Method of manufacturing ferulic acid

Abstract: A waste oil, an alkaline oil cake, and a crude fatty acid which are discarded as waste materials or obtained as a by-product in the manufacture of rice salad oil are subjected to hydrolysis in the presence of an alkali so as to efficiently manufacture ferulic acid. The waste materials or by-product accompanying the manufacture of rice salad oil or rice fatty acid, which were disposed of by means of burning in the past, are effectively utilized in the method of the present invention.

Description: The present invention relates to a method of manufacturing ferulic acid which is used as a raw material in the manufacture of, for example, medicines, agricultural chemicals, cosmetics, pigments, and food additives. It is known that ferulic acid is manufactured by the condensation reaction of vanillin with malonic acid, as described in, for example, "Journal of the American Chemical Society, 74, 5346 (1952)". The condensation reaction certainly produces ferulic acid in a high yield. However, it takes as long as about three weeks to manufacture the product ferulic acid, making the known condensation method unsuitable for use in the commercial manufacture of ferulic acid, as described in, for example, "J.R. Johnson, Organic Reactions 1, 250 (1942)". In addition, the product ferulic acid is a mixture of trans- and cis-isomers. Under the circumstances, vigorous researches are being made in this technical field in an attempt to develop a method of manufacturing ferulic acid, which permits commercially manufacturing ferulic acid of high purity, i.e., ferulic acid which does not contain cis-isomer. In the manufacture of rice salad oil, some by-products and waste materials are discharged, for example, a blackish brown waste oil having a high viscosity, an alkaline oil cake rich in oil components, which is called soap stock, and a by-product rich in crude fatty acids, which is called dark oil. These waste materials and by-products are known to contain useful components. However, it was customary for these waste materials and by-products to be disposed of as useless industrial waste materials by, for example, a burning treatment, because a technique for effectively utilizing these waste materials was unknown in this technical field. The present inventors have investigated the components of the waste materials and the by-product noted above, and then have found by the chromatographic method that about 10 to 30% by weight of γ-oryzanol is contained in the waste material or the by-product. Certainly, γ-oryzanol itself is a useful component. However, since components other than γ-oryzanol are contained in large amounts in these waste materials or the by-products, it is difficult to recover effectively γ-oryzanol alone, leading to a high manufacturing cost of γ-oryzanol. Thus, it is economically impossible to recover γ-oryzanol from the industrial waste materials or the by-products noted above. An object of the present invention is to provide a method of manufacturing ferulic acid by hydrolyzing γ-oryzanol contained in an industrial waste material or a by-product in the presence of an alkali, in place of directly extracting γ-oryzanol from the waste materials or by-products noted above. Another object is to provide a method of effectively utilizing the waste materials and by-products which are discharged by the manufacture of rice salad oil. In the method of the present invention, the waste material, by-product or a crude γ-oryzanol is subjected to hydrolysis in the presence of an alkali so as to manufacture ferulic acid. Fig. 1 shows a typical formula of chemical reactions involved in the method of the present invention. In general, sodium hydroxide or potassium hydroxide is used as an alkali in the step of hydrolyzing γ-oryzanol. It is also possible to use other alkaline compounds such as LiOH, RuOH, Na₂CO₃, K₂CO₃ and NaHCO₃. It should be noted that the waste material or the by-product used as a raw material is quite immiscible with water. Thus, it is desirable to use a suitable alcohol as a solvent in the step of carrying out the hydrolysis in the presence of an alkali. In the case of using a simple alcohol having a small number of carbon atoms, which can be infinitely dissolved in water, the alkaline compound as well as the waste material or by-product in the reaction system can also be dissolved without difficulty. In carrying out the hydrolysis, it is desirable to set the temperature of the reaction mixture at 90 to 100°C. The reaction time should desirably be 8 to 10 hours. The reaction should desirably be carried out under an atmospheric pressure. Further, the pH of the reaction mixture should desirably be at least 10. A crude ferulic acid having a purity of about 70 to 90% can be obtained as a result of the hydrolysis in the presence of an alkali. In the next step, a solution containing an alkali salt of ferulic acid is acidified with, for example, a dilute sulfuric acid so as to precipitate ferulic acid in the solution, followed by separating the precipitated ferulic acid by means of filtration. Heat is generated by the neutralizing reaction in this step. Thus, it is desirable to cool by suitable means the solution containing the alkali salt of ferulic acid so as to maintain the temperature of the solution at 30°C or less in precipitating ferulic acid. The concentration of sulfuric acid or the like used for the neutralization should desirably be about 10 to 30%. Also, it is desirable to add sulfuric acid or the like such that the solution after the addition of acid should have a pH lower than 4. The crude ferulic acid separated by filtration is dissolved in hot water (about 90 to 100°C) and, then, the system is cooled so as to permit precipitation of ferulic acid. As a result, obtained is a pure trans-ferulic acid. The ferulic acid obtained by the method of the present invention can be used as a raw material in the manufacture of, for example, medicines, agricultural chemicals, cosmetics, pigments, and food. Methods of manufacturing these articles from ferulic acid are known to the art. To be more specific, methods of manufacturing cosmetics using ferulic acid as a raw material are described in, for example, Published Unexamined Japanese Patent Application No. 62-120312, Published Unexamined Japanese Patent Application No. 64-13017, and Published Unexamined Japanese Patent Application No. 2-167291. Methods of manufacturing medicines from using ferulic acid as a raw material are described in, for example, Published Unexamined Japanese Patent Application No. 61-204196, Published Unexamined Japanese Patent Application No. 61-204126, Published Unexamined Japanese Patent Application No. 64-13016, and Published Unexamined Japanese Patent Application No. 1-186835. Further, the use of ferulic acid as food additives are described in, for example, Published Unexamined Japanese Patent Application No. 63-283552. It should be noted in particular that the method of the present invention makes it possible to manufacture ferulic acid useful in the industries from a waste material or a by-product which is discharged by the manufacture of rice salad oil. This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: Fig. 1 exemplifies a typical chemical formula of reactions utilized in the method of the present invention; and Fig. 2 schematically shows the typical steps included in the method of the present invention. Let us describe some examples of the present invention. Example 1 10 g of a blackish brown waste oil called pitch, which is discharged as a by-product in producing a rice fatty oil from rice bran, was put in a three-necked flask. Then, 5g of sodium hydroxide, 20 mℓ of water and 20 mℓ of isopropyl alcohol were added to the waste oil. The mixture in the system was heated to 90 to 100°C until the mixture was boiled, and was stirred for about 8 hours at that temperature. The reaction was carried out for 8 to 10 hours at 90 to 100°C under an atmospheric pressure (1 atm.). After the reaction, the reaction system was cooled, followed by pouring hexane into the reaction mixture so as to remove the materials soluble in hexane. Then, a dilute sulfuric acid was added to the aqueous solution after removal of the materials soluble in hexane so as to acidify the aqueous solution and, thus, to precipitate ferulic acid. The temperature at which ferulic acid was deposited was 30°C or less, the concentration of the dilute sulfuric acid was 10 to 30%, and the pH of the aqueous solution was 1 to 4. The aqueous solution containing the precipitated ferulic acid was filtered so as to obtain 1.2g of crude ferulic acid having a purity of 80%. The crude ferulic acid thus obtained was dissolved in hot water of 90 to 100°C, followed by cooling the resultant solution for recrystallization, thereby obtaining pure trans-ferulic acid. The chemical structure of the product trans-ferulic acid was confirmed by the measurement with NMR spectrum and infrared ray spectrum. The trans-ferulic acid thus obtained was found to have a melting point of 174°C. The yield of ferulic acid based on the raw material waste oil was 9.6% by weight and the molar yield of ferulic acid based on γ-oryzanol was 100%. Further, the purity of the product ferulic acid was found to be 99.9%. Example 2 Operations as in Example 1 were carried out, except that 5g of potassium hydroxide was used in place of sodium hydroxide used in Example 1. Obtained was 1.0g of crude ferulic acid. The yield of ferulic acid based on the raw material waste oil was 8% by weight and the molar yield of ferulic acid based on γ-oryzanol was 83%. Further, the purity of the product ferulic acid was found to be 99.9%. Example 3 Operations as in Example 1 were carried out, except that 10g of an alkaline oil cake rich in oil components, which is called soap stock, was used in place of the blackish brown waste oil used in Example 1. Obtained was 0.2g of crude ferulic acid. The yield of ferulic acid based on the raw material alkaline oil cake was 2% by weight. Further, the purity of the product ferulic acid was found to be 99.9%. Example 4 Operations as in Example 1 were carried out, except that 10g of a by-product called dark oil, which is rich in crude fatty acid, was used in place of the blackish brown waste oil used in Example 1. Obtained was 0.3g of crude ferulic acid. The yield of ferulic acid based on the raw material dark oil was 3% by weight. Further, the purity of the product ferulic acid was found to be 99.9%. Example 5 Operations as in Example 1 were carried out, except that 10g of a crude γ-oryzanol available on the market and having a purity of about 80% was used in place of the blackish brown waste oil used in Example 1. Obtained was 2.2g of crude ferulic acid. The yield of ferulic acid based on the raw material crude γ-oryzanol was 17 to 18% by weight, and the molar yield of the product ferulic acid based on γ-oryzanol was 86%. Further, the purity of the product ferulic acid was found to be 99.9%. The reaction conditions in the hydrolyzing step and the conditions of precipitate of ferulic acid in each of Examples 2 to 5 were equal to those in Example 1.

Claims: A method of manufacturing ferulic acid, characterized by the following step: subjecting a γ-oryzanol-containing raw material to hydrolysis in the presence of an alkali. The method according to claim 1, characterized by the following steps: subjecting the γ-oryzanol-containing raw material to hydrolysis in the presence of an alkali so as to obtain a solution containing an alkali salt of crude ferulic acid; acidifying the solution containing the alkali salt of crude ferulic acid so as to precipitate ferulic acid; filtering the solution containing the precipitated ferulic acid so as to separate the precipitated ferulic acid; and dissolving the separated ferulic acid in water, followed by precipitating ferulic acid. The method according to claim 1 or 2, characterized in that the raw material is selected from the group consisting of crude γ-oryzanol, a waste material, a by-product, and a mixture of the waste material and by-product accompanying the manufacture of rice salad oil or rice fatty acid from rice bran. The method according to any of claims 1 to 3, characterized in that the raw material is a waste oil accompanying the manufacture of rice fatty acid from rice bran. The method according to any of claims 1 to 3, characterized in that the raw material is an alkaline oil cake accompanying the manufacture of rice salad oil from rice bran. The method according to any of claims 1 to 3, characterized in that the raw material is a crude fatty oil accompanying the manufacture of rice salad oil from rice bran. The method according to any of claims 1 to 6, characterized in that the alkali used in the hydrolysis step is selected from the group consisting of sodium hydroxide, potassium hydroxide, LiOH, RuOH, Na₂CO₃, K₂CO₃, NaHCO₃, and a mixture thereof. The method according to any of claims 1 to 7, characterized in that the alkali used in the hydrolysis step is selected from the group consisting of sodium hydroxide, potassium hydroxide, and a mixture thereof. The method according to any of claims 1 to 8, characterized in that the hydrolysis is carried out by dissolving the raw material in an alcohol solvent. The method according to claim 9, characterized in that the alcohol solvent is formed of at least one compound selected from the group consisting of the compounds represented by the chemical formulae given below: CH₃-OH, C₂H₅-OH, CH₃CH₂CH₂-OH, CH₃CH₂CH₂CH₂-OH The method according to any of claims 2 to 10, characterized in that the water for dissolving the ferulic acid separated by filtration has a temperature of 90 °C to 100 °C. The method according to any of claims 1 to 11, characterized by the following steps: using a waste oil accompanying the manufacture of rice fatty acid from rice bran as the raw material; preparing a mixture by adding sodium hydroxide and isopropyl alcohol to the waste oil; heating the mixture while stirring the mixture, followed by cooling the heated mixture; pouring hexane into the reaction mixture so as to remove the materials soluble in the hexane; adding a dilute sulfuric acid to the aqueous solution remaining after removal of the materials soluble in hexane so as to acidify the aqueous solution and, thus, to permit precipitation of ferulic acid; filtering the aqueous solution containing the precipitated ferulic acid so as to obtain a crude ferulic acid; and dissolving the crude ferulic acid in hot water, followed by cooling the resultant solution to recrystallize to obtain a pure trans-ferulic acid. The method according to any of claims 1 to 11, characterized by the following steps: using a waste oil accompanying the manufacture of rice fatty acid from rice bran as the raw material; preparing a mixture by adding potassium hydroxide and isopropyl alcohol to the waste oil; heating the mixture while stirring the mixture, followed by cooling the heated mixture; pouring hexane to the reaction mixture so as to remove the materials soluble in the hexane; adding a dilute sulfuric acid to the aqueous solution remaining after removal of the materials soluble in hexane so as to acidify the aqueous solution and, thus, to permit precipitation of ferulic acid; filtering the aqueous solution containing the precipitated ferulic acid so as to obtain a crude ferulic acid; and dissolving the crude ferulic acid in hot water, followed by cooling the resultant solution so as to achieve recrystallization and, thus, to obtain a pure trans-ferulic acid. The method according to any of claims 1 to 11, characterized by the following steps: using an alkaline oil cake accompanying the manufacture of rice fatty acid from rice bran as the raw material; preparing a mixture by adding sodium hydroxide and isopropyl alcohol to the alkaline oil cake; heating the mixture while stirring the mixture, followed by cooling the heated mixture; pouring hexane into the reaction mixture so as to remove the materials soluble in the hexane; adding a dilute sulfuric acid to the aqueous solution remaining after removal of the materials soluble in hexane so as to acidify the aqueous solution and, thus, to permit precipitation of ferulic acid; filtering the aqueous solution containing the precipitated ferulic acid so as to obtain a crude ferulic acid; and dissolving the crude ferulic acid in hot water, followed by cooling the resultant solution so as to achieve recrystallization and, thus, to obtain a pure trans-ferulic acid. The method according to any of claims 1 to 11, characterized by the following steps: using a dark oil accompanying the manufacture of rice fatty acid from rice bran as the raw material; preparing a mixture by adding sodium hydroxide and isopropyl alcohol to the dark oil; heating the mixture while stirring the mixture, followed by cooling the heated mixture; pouring hexane into the reaction mixture so as to remove the materials soluble in the hexane; adding dilute sulfuric acid to the aqueous solution remaining after removal of the materials soluble in hexane so as to acidify the aqueous solution and, thus, to permit precipitation of ferulic acid; filtering the aqueous solution containing the precipitated ferulic acid so as to obtain a crude ferulic acid; and dissolving the crude ferulic acid in hot water, followed by cooling the resultant solution so as to achieve recrystallization and, thus, to obtain a pure trans-ferulic acid. The method according to any of claims 1 to 11, characterized by the following steps: using a crude γ-oryzanol having a purity of about 80 % as the raw material; preparing a mixture by adding sodium hydroxide and isopropyl alcohol to the crude γ-oryzanol; heating the mixture while stirring the mixture, followed by cooling the heated mixture; pouring hexane into the reaction mixture so as to remove the materials soluble in the hexane; adding a dilute sulfuric acid to the aqueous solution remaining after removal of the materials soluble in hexane so as to acidify the aqueous solution and, thus, to permit precipitation of ferulic acid; filtering the aqueous solution containing the precipitated ferulic acid so as to obtain a crude ferulic acid; dissolving the crude ferulic acid in hot water, followed by cooling the resultant solution so as to achieve recrystallisation and, thus, to obtain a pure trans-ferulic acid.

Inventors: HAYASHI CHIEKO, KATO KOJI, MINAMI SEIKO, NOMURA EISAKU, TANIGUCHI HISAJI, TSUNO TAKUO, HAYASHI, CHIEKO, KATO, KOJI, MINAMI, SEIKO, NOMURA, EISAKU, TANIGUCHI, HISAJI, TSUNO, TAKUO
Applicants: TSUNO FOOD IND CO LTD, WAKAYAMA PREFECTURE, TSUNO FOOD INDUSTRIAL CO., LTD.
Application year: 1992
Main classification: C07C59
IPC codes: C07C51, C07C27, C07C59