JPH0231073B2 - OKISHIFURABANKAGOBUTSUNOSEIZOHO - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention provides polyalkyl-2-(2,4-dihydroxyphenyl)-7-hydroxychroman (hereinafter referred to as oxyflavan) by reacting an aliphatic ketone with resorcinol. related to the method of manufacturing. [Industrial Application Fields] Oxyflavan is an industrially useful compound that is in demand as an intermediate for agricultural chemicals such as insecticides and herbicides, or as a manufacturing intermediate for monomer components of copolymers for resin modification. It is. [Prior Art] Conventional methods for producing oxyflavans include, for example, JP-A-55-139375 and British Patent No. 822659, in which an aliphatic ketone and resorcin are reacted in the presence of an inorganic acid using water as a solvent. The method and the amount of resorcinol to be charged to the aliphatic ketone are expressed in molar ratios, and a method has been proposed in which the reaction is carried out at a high molar ratio of 3 or more in the former case and a low molar ratio of 0.5 to 1.0 in the latter case. However, in this method, when the reaction is carried out under conditions of a low molar ratio,
Since side reactions such as high condensation and the formation of isomers are likely to occur, there are drawbacks such as low selectivity and yield of the target product and slow reaction rate. On the other hand, a method in which the reaction is carried out at a high molar ratio in which resorcinol is in excess has drawbacks such as being disadvantageous in terms of cost. [Object of the Invention] The present inventors have recognized that conventionally known methods for producing oxyflavans have such drawbacks, and have conducted extensive studies to improve them. [Structure of the Invention] As a result, if the following method is adopted, the yield of the target product can be improved in a shorter reaction time than the conventional method,
Moreover, they discovered that it was possible to obtain a product with high purity, and completed the present invention. That is, according to the present invention, polyalkyl-2-(2,4
Provided is a method for producing -dihydroxyphenyl)-7-hydroxychroman, characterized in that the reaction is carried out in the presence of an acidic catalyst and a neutral salt. In the method of the present invention, examples of aliphatic ketones used as raw materials include acetone, methyl ethyl ketone, diethyl ketone, ethyl propyl ketone, and dipropyl ketone, and among these, it is preferable to use acetone.
The amount of the aliphatic ketone used is generally 1 mol or less, preferably 0.7 mol or less, per 1 mol of resorcinol. In the method of the present invention, by reacting the aliphatic ketone and resorcinol in the presence of an acidic catalyst and a neutral salt, the general formula [] (In the formula, R ¹ and R ² each have an arbitrary carbon number of 1
represents a primary alkyl group having 1 to 3 carbon atoms, R ³ is hydrogen or an alkyl group having 1 to 2 carbon atoms, and
A polyalkyl-2-(2,4-dihydroxyphenyl)-7-hydroxychroman represented by R ² (representing an alkyl group having fewer carbon atoms than R 2 ) is obtained. Specifically, the acidic catalyst includes sulfuric acid, hydrochloric acid,
Examples include phosphoric acid, benzenesulfonic acid, toluenesulfonic acid, and cation exchange resins, among which it is preferable to use sulfuric acid and hydrochloric acid, particularly hydrochloric acid. The amount of the acidic catalyst used is 0.05 to 1 equivalent per mole of resorcin, preferably
0.1 to 0.5 equivalent. In the method of the present invention, the reaction is usually carried out in the presence of water, and in this case it is preferable to use an aqueous solution in which the acidic catalyst is dissolved at a concentration of 5 to 10% by weight relative to water. The amount of the aqueous solution used is usually 6 parts by weight, preferably 4 parts by weight or less, per 1 part by weight of resorcinol. Specifically, the neutral salts used in the method of the present invention include alkali metal hydrochlorides such as sodium chloride and potassium chloride, and sodium sulfate;
Examples include alkali metal sulfates such as potassium sulfate, among which it is particularly preferable to use sodium chloride and potassium chloride. The amount of the neutral salt to be used is usually such that the neutral salt is dissolved in the amount necessary to saturate the reaction solution.
In the present invention, the concentration of the neutral salt does not necessarily have to be saturated, and can be used as appropriate within the range from about 1/5 of the saturated concentration to the saturated concentration. Oxyflavans obtained by the method of the present invention are polyalkyl-2-(2,4-dihydroxyphenyl)-7- corresponding to the aliphatic ketone used.
Hydroxychroman, specifically 2, 4,
4-trimethyl-2-(2,4-dihydroxyphenyl)-7-hydroxychroman, 2,4,4
-triethyl-3-methyl-2-(2,4-dihydroxyphenyl)-7-hydroxychroman,
2,4,4-tri-n-propyl-3-ethyl-
An example of this is 2-(2,4-dihydroxyphenyl)-7-hydroxychroman;
It is particularly suitable for producing 4,4-trimethyl-2-(2,4-dihydroxyphenyl)-7-hydroxychroman. The reaction in the method of the present invention is preferably carried out using a method in which an aliphatic ketone is continuously or intermittently supplied to a mixture consisting of resorcinol, an acidic catalyst, a neutral salt, and water. In this case, the feed rate of the aliphatic ketone is usually 0.6 equivalent/hr or less, preferably 0.4 equivalent/hr, per mole of resorcinol as the raw material. If the feeding rate is too fast, the formation of by-products will be promoted, and the purity and yield of the oxyflavan compound will tend to decrease.
The reaction temperature varies depending on the aliphatic ketone and acidic catalyst used, but is usually 20 to 80°C, preferably
The temperature is between 40 and 70°C. In the method of the present invention, after the aliphatic ketone has been introduced, the reaction mixture is further maintained at a predetermined temperature. This holding time varies depending on the reaction conditions such as the aliphatic ketone used as the raw material, the reaction temperature, and the catalyst, but is usually about 2 to 8 hours. Any amount of neutral salt can be used as long as the neutral temperature concentration in the reaction solution is within the range of about 1/5 of the saturation concentration to about 1/5 of the saturation concentration. The reaction is usually carried out under atmospheric pressure, but can also be carried out under appropriate pressure if necessary. After the reaction is completed, the resulting slurry reaction mixture is neutralized by adding an alkali such as sodium hydroxide or potassium hydroxide. As the alkali used at this time, it is preferable to use an alkali such that the salt produced by the neutralization treatment becomes the same neutral salt as that used in carrying out the reaction of the present invention. The neutralized product is divided into a solution and a solid based on the solid-liquid fraction such as temperature. Since the solid substance contains salt, it is washed with an appropriate amount of water to remove the salt, and then dried to obtain the desired product, oxyflavan, in the form of a white powder. On the other hand, although the solution separated from the reaction mixture contains neutral salts, unreacted resorcinol, aliphatic ketones, etc., the amount of aliphatic ketones is usually small. The solution can be recycled and reused in the reaction system as necessary. When recycling and reusing, an appropriate amount of the solution is blown, and then the concentrations of resorcinol, acidic catalyst, and neutral salt in the solution are adjusted to satisfy the above conditions, and then a predetermined amount of the solution is blown. A reaction with an aliphatic ketone is carried out. [Effects of the Invention] When the method of the present invention is applied to the production of oxyflavans, due to the effect of adding a neutral salt, the use ratio of resorcinol to aliphatic ketone can be reduced compared to the conventional method, and therefore resorcinol can be produced. Oxyflavans of high purity can be efficiently produced under cost-effective conditions in which the amount of circulation to the reaction system is small and in a short reaction time. [Examples of the Invention] The present invention will be specifically described below with reference to Examples. Comparative Example 1 440 g (4.0 mol) of resorcinol and 37.9 g of a 36% aqueous hydrochloric acid solution were placed in a separable flask equipped with a stirrer, a cooling tube, a thermometer, and a pump for supplying aliphatic ketone.
(0.37 mol as HCl) and 114.3 g of water were charged and dissolved by heating, and the liquid temperature was brought to 50°C. 58.0 g (1.0 mol) of acetone was pumped into this at a constant rate over 45 minutes, and then
It held even longer. After the reaction is complete, the reaction mixture is
After neutralizing with 49.3 g (0.37 mol) of %NaOH aqueous solution, the precipitate in the reaction mixture was separated, the resulting crude cake was washed with water to remove the salt, and dried to give a white powder with a melting point of 217-219°C. 2,4,4-trimethyl-2-(2,4-dihydroxyphenyl)-7-
140.7 g of hydroxychroman was obtained. The purity of this product was over 99%. The results are shown in Table 1 together with the reaction conditions. Comparative Example 2 Table 1 shows the results obtained in the same manner as in Comparative Example 1, except that the holding time after acetone supply was shortened from 2 hours to 1 hour. Example 1 26.2g of sodium chloride as a neutral salt in the reaction system
The same procedure as Comparative Example 2 was carried out except that 2,4,4-trimethyl-2-(2,4-
The results of obtaining dihydroxyphenyl)-7-hydroxychroman are shown in Table 1. In this case, since the reaction rate was faster than in Comparative Examples 1 and 2, the desired product could be obtained in a high yield in a short time. Comparative Example 3 Resorcinol 220g (2.0mol), 36% hydrochloric acid aqueous solution
2,4,4-trimethyl-2-
The results of obtaining (2,4-dihydroxyphenyl)-7-hydroxychroman are shown in Table 1. Example 2 A reaction was carried out in exactly the same manner as in Comparative Example 2, except that 38.9 g (0.67 mol) of sodium chloride, a neutral salt, was added and the holding time was 4 hours. 2,4-dihydroxyphenyl)
The results of obtaining -7-hydroxychroman are shown in Table 1. 【table】

Claims (1)

[Claims] 1. When producing polyalkyl-2-(2,4-dihydroxyphenyl)-7-hydroxychroman by reacting an aliphatic ketone with resorcinol, the reaction is carried out in the presence of an acidic catalyst and a neutral salt. A method characterized by doing.