JPH03188036A - Method for producing parahydroxymethylphenols - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing para-hydroxymethyl phenols, and particularly to a method for producing para-hydroxymethyl phenols by reacting phenols and formaldehyde in an aqueous solvent under basic conditions. It is about the method.

Parahydroxymethylphenols are important compounds as raw materials for the synthesis of various organic compounds such as medicines, agricultural chemicals, and antioxidants, or parahydroxybenzaldehydes, and as resin modifiers.

[Prior Art 1] Generally, in a method of synthesizing hydroxymethylphenols by reacting phenol and formaldehyde over a base catalyst, the para/ortho ratio of the product is 1.0 or less. At present, there are many reports on the selective production of ortho-hydroxymethylphenols, but there are few reports on the selective production of para-hydroxymethylphenols, and no industrial production method has been established yet.

In the method of synthesizing hydroxymethylphenol from phenol, methods for increasing the production ratio of parahydroxymethylphenol include +1) a method of reacting phenol and aldehyde in the coexistence of polyalkylene ethers under a strong basic catalyst; 55-141423)+2) A method using an organic nitrogen compound having two or more nitrogen atoms in the molecule as a basic catalyst (JP-A-56-164)
34 Publication) etc. have been proposed. However, in these methods, the content of para-forms in mixed hydroxymethylphenol is 49% and 47%, respectively, and these methods cannot be said to be effective for producing para-forms.

Recently, compounds in which the seven hydroxyl hydrogens of cyclodextrin or schiflobukistrin are replaced with an average of about six hydroxypropyl or hydroxyethyl groups, or compounds in which the above compounds are crosslinked with hydroxypropenyl groups have been developed as catalysts. A highly selective method for synthesizing para-hydroxymethylphenols was disclosed (Japanese Unexamined Patent Publication No. 1106833). In this method, the para/ortho production ratio was improved to a maximum of 15.7 (94.0%).

[Problem to be Solved by the Invention 1 The purpose of the present invention is to propose a novel disaqueous methylation reaction of phenol, which is a further development of the above-mentioned method for synthesizing para-hydroxyphenol using a cyclodextrin catalyst [Problem to be solved] Means J The present invention provides highly selective para-hydroxymethylation using cyclodextrins, in which at least one of the primary hydroxyl groups of the cyclodextrin is substituted with the C-1 hydroxyl group of glucose or maltose. By using the compound as a catalyst, we succeeded in synthesizing parahydroxymethylphenols with higher selectivity than when using unmodified cyclodextrin as a catalyst.

That is, the present invention provides a method for producing parahydroxymethylphenols in which phenols and formaldehyde are reacted in an aqueous solvent under basic conditions, in which the primary hydroxyl group of cyclodextrin is replaced with C-1 of glucose or maltose.
This is a method for producing para-hydroxymethylphenols, characterized by using a cyclodextrin derivative substituted with hydrogen groups as a catalyst.

il+ Phenols Examples of phenols used as raw materials in the present invention include phenol, 2-substituted phenol, 3-substituted phenol, 3- and 5-position disubstituted phenol, and 2- and 5-position disubstituted phenol. Here, the substituents of the phenols include, for example, saturated and unsaturated hydrocarbon groups having carbon fi 1 to fi 6, an anol group, a hydroxyl group, a carboxyl group, a sulfone group, and a halogen.

(2) Formaldehyde As a formaldehyde source, formalin, paraformaldehyde, lower alcohol hemiformal, etc. can be used, but formalin is preferred.

(3) Base As the base, metal hydroxides such as sodium hydroxide and potassium hydroxide, metal hydrides such as sodium hydride, etc. can be used.

(4) Cyclodextrin derivatives Both α-1β-1 and γ-cyclodextrin can be used as the cyclodextrin.

A compound in which one of the primary hydroxyl groups of cyclodextrin is replaced with the C-1 hydroxyl group of maltose is synthesized by dehydrating and condensing the primary hydroxyl group of cyclodextrin and the C-1 hydroxyl group of maltose through an enzymatic reaction, Further, a dehydration condensation compound of the primary hydroxyl group of cyclodextrin and the C-hydroxyl group of glucose can be obtained as a hydrolyzate of the above-mentioned maltose substituted product.

These compounds are also available commercially, for example β
- The dehydration condensation compound of cyclodextrin and maltose is commercially available under the trade name Isoelite.The cyclodextrin compound used in the present invention becomes a homogeneous system during the reaction, but if the reaction system is made acidic after the reaction, the solubility decreases. The recovered cyclodextrin compound, which precipitates and can be easily recovered, can be reused as a catalyst.

In the present invention, one of the primary hydroxyl groups of cyclodextrin
In a reaction using a cyclodextrin compound, which is dehydrated and condensed with the C-1 hydroxyl group of glucose or maltose, as a catalyst, the para selectivity was 85 at a reaction temperature of 4°C.
It will be about %. When the reaction is carried out under the same conditions using a compound in which one of the primary hydroxyl hydrogens of cyclodextrin is substituted with a hydroxypropyl group as a catalyst, the para-selectivity is 80%. Thus, one of the effects of the present invention is that the selectivity of the paramethylolation reaction is improved compared to the conventional method by using a substituent for cyclodextrin.

The cypress reaction is carried out in a basic aqueous solution, and the amount of phenols is 0.1 to 1 mol, preferably 0.1 to 1 mol, preferably 0.1 to 1 mol, relative to the reaction solution Iff.
1 to 0.5 mol of O is used, and the cyclodextrin compound is used in an amount of equivalent to 50 times the amount of phenol, preferably 2 to 50 times the equivalent of phenol.
30 equivalents, and the base such as sodium hydroxide is not particularly limited as long as it is equal to or more than the equivalent of the sum of the cyclodextrin compound and the phenol. Furthermore, there is no limit to the amount of formaldehyde.

The reaction temperature is -5 to +100°C, preferably 0 to 60°C.
It is.

After the reaction is completed, the reaction solution is made neutral to acidic, the precipitated cyclodextrin compound is filtered off, and the product is recovered from the filtrate by distillation and purification.

[Example] Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 Into a 0.75N aqueous sodium hydroxide solution (1 mmol), 0.094 g of phenol (1 mmol) and one of the primary hydroxyl groups of β-cyclodextrin, β- was prepared by dehydrating and condensing the C- of maltose with the hydroxyl group. Dissolve 43.8 g (30 mmol) of cyclodextrin compound, then
Add 0.86 mA of wt% formaldehyde aqueous solution,
The reaction was carried out at 0°C for 24 hours.

The products are parahydroxymethylphenol and orthohydroxymethylphenol at 214, and the reaction yield is 214.
．． At 7 mol%, the selectivity for rose hydroxymethylphenol was 84.4%.

Example 2 As a cyclodextrin compound, a compound in which one of the primary groups of β-cyclodextrin was substituted with the C-1 hydroxyl group of glucose was used, and a reaction was carried out under the same conditions as in Example 1.

There are two types of products, rose hydroxymethyl phenol and ortho hydroxy methyl phenol, and the reaction yield is 2.4.
Mol%, selectivity of rose hydroxymethylphenol is 8
It was 3.9%.

Comparative Example 1 An unmodified β-cyclodextrin was used as a cyclodextrin compound, and the reaction was carried out under the same conditions as in Example 1.

The products were two types, parahydroxymethylphenol and orthohydroxymethylphenol, and the reaction yield was 25 mol%, but the selectivity for parahydroxymethylphenol was 75.0%.

Comparative Example 2 When the reaction was carried out under the same conditions as in Example 1 without adding a cyclodextrin compound, there were two products, hydroxymethylphenol and orthohydroxymethylphenol, but the reaction rate was 0.3. The selectivity for rose hydroxymethylphenol was 66.7%.

[Effect of the invention 1] The present invention provides a method for synthesizing para-hydroxymethylphenols from phenols, in which the primary hydroxyl group of cyclodextrin is replaced by C-1 of maltose or glucose.
By using a cyclodextrin compound substituted with a hydroxyl group as a catalyst and reacting it in a basic aqueous solution, parahydroxymethylphenol can be produced more selectively than when unmodified or hydroalkyl-substituted cyclodextrin is used. .

Claims (1)

[Claims] (1) In a method for producing parahydroxymethylphenols in which phenols and formaldehyde are reacted in an aqueous solvent under basic conditions, a cyclodextrin derivative in which the primary hydroxyl group of cyclodextrin is replaced with the C-1 hydrogen group of glucose or maltose is used. A method for producing parahydroxymethylphenols, characterized in that they are used as catalysts.