KR100413373B1 - The improved method for the preparation of DL-α-tocopherol acetate - Google Patents

Abstract

The present invention relates to a process for preparing DL-α-tocopherol acetate, wherein a catalyst is charged in a fixed bed continuous reactor, and a reactant consisting of DL-α-tocopherol and acetic anhydride is continuously added to the reactor under a reaction temperature of from room temperature to 250 ° C. By supplying and performing an acylation reaction, it is related with the method of manufacturing high yield and high purity DL- (alpha)-tocopherol acetate. By the method according to the present invention, DL-α-tocopherol acetate of high yield and high purity can be prepared, preventing the inclusion of the catalyst component in the reaction product, reducing the manufacturing cost, and reducing the industrial waste generated after the manufacture. Can be.

Description

The improved method for the preparation of DL-α-tocopherol acetate}

The present invention relates to a method for preparing DL-α-tocopherol acetate, and more particularly, a catalyst is charged into a fixed-phase continuous reactor, and reacted with DL-α-tocopherol and acetic anhydride under appropriate reaction conditions. The present invention relates to a process for producing DL-α-tocopherol acetate with high yield and high purity by continuously supplying the reactor to an acylation reaction.

DL-α-tocopherol is oxidized when exposed to air and light, so it is converted into acetate form for distribution, storage and transport. Although many attempts have been made over the last decades for the efficient production of DL-α-tocopherols, little attention has been given to converting the prepared DL-α-tocopherols to DL-α-tocopherol acetates, so the patent registration is an independent patent. Has been treated in the form briefly mentioned in the patent of DL-α-tocopherol.

For example, Roche Vitamins Inc., US Pat. No. 5,886,196, uses DL-α-tocopherol and acetic anhydride using hydrogen bis (oxalato) borate as a catalyst. A method of synthesizing DL-α-tocopherol acetate by reaction for 1 hour in a batch type reator is described. In addition, U.S. Patent No. 4,217,285 to Nissin Flour Milling Co., Ltd. uses sodium acetate and metal zinc powder as catalysts to make the reaction temperature 95 to 100 ° C. in a batch reactor. A method of synthesizing DL-α-tocopherol acetate by reacting DL-α-tocopherol with acetic anhydride for a period of time is described.

As such, the methods mentioned in the patents of the prior art all produce DL-α-tocopherol acetate in a batch reactor. In addition, the aforementioned hydrogen bis (oxalto) borate is not a readily available general purpose compound, but is expensive, and zinc powder is easily converted into an oxide form when exposed to moisture. In addition, in order to increase the purity of DL-α-tocopherol acetate after the reaction, there is a problem in that these catalysts have to be separated from the reaction product, and the reaction is carried out in a batch reactor using the catalyst, which makes the process before and after the reaction apparatus complicated and time consuming. do. In other words, since the reaction product is introduced into a batch reactor and heated to the reaction temperature and reacted during the reaction time, it is required to be transferred to the separation and purification process at the next stage. In addition, there is a disadvantage that the catalyst used must be removed in a subsequent separation and purification process.

As a result of the study by the present inventors, the high-yield, high-purity DL can be achieved by minimizing the time required for heating and reaction by carrying out the reaction in the presence of a catalyst and in a fixed bed continuous reactor, and simplifying the post-stage process to be cost competitive. It has been found that -α-tocopherol acetate can be prepared, and the present invention has been completed based on this.

Accordingly, an object of the present invention is to solve the problems of the prior art, to minimize the time required for heating and reaction, and to provide a method for producing DL-α-tocopherol acetate, which is cost-competitive, high-yield, and high-purity by simplifying the post-stage process. have.

In order to achieve the above object, a high yield, high purity DL-α-tocopherol acetate production method of the present invention is filled with a catalyst in a fixed-phase continuous reactor, DL-α-tocopherol and acetic anhydride under a reaction temperature of room temperature to 250 ℃ It consists of continuously reacting the reaction product consisting of the acylation reaction for 30 minutes to 2 hours.

Hereinafter, the present invention will be described in more detail.

As described above, conventionally, only a batch reactor has been used as a method of converting DL-α-tocopherol to DL-α-tocopherol acetate, and there is no example of using a continuous reactor as in the present invention. As such, when a batch reactor is used, it takes a long time for introduction of the reactants, heating, transfer after the reaction, etc., and there is a problem in that the catalyst used must be removed in a subsequent separation and purification process. On the other hand, the process according to the invention can be used more efficiently than the prior art methods by filling the catalyst in a fixed bed continuous reactor and continuously injecting the reactants into the reactor preheated to the desired temperature. It is a very effective method that does not require separation of the catalyst.

In addition, the catalyst added to proceed the reaction more quickly is not easy to use a catalyst that is difficult to obtain conventionally, but the handling is simple and economical by using a silica alumina catalyst or an ion exchange resin catalyst that is used in various ways as a filler.

A silica alumina catalyst or an ion exchange resin catalyst used as the catalyst is preferable, but the ion exchange resin catalyst usable in the present invention is not particularly limited as a cation exchange resin containing H ⁺ (or SO ₃ H ⁺ ), For example, Amberlyst 35 is an Amberlyst based catalyst manufactured by Dow Chemical Co., Ltd. , 36 and the like can be used. The ion exchange resin catalyst is not particularly limited in size or shape, but may be any size or shape that can be used in a fixed bed reactor.

In addition, in the case of the silica alumina catalyst, any amount of 13 to 25% by weight of alumina may be used. However, since the reaction of the present invention takes place on the surface of the catalyst, the larger the BET surface area of the catalyst is preferable, for example, the BET surface area per 1 g of the catalyst. It is further more preferable if it is 400 m <^2> . In addition, it is particularly preferable to form silica alumina by a generally known method and to make it into a spherical or cylindrical shape. On the other hand, it is appropriate to use a catalyst having an average pore diameter of 1 nanometer or more so that the reactant DL-α-tocopherol and the reaction product DL-α-tocopherol acetate can freely pass through the catalyst.

The catalyst described above is charged into a fixed bed continuous reactor, and then acylated at an appropriate reaction temperature for 30 minutes to 2 hours to prepare DL-α-tocopherol acetate. First, the reaction temperature ranges from room temperature to 250 ° C. The higher the reaction proceeds well, but when the degree of reaction exceeds 250 ° C., the vapor pressure of acetic anhydride, which is a reactant, and acetic acid, which is a reaction product, becomes too high. For example, when the catalyst is silica alumina, the temperature is preferably from room temperature to 200 ° C. On the other hand, in the case of the ion exchange resin catalyst, since the heat resistance of the catalyst itself is weak, a temperature range of 130 ° C. at room temperature is more preferable. In addition, it is preferable to carry out reaction pressure which has a correlation with reaction temperature in reaction conditions generally in the range of 1-20 atmospheres.

On the other hand, the amount of acetic anhydride in the reactant is theoretically possible as long as the number of moles such as DL-α-tocopherol, the more the effect of promoting the reaction. However, if the amount of acetic anhydride is too large, the size of the separation process at the rear end should be large, so that it is preferable to use 1 to 8 times in molar ratio compared to DL-α-tocopherol, and more preferably 1 to 4 times. In addition, the longer the residence time of the reactants in the reactor, the better, but longer residence times require reactions for approximately 30 minutes to 2 hours since a larger reactor is required to produce the same amount of DL-α-tocopherol acetate. .

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited thereto.

Example 1

After filling 10 g of Amberlyst 35 catalyst of Rohm Haas Co., Ltd. with ion exchange resin catalyst in a fixed bed continuous reactor, 1 kg (2.32 mol) of DL-α-tocopherol and 0.5 kg (4.90 mol) of acetic anhydride were added to a beaker, followed by stirring at room temperature. Was prepared. 48 g per hour was sent while maintaining the temperature of the reactor at 50 ° C. After waiting for 2 hours until the composition of the reaction product becomes constant, the reaction progress was confirmed by gas phase chromatography. As a result, the conversion rate of DL- (alpha) -tocopherol was 99.5%.

Examples 2 and 3

0.375 kg (3.67 mol) of acetic anhydride was used, and the reaction temperature and the amount of raw materials processed per hour were adjusted in the same manner as in Example 1 to obtain DL-α-tocopherol acetate, and DL-α -The results of confirming the conversion rate of tocopherol are shown in Table 1 below.

Example 4

A catalyst was used in the same manner as in Example 1 except that silica alumina was used to obtain DL-α-tocopherol acetate, and the results of confirming the conversion of DL-α-tocopherol are shown in Table 1 below.

Example Raw material amount per hour (g) Reaction temperature (℃) % Conversion One 48 50 99.5 2 8 85 100 3 17 83 100 4 100 139 100

As can be seen from the above examples, the method according to the present invention is carried out by filling a silica alumina or ion exchange resin catalyst in a fixed-phase continuous reactor, thereby facilitating the handling of the catalyst, and the catalyst component in the reaction product. This content can be prevented at the source and the reaction process is simplified. Therefore, it is possible to lower the production cost of DL-α-tocopherol acetate and to reduce industrial waste generated after the production. The prepared DL-α-tocopherol acetate also has excellent yields and purity that are inferior to methods using conventional batch reactors.

Claims (4)

The catalyst is charged in a fixed bed continuous reactor, and reactants composed of DL-α-tocopherol and acetic anhydride are continuously supplied to the reactor at a reaction temperature of from room temperature to 250 ° C. to perform an acylation reaction for 30 minutes to 2 hours. A high yield, high purity DL-α-tocopherol acetate production method. The method of claim 1, wherein the catalyst is silica alumina or ion exchange resin. According to claim 1, wherein the reaction temperature is a high yield, high purity of the DL-α-tocopherol acetate, characterized in that when the catalyst is silica alumina from room temperature to 200 ℃, if the ion exchange resin Manufacturing method. The method of claim 1, wherein the amount of acetic anhydride in the reactant is 1 to 4 times in molar ratio with respect to DL-α-tocopherol.