JP2010275221A - Method for producing 2,4,4-trimethyl-2 ', 4', 7-trihydroxyflavan - Google Patents

Abstract

To develop an efficient process for producing 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan.
In a process for producing 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan in which resorcin and acetone are reacted in the presence of an acid catalyst, 2,4 having a purity of 70 to 90%. , 4-Trimethyl-2 ′, 4 ′, 7-trihydroxyflavan is used as a seed crystal, A method for producing 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan.
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Description

  The present invention relates to a method for producing 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan.

  In the method for producing 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan, high-purity 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan is used as a seed crystal. It is known to use (see, for example, Patent Document 1 (see “Example 8” of “0066”)).

JP-A-8-12665

  However, such a production method uses a highly pure 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan as a seed crystal, and the purity of the product is 79%. In order to use the product as a seed crystal in the next production, further purification is required, and thus improvement of the process has been demanded.

  As a result of intensive studies on a more efficient method for producing 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan, the present inventor has reached the present invention.

That is, the present invention
1. In a method for producing 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan in which resorcin and acetone are reacted in the presence of an acid catalyst, 2,4,4-trimethyl having a purity of 70 to 90% A process for producing 2,4,4-trimethyl-2 ', 4', 7-trihydroxyflavan, characterized in that -2 ', 4', 7-trihydroxyflavan is used as a seed crystal;
as well as,
2. The production method according to item 1, wherein the acid catalyst is sulfuric acid;
Is to provide.

  According to the production method of the present invention, 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan obtained can be used as it is as a seed crystal in the next production.

Hereinafter, the present invention will be described in detail.
The present invention relates to a process for producing 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan in which resorcin and acetone are reacted in the presence of an acid catalyst, and the purity of 70% to 90% of 2,4 , 4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan is used as a seed crystal, and is a method for producing 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan . 2,4,4-Trimethyl-2′4′7-trihydroxyflavan is a compound represented by the following formula.

  The acid catalyst may be an acidic substance. For example, sulfuric acid, p-toluenesulfonic acid, hydrochloric acid, phosphoric acid and the like can be used, but sulfuric acid is preferable. These acid catalysts can be used as they are or as an aqueous solution having an appropriate concentration. Although there is no restriction | limiting in particular in the usage-amount of an acid catalyst, the range of 0.1-10 mol% is preferable with respect to preparation resorcinol, and the range of 0.5-5 mol% is still more preferable. The condensation reaction is preferably performed in an organic solvent immiscible with water. Examples of such organic solvents include aliphatic hydrocarbons, aromatic hydrocarbons, aromatic halogen-substituted hydrocarbons and the like. Specific examples of the aliphatic hydrocarbon are hexane, heptane, octane, decane, and the like. Specific examples of the aromatic hydrocarbon are toluene, xylene, ethylbenzene, and the like. Specific examples of the aromatic halogen-substituted hydrocarbon are: Chlorobenzene, dichlorobenzene and the like. Aromatic hydrocarbons are preferred, and toluene and xylene are more preferred. Such an organic solvent is preferably present in an amount of 1 to 3 times the weight of the charged resorcin. The charged molar ratio of resorcin is preferably in the range of 0.6 to 1.5 mol times, more preferably 0.8 to 1.3 mol times with respect to the charged acetone.

  The seed crystal may be added from the beginning of the reaction, may be added during the condensation reaction, or may be added after the condensation reaction, but is preferably added from the beginning of the reaction. The addition amount is preferably in the range of 0.5 to 10 mol% with respect to the charged resorcin. The purity of 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan as a seed crystal may be 70 to 90%, and other components are not particularly limited.

  The reaction temperature is not particularly limited, but it may be usually reacted in the range from 30 ° C. to the reflux temperature. The reaction mixture obtained by such a reaction usually contains a solid. The reaction mixture is treated with a base, filtered and solid-liquid separated, and if necessary, the catalyst, neutralized salt and unreacted raw material adhering to the obtained solid are sufficiently washed with water and dried. Gives 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan. As the base, sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, sodium carbonate and the like can be used, and sodium hydroxide is preferable. The base is preferably used as an aqueous solution having an appropriate concentration.

  The purity of 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan thus obtained is usually in the range of 70 to 90%, and this is compared with the following 2,4,4-trimethyl-2 ′. , 4 ′, 7-trihydroxyflavan can be used as it is as a seed crystal.

  EXAMPLES Hereinafter, although an Example, a test example, and a reference example are given and this invention is demonstrated concretely, this invention is not limited to these. In the following examples, 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan is abbreviated as FVR.

Example: A 500 ml four-necked flask equipped with a thermometer, a stirrer and a condenser was charged with 75.4 g (0.68 mol) of resorcin, and the inside of the flask was purged with nitrogen, and then 43.7 g (0.75 mol) of acetone and 138.0 g of toluene was charged and the temperature was raised to 40 ° C. to completely dissolve resorcin. To this, 7.1 g (purity 82%) of 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan (hereinafter abbreviated as FVR) was added. The flask was further charged with 0.69 g of 98% sulfuric acid, and the temperature was raised to an internal temperature of 77 ° C., and then kept at 76 to 79 ° C. for 12 hours. The obtained reaction mixture was neutralized by adding 5.5 g of a 10 wt% aqueous sodium hydroxide solution, cooled to room temperature, and the precipitate was collected by filtration. The obtained solid was washed with 200 g of water, and dried under reduced pressure at 80 ° C. for 5 hours under a reduced pressure of 1 kPa or less to obtain 94.5 g of a solid. The solid was analyzed by high performance liquid chromatography external standard method (hereinafter abbreviated as LC-ES method). As a result, the FVR content was 81.3% by weight and the resorcin content was 0.8% by weight. It was.

Comparative example In the said Example, except having made purity of FVR into 95%, operation was performed like the said Example and 94.0g of solid substance was obtained. As a result of analyzing the solid by the LC-ES method, the content of FVR was 82.2% by weight and the content of resorcin was 0.5% by weight.

  2,4,4-Trimethyl-2'4'7-trihydroxyflavan obtained by the production method of the present invention is a useful compound as a reinforcing agent and an intermediate for various rubber compositions.

Claims (2)

In a method for producing 2,4,4-trimethyl-2 ′, 4 ′, 7-trihydroxyflavan in which resorcin and acetone are reacted in the presence of an acid catalyst, 2,4,4-trimethyl having a purity of 70 to 90% A process for producing 2,4,4-trimethyl-2 ', 4', 7-trihydroxyflavan, characterized in that -2 ', 4', 7-trihydroxyflavan is used as a seed crystal. The production method according to claim 1, wherein the acid catalyst is sulfuric acid.