a method for catalyzing the condensation reaction between phenol and ketone without using a bulk promoter that is not chemically bonded to the ion exchange resin catalyst.

[0006] In the same manner, EP1520617 A1 describes a method for preparing bisphenols in the presence of an acidic ion exchange resin catalyst modified with a specific cationic compound.

[0007] US8,247,619B2 describes the generation of BPA based on bio-derived phenols and / or bio-derived acetone in the presence of bio-derived impurities in the extract. This document only describes the use of ion exchange resin catalysts with linkage promoters, meaning that co-catalyst chemistry (i.e., ionic) is bound to the ion exchange resin catalyst. 2-Methylbenzofuran (2-MBF or MBF) has been found to be a common impurity in fossil fuel-derived and bio-derived phenols. It was found that the reaction of phenol with acetone was complete, and therefore no free 2-MBF was detected in the reaction product (BPA). In addition, three new MBF reaction products were observed. Furthermore, the BPA is visually pink, and polycarbonates prepared using this BPA have an unacceptable color. It was also found that the color is not caused by MBF itself, but by unknown byproducts of MBF obtained during the reaction of phenol with acetone. These unknowns could not be removed during BPA purification. Therefore, US8,247,619B2 concludes that the amount of MBF in bioderived phenols should be as low as possible to obtain low-color BPA PCs. Catalyst poisoning has not been determined in this prior art literature.

[0008] However, removing MBF from raw material phenol (fossil-based or bio-derived) is time-consuming and expensive, thus making raw material phenol more expensive. Ultimately, this increases the cost of bisphenol A and the corresponding polymers prepared from it. Furthermore, the concentration of MBF in raw material phenol depends on the supplier and their purification methods. This means that different raw material qualities need to be handled (e.g., if specifications exceed a certain threshold, another purification step is required), thereby reducing process flexibility and the choice of raw material suppliers. [Summary of the Invention]

[0009] Therefore, an object of the present invention is to provide a method for preparing ortho, para-, ortho, ortho- and / or para, para-bisphenol A via the condensation reaction of phenol and acetone, which is more economical than prior art methods. Furthermore, an object of the present invention is to provide a method for preparing ortho, para-, ortho, ortho- and / or para, para-bisphenol A via the condensation reaction of phenol and acetone, which is more flexible and / or provides greater flexibility in selecting the quality of the raw material phenol. This flexibility is preferably provided regarding the concentration of 2-methylbenzofuran as an impurity in the raw material phenol.

[0010] The present invention has solved at least one of the above-mentioned objectives, preferably all of them. Unexpectedly, it has been found that catalyst systems comprising an ion exchange resin catalyst and a sulfur-containing co-catalyst (where at least a portion of the sulfur-containing co-catalyst is neither covalently nor ionicly bonded to the ion exchange resin catalyst (not chemically bonded)) are less susceptible to poisoning by a 2-methylbenzofuran catalyst. Furthermore, prior art teaches that the amount of 2-methylbenzofuran in the feedstock phenol must be minimized as much as possible. Due to the fact that the specific catalyst system of the present invention is unaffected by this impurity, cheaper feedstock phenol can be used without the risk of reduced catalyst lifetime. This makes the entire process more cost-effective. Additionally, the method becomes more ecologically advantageous because less energy is required to purify the feedstock. Moreover, the method provides greater flexibility in selecting the quality of the feedstock phenol, particularly in the concentration of 2-methylbenzofuran in those feedstocks.

[0011] Furthermore, prior art teaches the use of a catalyst system comprising an ionic bond between an ion exchange resin and a co-catalyst, in which MBF reacts completely during the reaction of acetone and phenol. The resulting MBF byproduct negatively impacts the color of BPA and the resulting BPA PC. Surprisingly, it has been found that when using a catalyst system comprising an ion exchange resin catalyst and a sulfur-containing co-catalyst, wherein at least a portion, preferably at least 75 mol-%, of the sulfur-containing co-catalyst is neither covalently nor ionicly bonded to the ion exchange resin catalyst, the formation of such MBF byproducts can be reduced. This means that some MBF present during the reaction is also present in the resulting BPA. Forewords have demonstrated that MBF itself does not significantly affect the color of BPA and the resulting BPA PC. Therefore, using the catalyst system of the present invention, it is possible to accept higher amounts of MBF in the feedstock phenol without significantly affecting the color of the resulting BPA and BPA PC. This again means that the entire process becomes more cost-effective. In addition, the method becomes more ecologically advantageous because less energy is required to purify the feedstock. Furthermore, the method offers greater flexibility in selecting the quality of the raw material phenol, particularly in the concentration of 2-methylbenzofuran in these raw materials.

[0012] Therefore, the present invention provides a method for preparing ortho, para-, ortho, ortho- and / or para, para-bisphenol A, comprising the following steps: (a) condensing raw material phenol and raw material acetone in the presence of a catalyst system, wherein the catalyst system comprises an ion exchange resin catalyst and a sulfur-containing cocatalyst, wherein at least a portion, preferably 75 mol-%, of the sulfur-containing cocatalyst is neither covalently bonded nor ionically bonded to the ion exchange resin catalyst at the beginning of step (a), characterized in that the amount of 2-methylbenzofuran present in step (a) is higher than 1 ppm relative to the total weight of the raw material phenol.

[0013] According to the present invention, the term "raw material" refers to "phenol" and / or "raw material acetone". The term "raw material" is used for unreacted extracts, particularly those applied (especially added) during the preparation of BPA. In particular, this term is used to distinguish between freshly added phenol to the reaction (as raw material phenol) and phenol recycled during the preparation of BPA (recycled phenol). Such recycled phenol cannot add additional MBF to the method. The same applies to acetone freshly added to the reaction (as raw material acetone) and acetone recycled during the preparation of BPA (recycled acetone). When phenol and / or acetone are mentioned without further explanation, it is preferable to refer to the compound itself or the sum of the raw material and recycled phenol and / or the raw material and recycled acetone.

[0014] MBF is an impurity in the raw material phenol, and it is one of the extracts from the BPA reaction. The raw material phenol may contain MBF impurities. For example, the route for the production of phenol is described in Arpe, Hans-Jürgen, Industrielle Organische Chemie, 6. Auflage, Januar 2007, Wiley-VCH. In particular, the method for preparing phenol is described in Ullmann's Encyclopedia of Industrial Chemistry, chapters Phenol and Phenol derivatives. The oxidation of cumene (also known as the Hock method) is the main synthetic route for phenol to date. The contaminant formed during the production of phenol is 2-methylbenzofuran.

[0015] In addition, US8,247,619B2 describes at least one method of providing bio-derived phenol, said phenol further comprising MBF as an impurity.

[0016] The method of the present invention is characterized in that the amount of 2-methylbenzofuran present in step (a) is higher than 1 ppm, more preferably higher than 2 ppm, more preferably higher than 3 ppm, more preferably higher than 4 ppm, more preferably higher than 5 ppm, more preferably higher than 6 ppm, more preferably higher than 7 ppm, more preferably higher than 8 ppm, more preferably higher than 9 ppm, more preferably higher than 10 ppm, more preferably higher than 11 ppm, more preferably higher than 12 ppm, more preferably higher than 13 ppm, more preferably higher than 14 ppm, more preferably higher than 15 ppm, more preferably higher than 20 ppm, more preferably higher than 25 ppm, and most preferably higher than 50 ppm, relative to the total weight of the raw material phenol.

[0017] Furthermore, preferably, the amount of MBF present in step (a) relative to the total weight of the raw material phenol is greater than 1 ppm and equal to or less than 5000 ppm, more preferably equal to or less than 4500 ppm, even more preferably equal to or less than 4000 ppm, even more preferably equal to or less than 3500 ppm, even more preferably equal to or less than 3000 ppm, even more preferably equal to or less than 2500 ppm, and most preferably equal to or less than 2000 ppm. It is understood that the upper limits given herein can be combined with the preferred lower limits given above. Those skilled in the art know how to determine the amount of MBF in the raw material phenol. For example, the amount of 2-methylbenzofuran in the raw material phenol can be determined according to ASTM D6142-12 (2013).

[0018] According to the present invention, "ppm" preferably means parts by weight.

[0019] According to the present invention, it was found that a byproduct was formed in reaction step (a) due to the presence of MBF. However, not all MBF reacts with this impurity. This means that MBF does not react completely with this impurity. This new byproduct was analyzed by MS and a molecular weight of 226 g / mol was detected. This indicates the atomic formula of C15H14O2. Without being bound by theory, phenol may react with MBF. However, since no deactivation of the catalyst was observed, this impurity (and all other possible impurities) does not appear to poison the catalyst, at least in small amounts. Therefore, it is preferable that step (a) is carried out in the presence of at least one additional impurity formed due to the presence of MBF in method step (a). Furthermore, if the phenol fraction from step (b) is recycled in method step (c), such impurities may be present in method step (a).

[0020] More preferably, the method of the present invention is characterized in that 2-methylbenzofuran is present throughout method step (a). As described above, according to the present invention, it has been found that MBF is not completely reacted during method step (a) when the catalyst system of the present invention is used. This means that some MBF is still present in BPA. Preferably at least 5 wt.-%, more preferably at least 10 wt.-%, and most preferably at least 15 wt.-% of the MBF present at the beginning of method step (a) is also present at the end of method step (a), and preferably at the beginning of method step (b) below. Preferably at least 5 wt.-%, more preferably at least 10 wt.-%, and most preferably at least 15 wt.-% of the MBF present at the beginning of method step (a) is present in the resulting ortho, para-, ortho, ortho- or para, para-bisphenol A.

[0021] Preferably, the method of the present invention is characterized in that the method further comprises the following steps: (b) separating the mixture obtained after step (a) into a bisphenol A fraction containing at least one of ortho-, para-, ortho-, or para-, para-bisphenol A and a phenol fraction, wherein the phenol fraction contains unreacted phenol and at least one impurity formed due to the presence of 2-methylbenzofuran in step (a).

[0022] Preferably, the bisphenol A fraction is used as a product and / or further purified. Several variations of manufacturing methods exist to provide high-purity bisphenol. This high purity is particularly important for the use of BPA as a monomer in polycarbonate manufacturing. WO-A 0172677 describes the crystallization of the adduct of bisphenol and phenol, and a method for producing the crystals and ultimately preparing bisphenol. It has been found that high-purity p,p-BPA can be obtained by crystallizing the adducts. EP1944284 describes a method for producing bisphenol, wherein crystallization comprises a continuous suspension crystallization apparatus. It mentions the increased requirement for BPA purity, and that by the method disclosed therein, very pure BPA exceeding 99.7% can be obtained. WO-A 2005075397 describes a method for producing bisphenol A, wherein water generated during the reaction is removed by distillation. By this method, unreacted acetone is recovered and recycled, thus achieving an economically advantageous method.

[0023] Preferably, the method of the present invention is characterized in that the separation system in step (b) is carried out using crystallization technology. More preferably, the separation system in step (b) is carried out using at least one continuous suspension crystallization device.

[0024] The use of a mother liquor cycle has been further described. After the reaction, BPA is removed from the solvent by crystallization and filtration. The mother liquor typically contains 5 to 20% BPA and byproducts dissolved in unreacted phenol. Additionally, water is formed during the reaction and removed from the mother liquor in a dehydration zone. Preferably, the fraction containing unreacted phenol is recycled for further reaction. Preferably, this means the mother liquor is recycled. In the reaction with acetone, it is reused as unreacted phenol to generate BPA. The mother liquor stream is preferably recycled back to the reaction unit in a conventional manner.

[0025] Typically, byproducts in the mother liquor are, for example, o,p-BPA, o,o-BPA, substituted indene, hydroxyphenyl indanoles, hydroxyphenyl alkylene, substituted dibenzopiperanone, and compounds with higher condensation. Additionally, due to the self-condensation of acetone and its reaction with impurities in the raw materials, other secondary compounds may be formed, such as anisole, mesityl oxide, mesitylene, and diacetone alcohol.

[0026] Due to the circulation of the mother liquor, byproducts accumulate in the circulating stream and can lead to additional deactivation of the catalyst system. This means that to extend the service life of the catalyst, the effects of initial impurities in the extract and the effects of byproducts that may be generated by the reaction itself must be taken into account. These byproducts are derived from the reaction of phenol and acetone or from one of the impurities of the reaction.

[0027] More preferably, the method of the present invention is characterized in that the method includes the additional step of: (c) using at least a portion of the phenol fraction obtained in step (b) as the extract in step (a).

[0028] More preferably, the phenol fraction contains at least 5 wt.-%, more preferably at least 10 wt.-%, and most preferably at least 15 wt.-% MBF, wherein the weight percentage of MBF refers to the portion of MBF (compared to MBF present in the raw phenol).

[0029] To avoid the accumulation of byproducts and / or impurities in the system due to the presence of MBF in step (a), several options exist. These options include a purge stream, wastewater, exhaust gas, and BPA as a product itself. The primary option appears to be a purge stream, for example, discharging a portion of the mother liquor. Another method involves passing a portion of the total circulating stream through a rearrangement unit, for example, packed with an acid ion exchanger, after solid / liquid separation and before or after the removal of water and residual acetone. In this rearrangement unit, some byproducts from BPA preparation are isomerized to obtain p,p-BPA. It is assumed that new impurities formed in step (a) due to the presence of MBF can be removed by the purge stream. Therefore, it is preferable to use at least a portion of the phenol fraction obtained in step (b) as the extract in step (a), wherein at least a portion of this stream is flushed out. Preferably, the phenol fraction obtained in step (b) of greater than 50 vol.-% is used as the extract in step (a), wherein vol.-% is based on the total volume of the phenol fraction.

[0030] The catalyst system that can be used in the method of the present invention is known to those skilled in the art. Preferably, it is an acidic ion exchange resin. This ion exchange resin may have 2% to 20%, more preferably 3% to 10%, and most preferably 3.5% to 5.5% crosslinking. The acidic ion exchange resin is preferably selected from the group consisting of sulfonated styrene-divinylbenzene resin, sulfonated styrene resin, phenol-formaldehyde sulfonic acid resin, and benzaldehyde sulfonic acid. In addition, the ion exchange resin may contain sulfonic acid groups. The catalyst bed may be a fixed bed or a fluidized bed.

[0031] Furthermore, the catalyst system of the present invention comprises a sulfur-containing cocatalyst, wherein at least a portion of the sulfur-containing cocatalyst is neither covalently bonded nor ionicly bonded to the ion exchange resin catalyst. The sulfur-containing cocatalyst may be a single substance or a mixture of at least two substances. This cocatalyst is preferably dissolved in the reaction solution of step (a) of method. More preferably, the cocatalyst is uniformly dissolved in the reaction solution of step (a) of method. Preferably, the method of the present invention is characterized in that the sulfur-containing cocatalyst is selected from the group consisting of mercaptopropionic acid, hydrogen sulfide, alkyl sulfides (such as diethyl sulfide), and mixtures thereof. Most preferably, the sulfur-containing cocatalyst is 3-mercaptopropionic acid.

[0032] Preferably, the catalyst system of the present invention comprises a sulfur-containing cocatalyst, wherein all sulfur-containing cocatalysts are neither covalently bonded nor ionicly bonded to the ion exchange resin catalyst. This means that preferably all sulfur-containing cocatalysts are added to step (a). According to the present invention, the expression "not chemically bonded" or "neither covalently bonded nor ionicly bonded" means that at the beginning of method step (a), there are neither covalent bonds nor ionic bonds between the ion exchange resin catalyst and the sulfur-containing cocatalyst. However, this does not mean that at least some of the sulfur-containing cocatalysts may be fixed on the heterogeneous catalyst matrix via ionic or covalent bonds. Nevertheless, at the beginning of method step (a), there are no such ionic or covalent bonds in the sulfur-containing cocatalyst, but if they eventually form, they do so over time. Therefore, it is preferable to add the sulfur-containing cocatalyst to method step (a). The term "addition" describes an effective method step. As mentioned above, this means that it is preferable to dissolve the cocatalyst in the reaction solution of method step (a). Furthermore, the co-catalyst may be added in any other method step, or even added two or more times in method step (a). Moreover, preferably, most of the sulfur-containing co-catalyst is neither covalently nor ionicly bonded to the ion exchange resin catalyst. This means that at least 75 mol-%, more preferably at least 80 mol-%, and most preferably at least 90 mol-%, of the sulfur-containing co-catalyst is not chemically bonded to the ion exchange resin catalyst. Here, mol-% relates to the total amount of co-catalyst present in method step (a).

[0033] Since MBF is a common impurity in the raw material phenol, it is preferable to introduce the MBF present in step (a) as an impurity in the raw material phenol into method step (a). Nevertheless, for other reasons, at least some of the MBF may be present in method step (a). For example, some of the MBF present in method step (a) may be present due to the recycling of phenol.

[0034] More preferably, the method of the present invention is characterized in that the phenol used in step (a) of the method is bio-based. More preferably, the phenol used as a raw material containing MBF as an impurity is bio-based.

[0035] As used in this invention, the terms "bio-derived" or "bio-based" mean phenol derived from currently renewable resources. In particular, this term is used differently from fossil fuel-derived phenol. The fact that a raw material is bio-based can be verified by measuring carbon isotope levels, as the relative amount of carbon C14 isotope is lower in fossil fuel materials. Such measurements are known to those skilled in the art to be performed, for example, according to ASTM D6866-18 (2018) or ISO 16620-1 to -5 (2015).

[0036] Another aspect of the present invention provides a method for preparing polycarbonate, comprising the following steps: (i) obtaining ortho-, para-, ortho-, ortho- and / or para-, para-bisphenol A according to the method of the present invention in any particular embodiment or preferred embodiment, and (ii) polymerizing the ortho-, para-, ortho-, ortho- and / or para-, para-bisphenol A obtained in step (i) to obtain polycarbonate in the presence of at least one additional monomer, as appropriate.

[0037] As described above, the method of the present invention for manufacturing ortho, para-, ortho, ortho- and / or para, para-bisphenol A provides a BPA that can be obtained in a more economical and / or ecological manner. Therefore, the method for preparing the polycarbonate of the present invention is also more economical and / or ecological when using such a BPA obtained by the method according to the present invention.

[0038] Reaction step (ii) is known to those skilled in the art. Polycarbonate can be prepared in a known manner from BPA, a carbonate derivative, an arbitrary chain terminator and an arbitrary branching agent by alternating phosgenation or melt transesterification.

[0039] In interphase phosgenation, bisphenol and any branching agent are dissolved in an alkaline aqueous solution and reacted with a carbonate source (such as phosgene) dissolved in a solvent in a two-phase mixture comprising the alkaline aqueous solution, an organic solvent, and a catalyst (preferably a methamine compound). The reaction process can also be carried out in multiple stages. Such methods for preparing polycarbonates are in principle called interfacial methods, as known for example from H. Schnell, Chemistry and Physics of Polycarbonates, Polymer Reviews, Vol. 9, Interscience Publishers, New York 1964, page 33 et seq., and Polymer Reviews, Vol. 10, “Condensation Polymers by Interfacial and Solution Methods”, Paul W. Morgan, Interscience Publishers, New York 1965, chapter VIII, page 325, and therefore the basic conditions are known to those skilled in the art.

[0040] Alternatively, polycarbonate can be prepared by melt transesterification. Melt transesterification is described, for example, in Encyclopaedia of Polymer Science, Vol. 10 (1969), Chemistry and Physics of Polycarbonates, Polymer Reviews, H. Schnell, Vol. 9, John Wiley and Sons, Inc. (1964), and DE-C 10 31 512. In melt transesterification, an aromatic dihydroxy compound, as described in the interfacial method, undergoes transesterification with a carbonate diester in the melt using a suitable catalyst and any other additives.

[0041] Preferably, the method for preparing polycarbonate according to the present invention is characterized in that step (i) further comprises purifying ortho-, para-, ortho-, ortho- and / or para-, para-bisphenol A to reduce the amount of at least one impurity formed due to the presence of MBF in step (a). As mentioned above, inexpensive raw material phenol can be used in the method of the present invention. However, when such inexpensive raw materials contain MBF impurities, other impurities will be formed. These impurities are preferably removed before polymerization.

Implementation Method

[0043] Example

[0044] Materials used in the embodiments: catalyst Resin primarily composed of acidic polymers with sulfonic acid groups (polystyrene-divinylbenzene), spherical beads, 4% crosslinking. phenol Acros Organics, Grade: Extra Pure > 99% (Purity measured by GC: 99.9%) MEPA 3-Mercaptopropionic acid, Sigma-Aldrich, purity > 99% (purity measured by GC: 99.3%) acetone VWR, GPR rectapur > 99.5% (purity measured by GC: 100%, anhydrous) 2-Methylbenzofuran Sigma Aldrich, 99.0% purity methanol Fisher analytical grade; GC purity 99.99%

[0045] The column reactor is equipped with 150 g of wet phenol catalyst (volume of wet phenol catalyst in the reactor: 210 to 230 ml). The column reactor is heated to 60°C (catalyst bed temperature during the reaction: 63°C). A mixture of phenol, acetone (3.9 wt.-%), and MEPA (160 ppm relative to the sum of the masses of phenol and acetone) is prepared and tempered to 60°C. This mixture is pumped into the column reactor at a flow rate of 45 g / h. A sampling point is provided at the bottom of the column reactor. Different samples are collected during the reaction using the orifice of the sampling point. The sampling time is 1 hour, and the sample volume collected per hour is 45 g.

[0046] The first run (standard run) was performed for 52 hours. Samples were taken and analyzed by GC at 48, 49, 50 and 51 hours respectively.

[0047] A second run (impurity run) was conducted for 52 hours. At the start of the second run, 1590 ppm (relative to the sum of the masses of phenol and acetone) of 2-methylbenzofuran was added to the reaction system. Samples were taken and analyzed by GC at 48, 49, 50, and 51 hours. Subsequently, a third run (standard run) was conducted for 52 hours using a fresh mixture of acetone, phenol, and MEPA. Samples were taken via syringe and analyzed by GC at 48, 49, 50, and 51 hours. Subsequently, a fourth run (impurity run) was conducted for 52 hours. At the start of the fourth run, 1580 ppm (relative to the sum of the masses of phenol and acetone) of 2-methylbenzofuran was added to the reaction system. Samples were taken and analyzed by GC at 48, 49, 50, and 51 hours. Finally, a fifth run (standard run) was conducted for 52 hours. Samples were collected and analyzed by GC at 48, 49, 50 and 51 hours, respectively.

[0048] The methanol gas chromatography (GC) was performed as follows: an Agilent J&W VF-1MS column (100% dimethyl polysiloxane) with dimensions of 50 m x 0.25 mm x 0.25 μm was used. The temperature profile was 60°C for 0.10 min, heated to 320°C at 12°C / min, and maintained at this temperature for 10.00 min. 1 µl was injected at 300°C at a split flow rate of 10 / 1, with a flow rate of 2 ml / min and an initial pressure of 18.3 psi (1.26 bar).

[0049] The gas chromatography (GC) of 2-methylbenzofuran, phenol, and p,p-BPA was performed as follows: An Agilent J&W VF-1MS column (100% dimethylpolysiloxane) with dimensions of 50 m x 0.25 mm x 0.25 μm was used. The temperature profile was 80 °C for 0.10 min, heated to 320 °C at 12 °C / min, and held at this temperature for 10.00 min; 1 μl was injected at 300 °C at a split flow rate of 10 / 1; the flow rate was 2 ml / min, and the initial pressure was 18.3 psi (1.26 bar).

[0050] The following method was used to identify an unknown compound by combining gas chromatography (GC) and mass spectrometry (MS): An Agilent J&W VF-1MS column (100% dimethyl polysiloxane) with dimensions of 30 m x 0.25 mm x 0.25 µm was used. The temperature profile was 60 °C for 0.10 min, heated to 350 °C at 12 °C / min, and held at this temperature for 5 min. 0.5 μl was injected at 250 °C at a split flow rate of 10 / 1. The flow rate was 1 ml / min, the initial pressure was 24.45 psi (1.685768 bar), and the mass spectrometer scan was from mz 35 to mz 700.

[0051] The standard run represents the reaction of acetone and phenol to produce BPA in the presence of a catalyst and a co-catalyst. Based on this, the acetone conversion can be estimated, including its respective error threshold. This conversion represents the baseline for assessing whether impurities affect catalyst deactivation. The acetone conversions of standard runs 3 and 5 are compared with the value of standard run 1 to determine the effect of 2-methylbenzofuran on the catalyst. If the acetone conversion decreases from this conversion, it demonstrates that 2-methylbenzofuran has an effect on the BPA catalyst. To show that this assessment can be used to determine catalyst poisoning, a reference run is performed using methanol as an impurity. Methanol is a known poison for catalysts in the BPA process, as known from the prior art, and is described, for example, in US-B 8,143,456. Table 1 shows the results obtained. The values ​​given in the table are averages obtained from four samples collected during each run (after 48, 49, 50, and 51 hours). Table 1: Reference Run Using Methanol substance unit First run (standard run) Second run (impurity run) Third run (standard run) Fourth run (impurity run) Fifth run (standard run) Acetone conversion rate % 82.63 78.65 81.92 78.20 79.42 Methanol IN** mg / kg - 1710 - 1660 - ** The amount of methanol (IN) is measured before the catalyst.

[0052] As can be clearly seen from Table 1, the acetone conversion rate decreased in each standard operation 1, 3 and 5. This means that the catalyst was poisoned by methanol, and the irreversible reaction reduced the catalyst activity, so the conversion rate could not be recovered.

[0053] The table below shows the results of the first run (standard run), second run (impurity run), third run (standard run), fourth run (impurity run), and fifth run (standard run) using 2-methylbenzofuran as an impurity. The values ​​given in the table are averages obtained from four samples collected during each run (after 48, 49, 50, and 51 hours). Table 2: 2-Methylbenzofuran substance unit First run (standard run) Second run (impurity run) Third run (standard run) Fourth run (impurity run) Fifth run (standard run) Acetone conversion rate % 83.53 83.27 81.54 83.72 81.47 2-Methylbenzofuran IN** mg / kg - 1590 1580 2-Methylbenzofuran OUT** mg / kg - 328.50 333.75 Unknown compound % - 0.22 - 0.27 - ** The amount of 2-methylbenzofuran IN was measured before the catalyst. The amount of 2-methylbenzofuran OUT was measured from four samples collected during each operation period (after 48, 49, 50 and 51 hours; average).

[0054] As can be seen from the results in Table 2, the addition of 2-methylbenzofuran in the reaction of phenol with acetone (para-, para-BPA) did not lead to a decrease in acetone conversion in standard runs 1, 3, and 5. This means that MBF is non-toxic to the catalyst system used. This effect was observed after each impurity run. Furthermore, it can be seen that some MBF still left the reactor during the impurity run (2-methylbenzofuran OUT was detected). This means that not all MBF reacted during the impurity run. In addition, at least one unknown compound with a molecular weight of 226 g / mol was found. [Simplified Explanation of the Diagram]

[0042] None. [Biomaterial Storage]

[0056] None.

Claims

1. A method for preparing ortho, para-, ortho, ortho- and / or para, para-bisphenol A, comprising the following steps: (a) condensing raw material phenol and raw material acetone in the presence of a catalyst system, wherein the catalyst system comprises an ion exchange resin catalyst and a sulfur-containing cocatalyst, wherein at least a portion of the sulfur-containing cocatalyst is neither covalently bonded nor ionically bonded to the ion exchange resin catalyst at the beginning of step (a); (b) separating the mixture obtained after step (a) into a bisphenol A fraction comprising at least one of ortho, para-, ortho, or para, para-bisphenol A and a phenol fraction, wherein the phenol fraction comprises unreacted phenol and at least one impurity formed due to the presence of 2-methylbenzofuran in step (a); (c) using at least a portion of the phenol fraction obtained in step (b) as the extract in step (a), characterized in that the amount of 2-methylbenzofuran present in step (a) is greater than 1 ppm relative to the total weight of the raw material phenol.

2. The method of claim 1, characterized in that, relative to the total weight of the raw material phenol, the amount of 2-methylbenzofuran present in step (a) is higher than 1 ppm and equal to or lower than 5000 ppm.

3. The method of claim 1 or 2, characterized in that step (a) is carried out in the presence of at least one impurity formed due to the presence of 2-methylbenzofuran in step (a).

4. The method of claim 1 or 2, characterized in that the 2-methylbenzofuran system is present throughout step (a) of the method.

5. The method of claim 1 or 2, characterized in that at least 75 mol% of the sulfur-containing cocatalyst is neither covalently bonded nor ionically bonded to the ion exchange resin catalyst at the beginning of step (a) of the method.

6. The method of claim 1, characterized in that the separation system in step (b) is carried out using crystallization technology.

7. The method of claim 1 or 2, characterized in that the sulfur-containing cocatalyst is selected from the group consisting of mercaptopropionic acid, hydrogen sulfide, alkyl sulfides and mixtures thereof.

8. The method of claim 1 or 2, characterized in that the 2-methylbenzofuran present in step (a) is introduced into step (a) as an impurity in the raw material phenol.

9. The method of claim 8, characterized in that the raw material phenol is bio-based.

10. A method for preparing polycarbonate, comprising the steps of: (i) obtaining ortho, para-, ortho, ortho- and / or para, para-bisphenol A according to any one of claims 1 to 9, and (ii) polymerizing the ortho, para-, ortho, ortho- and / or para, para-bisphenol A obtained in step (i) in the presence of at least one additional monomer to obtain polycarbonate.

11. The method of claim 10, characterized in that step (i) further comprises purifying ortho, para-, ortho, ortho- and / or para, para-bisphenol A to reduce the amount of at least one impurity formed due to the presence of 2-methylbenzofuran in step (a).