CS200351B1 - Process for preparing bisphenols - Google Patents

Description

The invention relates to a process for the preparation of bisphenols by condensation of phenols and ketones under cation exchange with a special polymeric material structure which ensures a high rate of condensation.

Strongly acidic cation exchangers are preferably used as catalysts for the preparation of bisphenols by condensation of phenols and ketones. For example, strongly acid cation exchangers are used according to U.S. Pat. Nos. 3,049,568, 3,394,089 and 3,760,006, mostly in the presence of promoters containing a mercapto group bound in various ways to an ion exchange resin. The type of ion exchange resin to be used as a catalyst is specified only as strongly acidic, with no particular regard to the nature of its polymer backbone. However, the choice of a certain type of polymer backbone is very important for the activity of the ion exchange catalyst in the bisphenol preparation process by the condensation of phenols and ketones. For example, Reinicker and Gates report that Dowex 50W X-4, a relatively low crosslinked cation exchange resin containing 4% divinylbenzene, is a good catalyst for the synthesis of 4,4- (1-methylidene) bisphenol from phenol and acetone. In contrast, the above crosslinked ion exchanger of the same type Dowex 50W X-8, containing 8% divinylbenzene, was catalytically inactive for this reaction. Thus, it is seen that an important property of the polymer backbone of ion exchange catalysts for the preparation of bisphenols is low crosslinking. Low cross-linked ion exchangers swell considerably, and this allows a sufficiently rapid transport of reactants and products between the active groups and the surface of the ion exchange particles. This is particularly important when larger-sized molecules are involved, as is the case with bisphenol synthesis. Due to large volume changes between the swollen state and the swollen state in the reaction pro2001

200 351 centers cause mechanical stresses and cracking of ion exchange particles. The easy deformability of the ion exchange particles together with changes in its granulometric composition may result in an increase in the pressure drop across the catalyst bed, possibly even its complete clogging.

It would appear that these problems can be solved by the use of so-called macroreticular ion exchangers as a catalyst in which contact with the active groups within the ion exchange grains is facilitated by the porous structure of their half-dimensional skeleton. These ion exchangers have a fairly high degree of crosslinking, and the divinylbenzene content of commercially available ion exchangers of this type is 15 to 25%. Such a rigid polymer backbone is needed to maintain the porous structure even after the introduction of the active groups. However, it can be calculated by calculating that the pores of commercial macroreticular ion exchangers

specific surface areas of 20 to 50 m / g provide up to about 2 to 5% of the active groups directly.

Access to others is possible through the swelling of the polymer mass. It will be shown by examples that these ion exchangers are not the most suitable bisphenol synthesis catalysts.

SUMMARY OF THE INVENTION The present invention provides a process for preparing bisphenols by condensation of phenols with ketones, wherein the condensation is carried out in the presence of an ion exchange catalyst whose polymeric skeleton is a styrene-divinylbenzene copolymer with optional ethylvinylbenzene. of the ion exchange catalyst by the addition of solvents of the C 5 -C 13 aliphatic hydrocarbon type, the C 15 -C 20 fatty acids, the C 6 -C 9 aromatic hydrocarbons, the C 1 -C 4 aliphatic halogenated hydrocarbons and the halogenated benzene derivatives or mixtures thereof and / or by the addition of chain transfer agents such as carbon tetrachloride or C 4 -C 14 alkyl mercaptan, which may be added to the polymerization mixture at the beginning or during the polymerization.

It is known that in the copolymerization of styrene and divinylbenzene, due to the higher polymerization rate of divinylbenzene, a polymer with higher crosslinking than at its end is formed at the beginning of the reaction (British Pat. 1,292,226). However, this effect is largely obscured by the intergrowth of polymer coils when preparing conventional ion exchange resins. However, by adding suitable solvents to the polymerization mixture, the individual polymer coils can be separated from each other as they grow. Solvents which are miscible with monomers but in which the polymer formed does not swell, for example aliphatic hydrocarbons or fatty acids, are suitable for this purpose.

The permeability of the polymer backbone can be further increased by preventing interweaving of the polymer chains during their growth. For this purpose, it is appropriate to add to the polymerization mixture solvents in which the resulting polymer swells, for example aromatic or halogenated hydrocarbons or other suitable solvents. These additives solvate the growing polymer chains, separate them from each other and thus prevent their interweaving.

A third possibility of favorably affecting the polymer structure of the ion exchange catalyst for bisphenol synthesis is to use a phenomenon known in macromolecular chemistry as a chain transfer effect. This is called the effect of certain additives in the polymerization mixture, such as carbon tetrachloride or mercaptans, which stop the development of an already growing chain and at the same time initiate the start of growth of a new chain. This results in an increase in the occurrence of shorter polymer chains growing 2e of the basic polymer backbone in which growth was interrupted before

200,351, the free end could be incorporated into another polymer chain. The additives causing this effect can be added to the polymerization mixture at the beginning or also during the copolymerization.

All of the above-described methods for affecting the polymer structure of the ion exchange bisphenol synthesis catalyst can be used alone or in various combinations.

In the proposed process for the synthesis of bisphenols with an ion exchange catalyst having an optimized polymer backbone structure, it is desirable to take advantage of the aforementioned beneficial effect of sulfur compound additives whether already dissolved in the reaction mixture or bound appropriately to the ion exchange catalyst.

Below are examples of synthesis of bisphenols of ocrtia of this process using ion exchange catalysts with optimized structure of the polymer backbone and, for comparison, using conventional commercial ion exchange types.

Examples

Polymer skeleton samples were prepared according to the conventional suspension polymerization procedure based on the following compositions of the basic polymerization mixtures:

(a) 85,6 g of styrene, 16,8 g of divinyllbenzene (61,5% of active ingredient) and 78,5 g of technical naphtha of the boiling point 80 to 95 ° C

(b) 169 g of styrene, 15 g of divinyllbenzene (61,7 ϊ), 140 g of the gasoline fraction boiling at 150 to 175 ° C and 76 g of toluene

c) 194.7 g styrene, 21.3 g divinyllbenzene (61.7%), 60 g stearin and 24 g toluene

(d) 89 g of styrene, 8,5 g of divinyllbenzene (61,7%), 25 g of the gasoline fraction boiling at 70 to 110 ° C and 10 g of carbon tetrachloride.

After removal of the inert components and drying, all polymers were swelled with dichloroethane and sulfonated with sulfuric acid. The resulting cation exchangers had an exchange capacity of 4.97 to 5.20 mval / g.

The synthesis of one of the bisphenols, Diana, phenol and acetone was carried out in a laboratory flow reactor at 70 ° C. A mixture of phenol and acetone in a molar ratio of 8: 1 with 0.5% wt. etvlmerkaptanu. The analysis of the output mixture was performed by high performance liquid chromatography and the results were expressed as percent acetone conversion. The results are shown in the table.

TABLE

Comparison of the results of dianu synthesis using different ion exchange catalysts.

70 ° C, phenol: acetone molar ratio 8: 1, 0.5 wt. ethylmercaptan Catalyst Catalyst load g reaction mixture / g cat.h Acetone conversion % Sample (a) 8 34 4,5 39 2.5 51 Sample b) 9.4 54 4.4 65 3.7 75 Sample c) 8 42

200 351

4,5 2.7 46.5 54 Sample d) 9.6 58 5.6 61 Wofatit Y-37 8.7 22nd 4.4 25 2.7 33 Amberlyst 15 9.6 24 4.9 45 Ostion KS 8.6 29 4.4 40 3.2 48

All ion exchangers tested had about the same catalyst bed volume in the reaction medium.

Comparing the values shown in the table, it can be seen that in the bisphenol synthesis carried out according to the invention using catalysts with optimized structure of the polymer backbone (samples a to d), significantly higher conversions can be achieved under otherwise identical conditions than using commercial catalysts as macroreticular -37, Amberlyst 15), and the standard type (Ostion KS).

Claims (1)

Process for the preparation of bisphenols by condensation of phenols with ketones, characterized in that the condensation is carried out in the presence of an ion exchange catalyst whose polymeric skeleton consists of a copolymer of styrene with dlvinylbenzene, optionally admixed with ethylvinylbenzene. catalyst by adding solvents of the C 5 -C 13 aliphatic hydrocarbon type, C 15 -C 20 fatty acids, C 6 -C 9 aromatic hydrocarbons, C 1 -C 4 aliphatic halogenated hydrocarbons and halogenated benzene derivatives or mixtures thereof and / or by adding chain transfer agents such as carbon tetrachloride or C 4 -C 14 alkyl mercaptans, which can be added to the polymerization mixture at the beginning or during the polymerization.