JPS606950B2 - Method for purifying coumarin and its derivatives - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is based on the following formula (wherein each substituent R, ~R6 may be a hydrogen atom or a C, ~C5 alkyl group).

However, the total number of substituent carbon atoms is not 10 or more). The method for producing this type of compound is described in British Patent No. 1,368 941 and Tsubaki Gansho 48-9.
It is described in the specification of No. 8166 (Japanese Unexamined Patent Publication No. 49-62473).

These compounds are of particular importance in the perfume industry and therefore must be of extremely high purity. The main criterion of purity generally required is the color of the coumarin, which is
It should be less than 70 days, preferably less than 70 days.
Impurities commonly found in coumarin include 3,4-dihydrocoumarin, ethylphenol, dihydrocinnamic acid, and esters of ethylphenol and dihydroccinnamic acid. Several methods are known for purifying coumarin. Examples include millet crab and recrystallization (e.g. Kirk-00
Me, Encycloped; aofChemica
Technology, 2nd Edition, Volume 6). However, the purity of coumarin obtained by such a method is not sufficient for application to the fragrance industry, for example, the color of purified coumarin is 125 to 2500 days old. On the other hand, according to another known method, the resinous components are continuously separated from the crude coumarin, the remaining coumarin is dissolved in concentrated sulfuric acid, air is passed through the resulting solution at high temperature, and this solution is treated with water. Purified coumarin can be obtained by precipitating coumarin, washing and neutralizing the precipitate, and then distilling it under reduced pressure. This process is complex, the color of the resulting product is approximately 2000 days, and a significant portion of the starting material is lost. There is another method
, Volume 70, 1937, P237,
In this method, a reaction mixture is obtained by dehydrogenation of dihydrocoumarin, the reaction mixture is distilled, the canidate is dissolved in an aqueous potassium hydroxide solution, the solution thus obtained is treated with an acid, and Coumarins have been recovered by applying ether extraction.

Even with this labor-intensive method, only a coumarin of insufficient purity was obtained from a practical point of view, and furthermore, in order to dissolve the reaction mixture in potassium hydroxide, a large amount of the reaction mixture, i.e., 100 days, was required. About 2.5 mol of potassium hydroxide is required.The present invention is based on the following general formula (wherein each substituent R, ~R6 is a hydrogen atom or a carbon atom 1~
In the method for purifying impure coumarin or alkylated coumarin, which is an alkyl group having 5 carbon atoms and the total number of carbon atoms in the substituents is not 10 or more, the coumarin is purified with a basic compound at a temperature of 20 to 150 °C. A method characterized by treating with an aqueous solution, separating the aqueous layer thus formed from the coumarin-containing layer, washing the coumarin-containing layer with water at a temperature of 20° to 150q0, and recovering purified coumarin compounds from the resulting washed layer. It provides:

The basic aqueous solution used is, for example, an alkali metal or alkali metal hydroxide, such as Na
Any aqueous solution of K〇day, Li〇day, Mg(〇H)2, Ca(OH)2 and axis (OH)2 may be used. Other solutions that can be used in the present invention are solutions of sodium or potassium carbonate, sodium or potassium acetate, and sodium or potassium benzoate. The amount of the basic compound in the solution is preferably 0.001 to 1 molar equivalent of coumarin 100 containing impurities. The optimum amount is determined in part by the amount and nature of the impurity. Often contains impurities coumarin 100% stiff basic compound 0.005
It is sufficient to use a solution containing ~0.1 molar equivalent.
The solution concentration can also be selected within a wide range; for example, the solution may contain from 0.1 to 1% by weight of the basic compound.
The temperature for processing and washing coumarin containing impurities is 70o.
A temperature of ~100 qo is preferred. Pressure is not critical, so the process can also be carried out at atmospheric pressure.
Purified coumarin compounds are extracted from the water-washed layer by various methods.
Preferably, it can be recovered by distillation.

The coumarin obtained by the method of the present invention has extremely high purity.
Can be used as is in the perfume industry, the color of the product is 70
Less than o days. If extremely pure coumarin is desired, this can be obtained by recrystallizing the coumarin product recovered by distillation, for example from ethanol. Next, examples of the present invention will be shown.

Example 1 186 ml of coumarin containing impurities and 186 ml of an aqueous sodium hydroxide solution (NaOHO.75% by weight) were introduced into a 500-sized flask equipped with a filter and a reflux condenser.

Impurity-containing coumarin includes 2% by weight of 3,4-dihydrocoumarin, 0.2% by weight of ethylphenol, and 0.2% by weight of dihydrocinnamic acid. % by weight of the box, and 0.5% by weight of high-boiling impurities consisting primarily of esters of ethylphenol and dihydrocinnamic acid.

Heat the mixture in the flask under reflux for 1 hour.
It was heated at midnight. The coumarin-containing layer was then separated from the aqueous layer and the organic layer was washed twice with a total of 180 portions of water. 170 ml of coumarin was recovered from the water-washed product by distillation. The purified coumarin product thus obtained is 99.9
% of coumarin, 0.01% by weight of ethylphenol, 0.03% by weight of dihydrocinnamic acid and 0.03% by weight of coumarin.
It contained % by weight of high-boiling impurities.

The color of the product was 650 days. Coumarin product 70
The solution was recrystallized from 250 ml of 50% ethanol.

The coumarin was then filtered and washed twice with a total of 50' of 20% ethanol. Dry the product to a purity of 99.95
More than 0.01% of highly purified coumarin 62%
It was obtained with less than % by weight of dihydrocinnamic acid and 0.01% by weight of high boiling impurities. The hue was 60°.
Example 0 Impurity-containing coumarin 40mg and sodium carbonate (Na2
C melon 0. An aqueous solution of 40% (% by weight) was introduced into a 100ml flask equipped with a flask and a reflux condenser.

The impure coumarin contains 90% by weight of coumarin, 2% by weight of 3,4-dihydrocoumarin, 0.2% by weight of ethylphenol, 0.3% by weight of dihydroccinnamic acid, and 0.2% by weight of ethylphenol.
It contained 5% by weight of high boiling point impurities. 1 at 100 pm while refluxing the mixture in the flask.
heated for an hour. The coumarin-containing layer was then separated from the basic compound-containing layer and washed twice with a total of 40' of water. Distill the organic layer and extract coumarin 99. Contains 0.01% by weight of ethylphenol and 0% dihydrocinnamic acid by weight of insects.
．． A purified coumarin containing 0.01% by weight and 0.02% by weight of high-boiling impurities was obtained. The color of the product was 6 days.

Comparative Experiment Example 1 100 tons of impurity-containing coumarin having the same composition as the impurity-containing coumarin used in Example 1 and 100 tons of sulfuric acid (QS04 with an increase of 8%) were added to a reflux condenser, a Nada combustor, and 250 tons of gas introduction loan. Skin [introduced into flask.

The mixture in the flask was heated with a candle at 110 qo for 2 hours, passing air through the contents at 135 liters per hour. The reaction mixture was then poured into 200 g of water, thereby obtaining a coumarin precipitate.

The precipitate was separated in a furnace, washed with water, and then distilled under reduced pressure. The resulting coumarin product contains 99.5% by weight of coumarin and 0.9% by weight of coumarin.
1% by weight of ethylphenol, 0. along with 3,4-dihydrocoumarin, 0.02% dihydroccinnamic acid, and 0.018% high boiling impurities.

The color of the product was 2000 days.

The embodiments of the present invention will be explained as follows.

{1' The solution of basic compound contains impurity coumarin 10
The method according to claim 1, wherein the basic compound is contained in an amount of 0.001 to 1 molar equivalent.

(2) The method according to claim or embodiment m, wherein the basic compound is an alkali metal hydroxide or an alkali metal carbonate.

[3} Claims and embodiment 1 in which the coumarin compound is recovered by distillation after the water washing process}, ■
The method described in any of the above.

{4} The method described in the preceding item '3'1, wherein the coumarin compound obtained by the distillation is recrystallized.

'51 A method as claimed substantially herein with particular reference to the Examples.

Claims (1)

[Claims] 1. The following general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, each substituent R_1 to R_6 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, The total number of carbon atoms is not more than 10), in a method for purifying impure coumarin or alkylated coumarin,
The coumarin is treated with an aqueous solution of a basic compound at a temperature of 20° to 150°C, the aqueous layer thus formed is separated from the coumarin-containing layer, and the coumarin-containing layer is heated to a temperature of 20° to 150°C.
A method characterized by washing with water and recovering a purified coumarin compound from the resulting washing layer.