CN1163880A - Process for recovering bisphenols - Google Patents

Abstract

A method for recovering substantially pure p,p-bisarylols from a mixture comprising the same by subjecting the mixture to vacuum distillation and melt crystallization in the absence of an adduct crystallization and the generation of a reaction recycle stream.

Description

Method for recovering bisphenol

The present invention relates to a novel process for the recovery of substantially pure p,p-diarylphenols. More specifically, the present invention relates to the recovery of p, p-bisphenols such as 2,2-bis(4-hydroxyphenyl)propane (BPA) by treating mixtures containing p,p-bisphenol Phenols, wherein the process does not require operations including crystallization separation of the adduct and generation of a reaction recycle stream.

Polycarbonates are a well-known class of high-impact thermoplastic resins characterized by optical clarity, high toughness, and other superior properties. They are often used as lenses and windows for their transparency. Bisphenol A polycarbonate is the main variety of this resin commercially available. It generally has a glass transition temperature of about 150°C and is derived from 2,2-bis(4-hydroxyphenyl)propane.

For example, 2,2-bis(4-hydroxyphenyl)propane is commercially available and can typically be obtained from phenol and acetone to prepare. This method is characterized by the need for cumbersome, costly and potentially harmful processing steps in order to recover the desired bisphenols.

There is growing interest in the recovery of p,p-diarylphenols by processes which do not require the use of unfavorable processing steps. Accordingly, the present invention relates to a novel process for the recovery of substantially pure p,p-diarylphenols which does not require operations involving crystallization separation of the adduct and generation of a reaction recycle stream.

Attempts to prepare BPA monomer have been published. In US Pat. No. 3,394,089, BPA monomer is prepared from ketones and phenols in the presence of strongly acidic cation exchange resins.

Other attempts to prepare BPA monomer have also been disclosed. In the Encyclopedia of Chemical Processing and Design (Encyclopedia of Chemical Processing and Design) Volume 4, pages 407-430 (1977), the preparation process of BPA is described.

The present invention relates to a method for recovering substantially pure p-diarylphenols comprising the steps of:

(a) vacuum distilling a mixture containing p-diarylphenols to obtain distillates and residues; and

(b) subjecting the residue to melt crystallization to obtain substantially pure p,p-diarylphenol.

In the present invention, it has surprisingly been found that substantially pure p, p, p-Diepiarylphenol. "Substantially pure" is defined herein to mean at least about 90% pure, more preferably at least about 95% pure, and most preferably at least about 99% pure. A reaction recycle stream as defined herein means a stream containing impurities which is returned to the feed for further reaction in the process and which is the source of the p,p-diarylphenol containing mixture.

There is basically no restriction on the kind of p,p-diarylphenol to be recovered by the method of the present invention. Usually, they are represented by the following general formula:

HO-A ¹ -Yt-A ² -OH wherein A ¹ and A ² are each independently a substituted or unsubstituted divalent aryl group, and Y is a bridging group such as a hydrocarbon group, more specifically such as a methylene group, Cyclohexylmethylene, 2-[2.2.1]-bicycloheptylmethylene, 1,2-ethylene, isopropylidene, neopentylene, cyclohexylene, cyclopentadecylene , a saturated group of cyclododecylene or adamantylene, especially a geminal alkylene (alkylene), and most usually (CR) ₂ , wherein each R is independently C _1-5 alkyl, More preferably methyl. The t-value is 0 or 1.

Illustrative, non-limiting examples of p,p-diarylphenols represented by the general formula above include:

2,2-bis(4-hydroxyphenyl)propane (bisphenol A);

2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane;

2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane;

1,1-bis(4-hydroxyphenyl)cyclohexane;

1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclohexane;

1,1-bis(4-hydroxyphenyl)decane;

1,4-bis(4-hydroxyphenyl)propane;

1,1-bis(4-hydroxyphenyl)cyclododecane;

1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclododecane;

4,4-Dihydroxydiphenyl ether;

4,4-dihydroxydiphenyl sulfide;

4,4-di-hydroxy-3,3-dichlorodiphenyl ether; and

4,4-dihydroxy-3,3-dihydroxydiphenyl ether

9,9-bis(4-hydroxyphenyl)fluorene;

There is essentially no restriction on the source of the p,p-diarylphenol-containing mixture to be recovered in accordance with the present invention. The only limitation with regard to the mixtures is that they are preferably produced by processes normally used to prepare the p,p-diarylphenols in substantially pure form to be recovered by the present invention.

For example, the mixture used in the present invention may be a reaction mixture obtained from the reaction of an arylphenol, such as phenol, with a ketone, such as acetone, to form BPA. The process often adds acetone and phenol to a reactor containing an acidic ion-exchange resin catalyst such as sulfonated polystyrene, along with a bulk (one-time addition with the reactants) promoter such as 3-mercaptopropionic acid middle. Generally, no more than about 35 moles, more preferably no more than about 25 moles, and most preferably is not more than about 15 moles of arylphenol.

A more detailed description of the use of 3-mercaptopropionic acid to prepare BPA can be found in US Patent 2,468,982, the disclosure of which is incorporated herein by reference.

Additionally, it is within the scope of this invention to use mixtures containing p,p-diarylphenols prepared by adding an effective amount of any conventional packing accelerator in an acid-catalyzed condensation reaction. Such packing promoters include methyl or ethyl mercaptans, and they can also be fed with arylphenols and ketones to the reactor containing the acidic ion exchange resin catalyst.

In a preferred embodiment of the invention, it is desirable to use a mixture which is produced by treating the acidic ion exchange resin with a sulfur-containing accelerator prior to any arylphenols and ketones being added to the reactor. In this case, the sulfur-containing promoter is an attachable accelerator, so defined that the accelerator is either covalently or ionically attached/bonded to the acidic ion exchange resin catalyst.

There is essentially no restriction on the type of sulfur-containing promoter attached to the acidic ion exchange resin catalyst, as long as the reaction is promoted by the thiol after attachment. Typically, the accelerator is attached to the resin via, for example, an ammonium sulfonate linkage or a sulfonamide linkage. Illustrative examples of sulfur-containing accelerators that may be used include C _1-4 aminoalkanethiols, especially 2-aminoethanethiol.

The acidic ion exchange resin catalyst can be treated by adding the promoter to the aqueous slurry of the resin catalyst, thereby attaching the promoter to the catalyst. A more detailed description of catalyst treatment can be found in US Patent 3,394,089, the disclosure of which is incorporated herein by reference.

After attachment of a sulfur-containing promoter to an acidic ion exchange resin catalyst, the catalyst is generally considered to be partially neutralized. When partially neutralized, generally not more than about 50%, more preferably not more than about 20%, of the total acid groups on the acidic ion exchange resin catalyst are neutralized.

In the most preferred embodiment of the invention, the process for the preparation of mixtures containing p,p-diarylphenols recovered in substantially pure state employs a catalyst having an attachable promoter as described above and the staged addition of the ketone.

This staged addition of ketone as defined herein means that when arylphenol and ketone are added to a reactor containing a catalyst with an attachable promoter, no more than about 50% of the total moles of ketone used , more preferably not more than about 30%, most preferably not more than about 10% is added to the reactor at the beginning of the condensation reaction, and up to about 65% of the total moles of ketone used is at the end of the condensation reaction. Add at no more than about 70% of complete condensation. The remaining ketone was added thereafter.

There is no particular limitation on the form containing the mixture of p,p-diarylphenols before carrying out the steps described in (a) and (b). Thus, the p,p-diarylphenol-containing mixture may be in solid state, molten state or solution.

Typically, in the present invention, the mixture subject to the steps described in (a) and (b) also contains o, p-BPA, chroman, such as 4-(3,4-dihydro-2 , 4,4-trimethyl-2H-1-benzopyran-2-yl)-phenol and 4-(3,4-dihydro-2,2,4-trimethyl-2H-1-benzene pyran-2-yl)-phenols and triarylphenols, such as 2,4-bis[1-(4-hydroxyphenyl)-1-methylethyl]-phenol. However, they are preferably substantially composed of p, p-BPA, o, p-BPA, chroman, such as 4-(3,4-dihydro-2,4,4-trimethyl-2H -1-benzopyran-2-yl)-phenol and 4-(3,4-dihydro-2,2,4-trimethyl-2H-1-benzopyran-2-yl)-phenol and triarylphenols, such as 2,4-bis[1-(4-hydroxyphenyl)-1-methylethyl]-phenol.

When carrying out the present invention, contain right, the mixture of p-diaryl phenols is fed into at first can contain right, the mixture of p-diaryl phenols is distilled and obtains rich in right, p-diarylphenols residue In the device/equipment of the object. The apparatus/equipment is not limited and is generally an apparatus comprising a reduced pressure source, a heat source, a distillation flask and a condenser.

There is basically no limitation on the distillation temperature as long as the temperature does not cause decomposition of p,p-diarylphenol and is not higher than the boiling point of p,p-diarylphenol at the distillation pressure. Distillation is usually carried out at a pressure not higher than about 300 Torr, more preferably not higher than 100 Torr, and most preferably not higher than about 10 Torr.

Following the distillation step, the resulting p,p-diarylphenol-containing residue is subjected to melt crystallization. Any equipment capable of removing impurities from the residue melt can be used. Usually melt crystallization is accomplished by zone melting or zone (melt crystallization) refining equipment. Such equipment often includes means for freezing and melting the residue. The temperature at which the residue melts and solidifies is such that substantially pure p,p-diarylphenol crystallizes and impurities accumulate in the resulting molten phase. An illustrative example of such equipment can be found in Modern Methods of Chemical Analysis (1968), pp. 15-16, the disclosure of which is incorporated herein by reference.

The following examples are used to further illustrate and facilitate the understanding of the present invention. All products obtained can be identified by conventional techniques including proton and carbon-13 NMR spectroscopy, infrared spectroscopy and X-ray techniques.

example

The accelerator-attached sulfonated polystyrene resin catalyst was prepared by mechanically stirring 7.5 parts (1.75% in water) of aminoethanethiol hydrochloride and 1 part of sulfonated polystyrene resin (Amberlite® ¹³¹ ) under nitrogen overpressure. about 4 hours to prepare. The resulting promoter-attached catalyst (about 20% of the sulfonic acid groups on the resin neutralized) was washed several times with water and dried under vacuum overnight at a temperature of about 80°C and a pressure of about 20 Torr.

To a reactor equipped with a pump, a reactant storage tank, a heatable reaction mass column capable of adding the ketone in stages, and a glass column with about 10 grams of catalyst attached to a promoter, a 36:1 molar ratio of phenol and Feed liquid of acetone. The direction of feed liquid movement is from the reactant storage tank to the heatable reactant material tower, and then to the glass tower. The glass tower (with upflow capability) was maintained at about 70°C. As the reaction proceeds, acetone is added in two stages with intermediate removal (distillation) of water until the water content of the residue is about 1000-1500 ppm. When additional acetone was added, the final molar ratio of phenol to acetone was 12:1.

Likewise, the resulting mixture containing p-, p-BPA (about 95%), ortho, p-BPA (about 3.5%) and chroman (about 0.30%) was vacuum distilled [pressure 4.5 torr (column kettle ), 2.7 torr (top), temperature 230°C (bottom), 210°C (top)] to remove phenol, o, p-BPA and chroman. The resulting residue (enriched in p,p-BPA) is fed to a zone refining unit for melt crystallization. The resulting final product, p-BPA, has a purity greater than 99.9%, indicating that a substantially pure product can be obtained without crystallization of the adduct and without a reaction recycle stream.

Claims (18)

1. one kind in the Crystallization Separation operation of not carrying out adducts with do not produce the method that is used to reclaim pure substantially right, right-diaryl phenol under the condition of reaction cycle logistics, and said method comprises the following steps:

(a) vacuum distilling is a kind of contains the mixture of right, right-diaryl phenol and obtains distillate and resistates; With

(b) resistates is carried out fusion-crystallization and obtains pure substantially right, right-diaryl phenol.

2.-diaryl phenol said right, right according to the process of claim 1 wherein has following general formula:

HO-A ¹-Yt-A ²-OH and A ¹And A ²Be to replace or unsubstituted divalent aryl independently of one another, Y is a bridging group, and the t value is 0 or 1.

3. according to the method for claim 2, wherein said right, right-diaryl phenol is 2,2-two (4-hydroxyphenyl) propane.

According to the process of claim 1 wherein said pure substantially right, right-diaryl phenol is about 90% purity at least.

According to the process of claim 1 wherein said pure substantially right, right-diaryl phenol is about 99% purity at least.

6. according to the process of claim 1 wherein that the said mixture that contains right, right-diaryl phenol is to obtain from the method that is used to prepare said right, right-diaryl phenol.

7. according to the method for claim 6, the wherein said method that is used to prepare said right, right-diaryl phenol is aryl phenol and the condensation reaction of ketone in the presence of promotor and acidic ion exchange resin catalyst.

8. according to the method for claim 7, wherein said acidic ion exchange resin catalyst is a sulfonated polystyrene.

9. according to the method for claim 7, wherein said promotor is a kind of 3-thiohydracrylic acid weighting agent.

10. according to the method for claim 7, wherein said promotor is attachable promotor, and is bonded on the said sulfonated polystyrene and the acidic-group that neutralizes and exist on it.

11., wherein all have in the acidic-groups on the sulfonated polystyrene not to be higher than 50% and to be neutralized according to the method for claim 10.

12. according to the method for claim 10, wherein said attachable promotor is C _1-4Amino-alkane mercaptan.

13. according to the method for claim 12, wherein said C _1-4Amino-alkane mercaptan is the 2-aminoothyl mercaptan.

14. according to the method for claim 7, wherein said aryl phenol is a phenol, and said ketone is acetone.

15. according to the process of claim 1 wherein that the said mixture that contains right, right-diaryl phenol also contains the neighbour, right-diaryl phenol, chroman and triaryl phenol.

16. according to the process of claim 1 wherein that vacuum distilling carries out not being higher than under about 300 backing pressure power.

17. according to the process of claim 1 wherein that said vacuum distilling carries out not being higher than under about 10 backing pressure power.

18. according to the process of claim 1 wherein that said fusion-crystallization finishes by zone melting or zone refining equipment.