JPH06340565A - Production of 4,4'-dihydroxydiphenylmethane - Google Patents

Abstract

PURPOSE:To provide a production method in which formaldehyde and phenol are reacted in the presence of an acidic catalyst and a urea resin, and the urea resin is easily separated after the reaction and recycled, and by which the subject compound is obtained in high selectively and yield. CONSTITUTION:In a flask, 41% formalin aqueous solution and 0.1N sodium hydroxide aqueous solution are placed, heated at 95 deg.C under stirring, a urea aqueous solution is added thereto, the reaction is continued for 30min at this temperature, pH is adjusted at 8.0 after the cooling to the room temperature, the reactional product is condensed under a reduced pressure of 5mmHg to obtain a colorless and transparent aqueous solution of a urea resin. Then, the aqueous solution of the urea resin is placed together with phenol and oxalic acid in a flask, the mixture is heated at 75 deg.C under stirring, a 41% formalin aqueous solution is added dropwise and the reaction is continued at 80 deg.C for 6hr to complete the reaction. Water and excess phenol is removed by distillation under reduced pressure of 10mmHg, the urea resin is removed by filtration and the object compound is obtained in high selectivity for 4,4'-isomer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a polymer raw material monomer such as epoxy resin from phenol and formaldehyde.
And a method for selectively producing 4,4'-dihydroxydiphenylmethane.

[0002]

Dihydroxymethane is obtained by heating formaldehyde and excess phenol in the presence of various acids, usually the reaction product of which is
It is a mixture of three isomers of 2'-form, 2,4'-form and 4,4'-form, and the isomer ratio is such that the 2,2'-form is 15 to 25%, 2,4'-form. '-40-45% of body, 4,4'
-Body was in the range of 30-40%, and the production ratio of 4,4'-body was not always satisfactory.

Therefore, as a method for selectively synthesizing the 4,4'-form, for example, in JP-B-49-6310, a reaction is carried out in the presence of an alkyl-substituted urea.
Japanese Examined Patent Publication (Kokoku) No. 48-38694 discloses a method of carrying out the reaction in the presence of a polar aprotic solvent.

[0004]

However, although the method of adding an alkyl-substituted urea can achieve an excellent selectivity of 4,4'-form, it is possible to wash with water when the urea compound is separated from the product after the reaction is completed. Since it is necessary, it not only complicates the work but also lowers the yield, and there is a problem that the alkyl-substituted urea once used cannot be regenerated and used as a catalyst.

On the other hand, in the method of carrying out using a polar aprotic solvent as a catalyst, it is possible to recover the catalyst after the reaction and reuse it, but again, a washing step is required and the work becomes complicated. However, there was a problem that the recovery rate was not sufficient and the selectivity of 4,4′-form was also lowered.

The problem to be solved by the present invention is that in the production of dihydroxydiphenylmethane, the selectivity of 4,4'-form is extremely high, the catalyst can be easily separated from the reaction product, and the separated catalyst Another object of the present invention is to provide a method for producing 4,4′-dihydroxydiphenylmethane, which enables reuse of

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the above problems can be solved by reacting formaldehyde and phenol in the presence of an acidic catalyst and a urea resin. They have found the present invention and completed the present invention.

That is, the present invention relates to a method for producing 4,4'-dihydroxydiphenylmethane, which comprises reacting formaldehyde and phenol in the presence of an acidic catalyst and a urea resin.

The urea resin used in the present invention is not limited, and is obtained, for example, by reacting urea with formaldehyde in the presence of an alkali catalyst. Here, as ureas, unsubstituted urea, monosubstituted urea such as monomethylurea, monophenylurea, N, N′-
Disubstituted urea such as dimethylurea and N, N′-diphenylurea may be mentioned, but unsubstituted urea is particularly preferable in view of high selectivity of 4,4′-form during production of dihydroxydiphenylmethane.

The formaldehyde used in the production of the urea resin is not particularly specified as to its use form, but it is a 10-70% aqueous solution of formaldehyde and a polymer having a degree of polymerization of formaldehyde of 3-100. Moreover, any of paraformaldehyde which can be easily dissolved in water to form formaldehyde or a mixture thereof may be used, but it is preferably used as a 10 to 70% aqueous solution of formaldehyde from the viewpoint of easy handling.

The reaction molar ratio between ureas and formaldehyde is not particularly limited, but it is preferable that the ureas and formaldehyde react with each other in a molar ratio of 1: 1 in order to increase the activity thereof, and therefore, It is preferable that the charge ratio is 0.5 to 1.5 mol of formaldehyde with respect to 1 mol of urea.

The alkali used as a catalyst in the production of the urea resin is not particularly limited, but alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide. And amines such as triethylamine and pyridine.

A solvent is usually used in the production of the water-soluble urea resin, and it is not particularly limited as long as it is an inactive compound as a reaction raw material, and examples thereof include water, methanol, ethanol and the like. Water is especially preferred.

The method for producing the urea resin is not particularly limited. For example, a predetermined amount of formaldehyde aqueous solution is added with an alkali and heated to 60 to 100 ° C., and then a predetermined amount of the urea resin is dissolved in a solvent. One is continuously or intermittently added to the reaction system, and then 0.5 to
After stirring for 3 hours, the mixture was cooled to room temperature, and then an alkali was added to adjust the pH value to 8-12, preferably 9-1.
The target urea resin can be obtained by adjusting the range to 0.

The resulting urea resin may be used as a catalyst for producing dihydroxydiphenylmethane after isolation and purification, or may be used in the state of an aqueous solution. The structure of the urea resin thus obtained is not particularly limited, but the methylene group attributed to formaldehyde is a urea compound because of its extremely excellent selectivity for 4,4′-form. It preferably has a structure that serves as a linking group for the nitrogen atom therein, and more preferably has a cyclic structure. Although the molecular weight of the urea resin is not particularly limited, it is usually preferably 300 to 1000.

The method for producing 4,4'-dihydroxydiphenylmethane of the present invention comprises reacting formaldehyde and phenol in the presence of an acidic catalyst and the urea resin obtained as described above.

The form of the formaldehyde used herein is not limited to any particular form, and is 10 to 70% of the formaldehyde as in the case of urea resin production.
It may be either an aqueous solution, paraformaldehyde which is a polymer of formaldehyde having a degree of polymerization of 3 to 100, or a mixture thereof.

Examples of the acidic catalyst include inorganic acids such as hydrochloric acid and sulfuric acid, organic acids such as formic acid, oxalic acid and paratoluenesulfonic acid, cation exchange resins, acidic clay and various acidic substances such as boron trifluoride. Of these, oxalic acid is preferable because it can be easily treated in the purification step.

The reaction molar ratio of the raw materials used in the present invention is usually in the excess of phenol relative to formaldehyde, specifically, to 1 mol of formaldehyde.
It is in the range of 1 to 50 mol, preferably 5 to 30 mol of phenol.

The urea resin used in the present invention may be an isolated solid or an aqueous solution. The amount used is not particularly limited, but formaldehyde 1
The amount is preferably 10 to 1000 g, and more preferably 30 to 200 g, in terms of excellent selectivity improving effect.

The specific method of the reaction is not particularly limited, but, for example, after a predetermined amount of phenol, an acidic catalyst and an aqueous solution of urea resin are charged in a reaction vessel, 30 to 30
Heating to 150 ° C., preferably 50-100 ° C.,
Then, a method of adding a predetermined amount of formalin as an aqueous solution continuously or intermittently can be mentioned. The reaction time depends on the reaction temperature and the amount of the acidic substance of the catalyst, but is usually preferably in the range of 3 to 10 hours.

After completion of the reaction, water and excess phenol are distilled off, and the precipitated urea resin is filtered to obtain the desired product dihydroxydiphenylmethane. further,
If desired, the obtained dihydroxydiphenylmethane can be purified by a method such as distillation and recrystallization to obtain pure 4,4′-dihydroxydiphenylmethane.

The recovered urea resin can be repeatedly used as a catalyst for producing dihydroxydiphenylmethane.

[0024]

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Reference Example 1 (Manufacturing Method of Water-Soluble Urea Resin) A 41% formalin aqueous solution 50.
0 g (0.60 mol) and 75 ml of a 0.1 N aqueous sodium hydroxide solution were added, and the mixture was heated and stirred at 95 ° C. A solution prepared by dissolving 50.0 g (0.83 mol) of urea in 50 ml of water was added dropwise to this solution over 1 hour. After completion of dropping, 30
Continue to stir at 95 ° C for min and then cool to room temperature,
The pH was adjusted to 8.0 with regular aqueous sodium hydroxide solution. Then, the aqueous solution obtained under reduced pressure of 5 mmHg was concentrated to obtain 116.0 g of a colorless and transparent urea resin aqueous solution. The urea resin concentration is 60.8% by weight.

Example 1 150.1 g (1.59 mol) of phenol, 6 oxalic acid
3 mg (0.70 mmol) and urea resin aqueous solution 5.
0 g (including 3.04 g of resin) was placed in a 300 ml flask, heated to 75 ° C. with stirring, and 3.85 g (0.053 mol) of a 41% formalin aqueous solution was added dropwise over 10 minutes. Then, stirring was continued at 80 ° C. for 6 hours to complete the reaction. After completion of the reaction, water and excess phenol were distilled off under reduced pressure of 10 mmHg, and the urea resin was filtered to obtain 10.4 g (98%) of dihydroxydiphenylmethane. As a result of analyzing the product by gas chromatography,
The ratio of isomers is 5.6% for 2,2'-form and 2,4'-form.
The body was 18.8% and the 4,4′-body was 75.6%.
Further, the yield of the obtained 4,4′-form was 74.1%.

Example 2 An experiment was conducted in the same manner as in Example 1 except that 5.0 g of an aqueous solution of 3.04 g of the recovered urea resin used in Example 1 was used in place of the newly prepared aqueous solution of urea resin. . As a result, 10.4 g of dihydroxydiphenylmethane (98
%), And the ratio of isomers by gas chromatography was 5.8% for 2,2′-form and 19.9 for 2,4′-form.
%, 4,4′-form was 74.3%. In addition, the yield of the obtained 4,4′-form was 72.8%.

Comparative Example 1 Phenol 141.2 g (1.
50 mol), 18.7 g (0.25 mol) of monomethyl urea and 15.3 (0.15 mol) of 35% agricultural hydrochloric acid,
Heated to 45 ° C. with stirring, 41% formalin aqueous solution 18.
3 g (0.25 mol) was added dropwise over 10 minutes. Then, stirring was continued at 45 ° C. for 15 hours.

After completion of the reaction, the mixture was neutralized with sodium hydrogen carbonate and filtered, and then water and excess phenol were distilled off under reduced pressure of 10 mmHg to obtain 44.0 g (88%) of dihydroxydiphenylmethane.

As a result of analyzing the product by gas chromatography, the ratio of isomers was 3.6% in the 2,2'-form,
2,4'-body is 21.8%, 4,4'-body is 72.6%
Met. The yield of the obtained 4,4′-form was 63.
It was 8%.

Comparative Example 2 141.2 g of phenol (1.
50 mol), 141.2 g of dimethylformamide (1.
(93 mol) and 35% agricultural hydrochloric acid 19.6 (0.11 mol) were added, the mixture was heated to 65 ° C. with stirring, and 41% formalin aqueous solution 81.2 g (0.25 mol) was added dropwise over 10 minutes.
Then, stirring was continued at 65 ° C. for 15 hours.

After completion of the reaction, the mixture was neutralized with sodium hydrogen carbonate and filtered, and then water, dimethylformamide and excess phenol were distilled off under reduced pressure of 10 mmHg to obtain 36.0 g (72%) of dihydroxydiphenylmethane. It was

As a result of analyzing the product by gas chromatography, the ratio of isomers was 4.2% in the 2,2'-form,
2,4'-body 29.9%, 4,4'-body 65.9%
Met. Further, the yield of the obtained 4,4′-form was 47.
It was 4%.

[0034]

EFFECTS OF THE INVENTION According to the present invention, the selectivity of 4,4'-form is extremely high, the catalyst can be easily separated from the reaction product, and the separated catalyst can be reused. Also,
Since the purification becomes easy, the yield of the desired product also improves.

Claims (5)

[Claims] 1. A method for producing 4,4′-dihydroxydiphenylmethane, which comprises reacting formaldehyde and phenol in the presence of an acidic catalyst and a urea resin. 2. The method according to claim 1, wherein the water-soluble urea resin is obtained by reacting urea with formaldehyde in the presence of an alkali catalyst. 3. The method according to claim 2, wherein the urea is urea. 4. After completion of the reaction, unreacted phenol and water are distilled off, and then the water-soluble urea resin is filtered off.
The manufacturing method according to 2 or 3. 5. A urea resin obtained by filtration according to the method of claim 4, wherein the reaction between formaldehyde and phenol is carried out again in the presence of the urea resin and an acidic catalyst. And a method for producing 4,4′-dihydroxydiphenylmethane.