JPS6237646B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing phenolic linear oligomers having a narrow molecular weight distribution. [Prior Art] Phenol resins are generally obtained by reacting phenols with formaldehydes under acidic or basic catalysts, and are widely used in industrial applications as thermosetting resins. However, the phenolic resin produced by the above-mentioned general manufacturing method contains unreacted components such as phenol monomer and 2
Alternatively, it is a mixture that contains low molecular weight components such as trinuclear bodies and also contains high molecular weight components with a molecular weight of several thousand. That is, it is a resin mixture with a wide molecular weight distribution. The proportions of each component with various molecular weights may vary due to slight differences in the amount of catalyst during production, fluctuations in reaction temperature, and uncertainties in end points such as emulsification point and gelation time, which can lead to variations in the proportions of components with various molecular weights. This will result in variations between lots. However, in recent years, it has become important for industrial materials to have stable properties without variations between production lots. Furthermore, in terms of physical properties, uniformity of physical property values is required for a variety of uses. There are two methods for producing phenolic linear oligomers with a narrow molecular weight distribution: a method of fractionating a conventional phenol resin with a wide molecular weight distribution by a separation operation, and a so-called sequential synthesis method in which one or several phenol nuclei are reacted one at a time. There is a method of obtaining the desired linear oligomer through several synthetic operations. [Problem to be solved by the invention] In the former method, phenolic resins having components with various molecular weights are separated based on the difference in molecular weight.
Although low molecular weight components and high molecular weight components are removed to obtain oligomers with a narrow molecular weight distribution, this is extremely difficult and no industrially suitable method has been found. Furthermore, in the latter sequential synthesis method, the synthesis operations are complicated, such as performing the synthesis operations several times and purifying each time. The present invention provides a method for producing phenolic linear oligomers with a narrow molecular weight distribution using relatively simple operations. [Means for solving the problem] The present invention solves the problem by (wherein, X is a methylene group -CH ₂ - or a dimethylene ether group -CH ₂ OCH ₂ -, at least 1
One is a dimethylene ether group. R is hydrogen or an alkyl group having 1 to 12 carbon atoms, and n is an integer of 3 to 8. ) is reacted with a phenol or alkylphenol without a catalyst or in the presence of a basic catalyst such as an alkali metal hydroxide or a Lewis acid catalyst such as anhydrous aluminum chloride to form a cyclic phenol []. This invention relates to a method for producing phenolic linear oligomers with a narrow molecular weight distribution using a ring-opening reaction. The cyclic phenol used in the present invention is, for example, described in J.Am.
Gutsche as shown in Chem.Soc. 103 3782 (81)
It can be obtained by the so-called one-step synthesis method. In this cyclic phenol,
At least one of the bonding groups between the phenol nuclei is
dimethylene ether group because it is cleaved in a later reaction.
CH ₂ OCH ₂ - must be. for example
The bishomoxa compounds named by Gutsche et al. are applicable to the present invention. Further, a p-substituted cyclic phenol can be converted into an unsubstituted cyclic phenol by the method of Bohmer et al. shown in Org.Prep.Proc.int. 10 113 (78). To cleave the dimethylene ether group of a cyclic phenol, it is possible to do so without a catalyst, but in that case, a long-term high-temperature reaction is required.
Basic catalysts such as sodium hydroxide and potassium hydroxide, anhydrous aluminum chloride, boron trifluoride,
Lewis acid catalysts such as tin chloride are used. The amount added is preferably 0.5 to 2.0 moles per mole of cyclic phenol. Furthermore, it is necessary to add phenol or alkylphenols as a reaction partner with the cleaved dimethylene ether bond. The amount added is 1.0 to 2.0 per mole of cyclic phenol.
Moles are preferred. Furthermore, the reaction temperature needs to be high in order to cleave the dimethylene ether group of the cyclic phenol, and is preferably 100 to 210°C. The reaction of the present invention can be carried out either in solution or in a molten state. However, when the reaction is carried out in a solution, a solvent with a boiling point of 100° C. or higher, such as toluene or xylene, is used to maintain the above reaction temperature. Further, when the reaction is carried out in a molten state, in order to make the reaction system uniform, it is preferable to homogenize or suspend the cyclic phenol and the phenol or phenols in an appropriate solvent before starting the reaction. [Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. Examples 1 to 4, Comparative Example 60 g of p-tert-butylphenol and 80% paraformaldehyde were placed in a four-necked flask equipped with a cooling tube, a water content receiver, a thermometer, and a stirring device.
Add 30g and 500ml of industrial xylene, and add 5N
Add 1 ml of potassium hydroxide aqueous solution and boil at reflux temperature for 4 hours.
Allowed time to react. The condensed water produced was collected in a water quantitative receiver. The precipitated solid content is filtered, the xylene solution is returned to the distillation flask, the xylene is concentrated under reduced pressure, and the xylene is further dried in vacuo to form a yellowish brown solid 44
I got g. This yellowish brown solid was recrystallized several times using a mixed solvent of methylene chloride and methanol to obtain 10 g of bishomoxa tetracycle. 2g of this cyclic phenol and phenol or p-
3 to 4 g of tert-butylphenol were once dissolved in acetone, and the solid obtained by removing acetone was reacted with sodium hydroxide or anhydrous aluminum chloride as a catalyst in an oil bath at 150° C. for 30 minutes. After the reaction, 50 ml of THF was added to remove THF-insoluble components. Table 1 shows the formulations, reaction conditions, and product amounts of Examples 1 to 4 and Comparative Examples.

〔Effect of the invention〕

According to the present invention, by synthesizing a cyclic phenol, purifying it, and subsequently performing a ring reaction between the cyclic phenols, there is no need for a special fractionation operation from a general phenolic resin having a wide molecular weight distribution,
Moreover, phenol linear oligomers with a narrow molecular weight distribution can be easily obtained without performing complicated synthetic operations as in the sequential synthesis method.

[Brief explanation of the drawing]

FIG. 1 is a chart showing the molecular weight distribution of the reaction products obtained in Examples 1, 2, 3, and 4 and Comparative Example.

Claims (1)

[Claims] 1 formula, (In the formula, X is a methylene group - CH ₂ - or a dimethylene ether group - CH ₂ OCH ₂ -, and at least one is a dimethylene ether group. , n is an integer of 3 to 8) and a phenol or alkylphenol are reacted without a catalyst or in the presence of a basic catalyst or a Lewis acid catalyst. A method for producing a shaped oligomer.