DE1643552B2 - PROCESS FOR PRODUCING P-PHENYLPHENOL - Google Patents

Description

The invention relates to the production of p-phenylphenoJ by dehydration of p-cyclohexenylpheno).

Although many different types of phenols have been proposed for making phenolic resins and were used, p-phenylphenol is of particular importance in the manufacture of phenolic resins found in coating formulations, e.g. B. of paints and adhesives should be used. Therefore, the demand for this phenol has increased so that the present has become scarce The invention now relates to a method for dehydrating a readily available and easily prepared Starting material for the formation of the desired phenol. In addition, the method according to the invention easily incorporate into a relatively simple, known process for the preparation of p-cyclohexenylphenol, wherein a combined or simultaneous work becomes possible. They also become valuable by-products obtain.

A process for the production of p-phenylphenol has been found which is characterized by is that you can p-Cyclohexenylphenol by heating in the liquid phase with an excess of a hydrogen acceptor in the presence of a palladium, nickel or platinum catalyst to a temperature of about 100 to 200 ° C dehydrated.

The dehydrogenation product can then, if appropriate, by fractional distillation or recrystallization purified to form pure p-phenylphenol. The excess hydrogen acceptor and its hydrogenated product can be separated or otherwise used.

Various compounds were used as hydrogen acceptors in the process according to the invention Used success. Such hydrogen acceptors are organic compounds with ethylenically unsaturated Bonds such as ethylene, propylene; organic compounds with acetylenically unsaturated bonds, such as Acetylene, propyne; organic compounds with azo groups, such as azobenzene, as well as nitro and carbonyl compounds. Organic compounds with conjugated compounds are particularly effective hydrogen acceptors Double bonds, such as a-methylstyrene, nitrobenzene, p-nitrophenol, p-chloronitrobenzene, maleic anhydride, Methyl acetylene, indene, crotonic acid, sorbic acid. Of these hydrogen acceptors, Λ-methylstyrene, p-Nitrophenol and p-Chloronitrobenzene are preferred because their such uses are exceptional provides valuable by-products, d. H. Cumene, p-aminophenol, and p-chloroaniline, which convert easily into p-aminophenol is transformed.

552 The most preferred acid acceptor is Λ-methylstyrene, since in this compound all reactants and products are at the reaction temperature are soluble; on cooling to room temperature, the p-phenylphenol product becomes insoluble and separates in high purity from the reaction solution.

As indicated above, the process according to the invention is suitable for the dehydrogenation of p-cyclohexenylphenol particularly for use in combination with the process for preparing p-cyclohexenylphenol from phenol and cyclohexanone. This process and the dehydration point can be represented by the following reaction scheme:

1. Condensation reaction

2. Cleavage reaction

OH

1
Base or weak acid //

3. Dehydration

HO

Pd

Ηο- / ν / Λ

Briefly, the condensation reaction (!) From the reaction of cyclohexanone with an excess of phenol at a temperature of 6O ⁰ C etwo in the presence of a Kondensationskatalysator'-of hydrochloric acid and ethylmercaptan as an accelerator.

This condensation reaction is usually complete after about 1 to 3 hours at 60 ° C.

When the condensation has ended, the catalysts and water are removed. This is done appropriately by distillation, although other conventional methods can be used if desired. That l, l-bis (p-hydroxyphenyl) cyclohexane adduct can

6c expediently by centrifuging the excess Phenol are separated, although here again other, customary separation agents are used can be.

In the cleavage reaction, the 1,1-bis (4-hydroxyphenyl) cyclohexane is cleaved by heating to a preferred temperature of about 180 to 200 ^° C. in the presence of a basic or acidic cleavage catalyst.

The cleavage products, phenol and p-cyclohexenylphenol, are then heated ^{to a temperature of about 100 to 200 °} C. with an excess of a hydrogen acceptor in the presence of the catalyst

The dehydrogenation product can then be effectively converted into p-phenylphenol and the by fractional distillation hydrogenated by-product that can be separated can be decomposed.

It har. A combination of the dehydrogenation process according to the invention has proven to be particularly advantageous with the p-cyclohexenylphenol process represented by the reaction steps (1) and (2). Steps (2) and (3) can be combined and carried out at the same time as the only step, thereby of course reducing the overall time of the procedure and increasing its effectiveness will.

The following examples illustrate the present invention.

example 1

^{423 g (2.43 mol) of p-cyclohexenylphenol were heated to 150 °} C. for 8 hours on pulverized animal charcoal with 2498 g of α-methylstyrene and 168 g of 5% palladium. The catalyst was filtered off from the hot reaction mixture, the filtrate was vacuum distilled at 100 torr, with 776 g of a Cumo! enriched fraction were removed. The residue was cooled to room temperature to crystallize out 275 g of wet crystals. The crystals were dried to a constant weight to give 245 g of pure p-phenylphenol (F. 163.8 to 165.0 ⁰ C), corresponding to a yield of 49%.

Example 2

^{539 (ξ p-cyclohexenylphenol were heated to 150 °} C. for 6 hours with 1650 g of the cumene-enriched -methylstyrene fraction from Example 1 and 1560 g of new o-methylstyrene, using the same catalyst mixture as in Example 1. The reaction mixture was used for recovery The filtrate was vacuum distilled to remove 1175 g of cumene-enriched distillate. The residue was cooled to room temperature to crystallize p-phenylphenol. The crystals were filtered, washed with cumene and dried to give 372 g of p-phenylphenol (F. 164.8 to 165.0 ° C.), which corresponded to a yield of 74.2%.

Example 3

ίο 174 g (1.0 mol) of p-Cyclohexenylphenol and 615 g (5.0 mol) of p-nitrobenzene were heated for 8 hours with 50 g of 5% palladium on powdered charcoal to 150 to 18O ⁰ C. The mixture was filtered to remove the catalyst. The filtrate was distilled to give an aniline-nitrobenzene fraction and 136 g of p-phenylphenol in 80% yield.

Example 4

940 g of phenol and 98 g of cyclohexanone was heated for 3 hours at 70 ⁰ C in the presence of 4.7 g of anhydrous hydrogen chloride and 2.0 g of ethylmercaptan. The reaction mixture was distilled under reduced pressure to remove the hydrochloric acid, the water of reaction and ethyl mercaptan. The adduct of bisphenol (II-bis - ^ - hydroxyphenyn-cyclohexane) and phenol was filtered off from the reaction mixture and washed with phenol. Thus 440 g of crystals containing 260 g of bisphenol were obtained.

^{The crystals were heated to 180 °} C. for 3 hours with 0.27 g of sodium hydroxide under a nitrogen atmosphere. The reaction mixture was distilled under reduced pressure to yield a fraction consisting essentially of phenol and 157 g of p-cyclohexenylphenol.

The cyclohexenylphenol was with 1060 g Λ-methylstyrene and 60 g of 5% palladium catalyst heated on powdered animal charcoal. The reaction mixture wui de refluxed at atmospheric pressure for 6 hours and removed the catalyst filtered hot. The filtrate was distilled to remove a fraction enriched in cumene and used for The product crystallized and cooled to room temperature. By filtering the mother liquor 77 g of pure p-phenylphenol were obtained. Analysis by vapor phase chromatography showed that a similar amount of p-phenylphenol remained dissolved in the mother liquor, which by recycling in the procedure can be won.

Claims (2)

1643 2 claims: 1. Process for the production of p-phenylphenol, characterized in that p-Cyclohexenylphenol by heating in the liquid phase with an excess of a hydrogen acceptor in the presence of a palladium, nickel or platinum catalyst to a temperature of about 100 to 200 ° C 2. The method according to claim 1, characterized in that that a-methylstyrene or p-nitrophenol is used as the hydrogen acceptor