CN114181210B - Preparation method of tetrahydrofolic acid - Google Patents

Abstract

The invention relates to a preparation method of tetrahydrofolic acid, which comprises the following steps: adding Pd/C catalyst and folic acid solution into a reaction kettle, filling hydrogen into the reaction kettle, placing the reaction kettle in an environment of 40-90 ℃, carrying out oxidation-reduction reaction on folic acid and hydrogen, and obtaining tetrahydrofolic acid after the reaction is finished. The preparation method of the tetrahydrofolic acid provided by the invention solves the problem of low preparation yield of the tetrahydrofolic acid under the condition of meeting the requirement of reducing the catalyst dosage.

Description

A method for preparing tetrahydrofolic acid

Technical Field

The invention relates to the technical field of drug synthesis, and in particular to a method for preparing tetrahydrofolic acid.

Background technique

Tetrahydrofolate is a coenzyme of one-carbon group (including CH ₃ , CH ₂ , CHO, etc.) transferase. Tetrahydrofolate has the function of transferring one-carbon groups and participates in many important reactions and the synthesis of nucleic acids and amino acids.

Currently, tetrahydrofolic acid is generally prepared by catalytic hydrogenation reduction of folic acid.

The catalysts commonly used in the catalytic hydrogenation reduction method are Pt/C (platinum-carbon catalyst), Rh/C (rhodium-carbon catalyst) and PtO ₂ (platinum dioxide catalyst). The amount of catalyst used is large and the catalytic effect is not ideal, resulting in a low yield of tetrahydrofolate preparation.

Summary of the invention

Based on this, the present invention provides a method for preparing tetrahydrofolate, which solves the problem of low yield of tetrahydrofolate preparation while meeting the requirement of reducing the amount of catalyst used.

The present invention provides a method for preparing tetrahydrofolate, comprising the steps of:

Adding a Pd/C catalyst and a pH folic acid solution into a reactor, filling the reactor with hydrogen, placing the reactor in an environment of 40-90° C., allowing the folic acid to undergo an oxidation-reduction reaction with the hydrogen, and obtaining tetrahydrofolic acid after the reaction is completed;

The reaction equation for preparing tetrahydrofolic acid is as follows:

The chemical formula of folic acid is:

The chemical formula of tetrahydrofolate is:

Preferably, the catalyst Pd/C comprises 10% Pd/C, and the mass ratio of the folic acid to the catalyst 10% Pd/C is 100:(0.1-20).

Preferably, in the step of the folic acid and the hydrogen undergoing redox reaction, the pressure range of the reactor is 20-65 bar.

Preferably, the reaction time of the redox reaction between the folic acid and the hydrogen is 6-24 hours.

Preferably, after the reaction is completed, the step of obtaining tetrahydrofolic acid comprises:

After the reaction is completed, a solution containing tetrahydrofolic acid is obtained, and the pH of the solution containing tetrahydrofolic acid is adjusted to 3-3.5 with an acid solution to obtain a solution containing tetrahydrofolic acid precipitate, and the solution containing tetrahydrofolic acid precipitate is filtered to collect the tetrahydrofolic acid precipitate, and the precipitate is dried to obtain tetrahydrofolic acid.

Preferably, the pH of the folic acid solution is 6-7, and the preparation of the folic acid solution comprises the steps of:

Solid folic acid is added into a flask, nitrogen or an inert gas is filled into the flask to form an oxygen-free environment, a buffer solution is added into the flask, and the mixture is stirred until uniform to obtain a mixed solution, and the pH of the mixed solution is adjusted to 6-7 with an alkaline solution to obtain a folic acid solution.

Preferably, the pH of the buffer solution is 4-10.

Preferably, the buffer solution includes any one of disodium hydrogen phosphate-citric acid buffer solution, sodium dihydrogen phosphate-disodium hydrogen phosphate buffer solution, disodium hydrogen phosphate-potassium dihydrogen phosphate buffer solution, sodium barbital-hydrochloric acid buffer solution, tris(hydroxymethylaminomethane)-hydrochloric acid buffer solution, boric acid-borax buffer solution, glycine-sodium hydroxide buffer solution, borax-sodium hydroxide buffer solution, sodium carbonate-sodium bicarbonate buffer solution, Britton-Robinson buffer solution and Tris buffer saline solution.

Preferably, the alkaline solution includes any one of a NaOH solution and a KOH solution.

Preferably, the amount of the buffer solution is 10-15 ml/1 g of solid folic acid.

Compared with the existing solutions, the present invention has the following beneficial effects:

The invention prepares tetrahydrofolic acid by reducing folic acid under the catalysis of a catalyst Pd/C. The catalyst Pd/C has high catalytic efficiency and can be recycled, thus overcoming the problems of large catalyst dosage and low yield in the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a graph showing the experimental results of the effect of pH of a folic acid solution on tetrahydrofolate yield;

FIG2 is a graph showing the experimental results of the effect of reaction time on tetrahydrofolate yield;

FIG3 is a graph showing the experimental results of the effect of reaction temperature on tetrahydrofolate yield;

FIG4 is an experimental result diagram showing the effect of the amount of catalyst Pd/C on the yield of tetrahydrofolate;

FIG5 is the NMR image of the product tetrahydrofolate.

Detailed ways

The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

The experimental methods in the following examples are conventional methods unless otherwise specified. The experimental materials and reagents used in the following examples are all commercially available unless otherwise specified. The quantitative tests in the following examples were performed in triplicate, and the data are the average or average ± standard deviation of the triplicate experiments.

In addition, the "and/or" in the full text includes three solutions. Taking A and/or B as an example, it includes technical solution A, technical solution B, and a technical solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

The present invention provides a method for preparing tetrahydrofolic acid, comprising the steps of:

Pd/C catalyst and folic acid solution are added into a reactor, hydrogen is introduced into the reactor, and the reactor is placed in an environment of 40-90° C., folic acid and hydrogen undergo redox reaction, and tetrahydrofolic acid is obtained after the reaction is completed;

The reaction equation for preparing tetrahydrofolic acid is as follows:

Among them, the chemical formula of solid folic acid is:

The chemical formula of tetrahydrofolate is:

The invention prepares tetrahydrofolic acid by reducing folic acid under the catalysis of a catalyst Pd/C. The catalyst Pd/C has high catalytic efficiency and can be recycled, thus overcoming the problems of large catalyst dosage and low yield in the prior art.

Hydrogen reduces the carbon-nitrogen double bond in folic acid. Specifically, hydrogen is adsorbed on the surface of the catalyst Pd/C, folic acid coordinates with the catalyst, and the hydrogen molecules of hydrogen break their bonds under the catalysis of the catalyst Pd/C to form active hydrogen atoms. The hydrogen atoms of hydrogen combine with the carbon-nitrogen double bond of folic acid to reduce to form a carbon-nitrogen single bond, thereby generating tetrahydrofolic acid.

Pd/C refers to palladium carbon, in which palladium microcrystals are evenly impregnated on a special porous carbon carrier.

Specifically, hydrogen is charged into the reactor until the reactor contains no gas other than hydrogen;

In the steps of adding the catalyst Pd/C into the reactor and adding the folic acid solution into the reactor, nitrogen or an inert gas is charged into the reactor to form an oxygen-free environment in the reactor.

In some embodiments, the catalyst Pd/C includes 10% Pd/C, and the mass ratio of folic acid to the catalyst 10% Pd/C is 100:(0.1-20).

In some embodiments, in the step of redox reaction of folic acid and hydrogen, the pressure of the reactor is in the range of 30-65 bar.

In some embodiments, the reaction time of the redox reaction of folic acid and hydrogen is 6-24 hours.

In some embodiments, after the reaction is completed, the step of obtaining tetrahydrofolic acid includes:

After the reaction is completed, a solution containing tetrahydrofolic acid is obtained, and the pH of the solution containing tetrahydrofolic acid precipitate is adjusted to 3-3.5 with an acid solution to obtain a solution containing tetrahydrofolic acid precipitate, and the solution containing tetrahydrofolic acid precipitate is filtered to collect the tetrahydrofolic acid precipitate, and the precipitate is dried to obtain tetrahydrofolic acid.

Specifically, after the reaction is completed, the entire system is homogeneous, and tetrahydrofolate will precipitate under acidic conditions, with pH 3-3.5 being the time when the precipitation yield of tetrahydrofolate is the highest;

Tetrahydrofolate is sensitive to oxygen and can be easily oxidized to dihydrofolate, so the entire reaction process requires an anaerobic environment;

Specifically, the drying method includes freeze drying, vacuum drying, etc., and drying under anaerobic conditions to prevent tetrahydrofolate from being oxidized;

Filtration should be performed under nitrogen or inert gas to avoid oxidation of tetrahydrofolate.

In some embodiments, the pH of the folic acid solution is 6-7, and the preparation of the folic acid solution comprises the steps of:

Solid folic acid is added to a flask, nitrogen or an inert gas is filled into the flask to form an oxygen-free environment, a buffer solution with a pH value of 4 to 7 is added to the flask, and the mixture is stirred until uniform to obtain a mixed solution, and the pH value of the mixed solution is adjusted to 6 to 7 with an alkaline solution to obtain a folic acid solution.

Specifically, the folic acid solution is prepared at room temperature, i.e., 25-35°C.

Specifically, the buffer solution is added to control the pH of the solution and avoid titration jumps;

Specifically, folic acid will dissolve in an alkaline solution. When the pH of the folic acid solution is adjusted to 7 using an alkaline solution, the yield of tetrahydrofolic acid generated by the reaction of folic acid reaches the highest.

In some embodiments, the buffer solution includes any one of disodium hydrogen phosphate-citric acid buffer solution, sodium dihydrogen phosphate-disodium hydrogen phosphate buffer solution, sodium dihydrogen phosphate-potassium dihydrogen phosphate buffer solution, sodium barbital-hydrochloric acid buffer solution, tris(hydroxymethylaminomethane)-hydrochloric acid buffer solution, boric acid-borax buffer solution, glycine-sodium hydroxide buffer solution, borax-sodium hydroxide buffer solution, sodium carbonate-sodium bicarbonate buffer solution, Britton-Robinson buffer solution and Tris buffered saline solution.

In some embodiments, the alkaline solution includes any one of a NaOH solution and a KOH solution.

In some embodiments, the amount of buffer solution used is 10-15 ml/1 g solid folic acid.

Specifically, the drying method includes freeze drying, vacuum drying, etc., and drying is performed under anaerobic conditions to prevent tetrahydrofolate from being oxidized.

In some embodiments, it also includes:

Tetrahydrofolate was detected by NMR using trimethoxybenzene as an internal standard.

Example 1

Under 25°C, 1 g of solid folic acid was added to a 100 mL three-necked flask, the flask was replaced with nitrogen three times, 10 mL of 0.2 mol/L NaH ₂ PO ₄ -Na ₂ HPO ₄ buffer solution with a pH of 7 was added to the flask, and the mixture was stirred until uniform to obtain a mixed solution, and the pH of the mixed solution was adjusted to 7 with a 20% NaOH solution to obtain a folic acid solution;

0.1 g of 10% Pd/C was added to a 50 mL reactor. After the reactor was replaced with nitrogen for 3 times, a folic acid solution with a pH of 7 was added to the reactor. After the reactor was replaced with hydrogen for 5 times, hydrogen was filled into the reactor. The pressure of the reactor was adjusted to 50 bar. The reactor was placed in an environment of 60° C. for redox reaction. The reaction was performed for 15 hours. After the reaction was completed, a solution containing tetrahydrofolic acid was obtained. The pH of the solution containing tetrahydrofolic acid was adjusted to 3 with a 1 mol/L hydrochloric acid solution to precipitate tetrahydrofolic acid. The precipitate was filtered and dried in a vacuum drying oven for 8 hours to obtain tetrahydrofolic acid.

Tetrahydrofolate was detected using mesitylene glycol as an internal standard, and the yield of tetrahydrofolate was found to be 93%.

Example 2

At 28°C, 1 g of solid folic acid was added to a 100 mL three-necked flask, the flask was replaced with nitrogen three times, 10 mL of 0.2 mol/L NaH ₂ PO ₄ -Na ₂ HPO ₄ buffer solution with a pH of 7 was added to the flask, and the mixture was stirred until uniform to obtain a mixed solution, and the pH of the mixed solution was adjusted to 7 with a 20% NaOH solution to obtain a folic acid solution;

0.2 g of 10% Pd/C was added to a 50 mL reactor. After the reactor was replaced with nitrogen for 3 times, a folic acid solution with a pH of 7 was added to the reactor. After the reactor was replaced with hydrogen for 5 times, hydrogen was filled into the reactor. The pressure of the reactor was adjusted to 30 bar. The reactor was placed in an environment of 70° C. for oxidation-reduction reaction. The reaction was performed for 15 hours. After the reaction was completed, a solution containing tetrahydrofolic acid was obtained. The pH of the solution containing tetrahydrofolic acid was adjusted to 3 with a 1 mol/L hydrochloric acid solution to precipitate tetrahydrofolic acid. The precipitate was filtered and dried in a vacuum drying oven for 8 hours to obtain tetrahydrofolic acid.

Tetrahydrofolate was detected using mesitylene glycol as an internal standard, and the yield of tetrahydrofolate was found to be 91%.

Example 3

At 30°C, 1 g of solid folic acid was added to a 100 mL three-necked flask. After the flask was replaced with nitrogen three times, 10 mL of a 0.2 mol/L NaH ₂ PO ₄ -Na ₂ HPO ₄ buffer solution with a pH of 7 was added to the flask, and the mixture was stirred until uniform to obtain a mixed solution. The pH of the mixed solution was adjusted to 7 with a 20% NaOH solution to obtain a folic acid solution.

0.1 g of 10% Pd/C was added to a 50 mL reactor. After the reactor was replaced with nitrogen for 3 times, a folic acid solution with a pH of 7 was added to the reactor. After the reactor was replaced with hydrogen for 5 times, hydrogen was filled into the reactor. The pressure of the reactor was adjusted to 50 bar. The reactor was placed in an environment of 80° C. for a redox reaction to occur for 15 hours. After the reaction was completed, a solution containing tetrahydrofolic acid was obtained. The pH of the solution containing tetrahydrofolic acid was adjusted to 3.5 with a 1 mol/L hydrochloric acid solution to precipitate tetrahydrofolic acid. The precipitate was filtered and dried in a vacuum drying oven for 8 hours to obtain tetrahydrofolic acid.

Tetrahydrofolate was detected using mesitylene glycol as an internal standard, and the yield of tetrahydrofolate was found to be 91%.

Example 4

The other steps were the same as in Example 1, with a reaction time of 24 h and a reaction temperature of 80° C. The pH of the folic acid solution was changed to conduct experiments to verify the effect of the reaction pH on the yield of tetrahydrofolate. The experimental results are shown in FIG1 .

As shown in Figure 1, when the pH is selected as 10, the yield of tetrahydrofolate is only 23%, when the pH is selected as 6, the yield of tetrahydrofolate is 79%, and when the pH is selected as 7, the yield of tetrahydrofolate reaches 81% and reaches a peak value, indicating that the yield of the reaction is highest when the pH is 7.

Example 5

The other steps were the same as in Example 1, and the reaction time was changed to conduct experiments to verify the effect of reaction time on the yield of tetrahydrofolate. The experimental results are shown in FIG2 .

As shown in Figure 2, when the reaction time is 6 hours, the yield of tetrahydrofolate is only 79%, when the reaction time is 12 hours, the yield of tetrahydrofolate is 85%, and when the reaction time is 15 hours, the yield of tetrahydrofolate reaches 90% and reaches a peak value, indicating that the reaction yield is highest when the reaction time is 15 hours.

Example 6

The other steps were the same as in Example 1, and the reaction temperature was changed to conduct experiments to verify the effect of reaction temperature on the yield of tetrahydrofolate. The experimental results are shown in FIG3 .

As shown in Figure 3, when the reaction temperature is 30°C, the yield of tetrahydrofolic acid is only 10%, when the reaction temperature is 50, the yield of tetrahydrofolic acid is only 79%, when the reaction temperature is 60°C, the yield of tetrahydrofolic acid reaches 90%, and when the reaction temperature is 70°C, the yield of tetrahydrofolic acid is 92% and reaches a peak value, indicating that the reaction yield is highest when the reaction temperature is 70°C.

Example 4

The other steps were the same as in Example 1, and the amount of the catalyst Pd/C was changed to conduct experiments to verify the effect of the amount of the catalyst Pd/C on the yield of tetrahydrofolate. The experimental results are shown in FIG4 .

As shown in Figure 4, when the mass of catalyst Pd/C is 0.5% of the mass of folic acid, the yield of tetrahydrofolate is only 13%. When the amount of catalyst is increased, when the mass of catalyst Pd/C is greater than 5% of the mass of folic acid, the yield tends to be stable, and the reaction yield is >90%.

FIG5 is an NMR image of the product tetrahydrofolate, and the results are as follows:

¹ H NMR (400 MHz, DMSO-d6) δ8.10 (d, J = 7.7 Hz, 1H), 7.66 (d, J = 8.5 Hz, 2H), 6.63 (d, J = 8.5 Hz, 2H), 6.42 (s, 1H), 6.18 (s, 1H), 5.74 (s, 2H), 4.35 (ddd, J = 9.7, 7.6, 4.9 Hz, 1H), 3.36 (d, J = 11.3 Hz, 1H), 3.13 (s, 3H), 3.06–2.91 (m, 1H), 2.33 (t, J = 7.5 Hz, 2H), 2.05 (ddd, J = 12.9, 9.4, 5.3 Hz, 1H), 1.93 (ddd, J = 13.8, 9.6, 6.9 Hz, 1H).

The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims (8)

1. A method for preparing tetrahydrofolic acid, comprising the steps of:

Adding a Pd/C catalyst and a folic acid solution into a reaction kettle, filling hydrogen into the reaction kettle, placing the reaction kettle in an environment of 60-80 ℃, carrying out oxidation-reduction reaction on folic acid and hydrogen, and obtaining tetrahydrofolic acid after the reaction is finished;

the reaction equation for preparing tetrahydrofolate is as follows:

wherein, the chemical formula of folic acid is:

The chemical formula of the tetrahydrofolate is as follows:

the Pd/C of the catalyst is 10% Pd/C, and the mass ratio of folic acid to the 10% Pd/C of the catalyst is 100 (5-20);

The reaction time of the folic acid and the hydrogen for oxidation-reduction reaction is 15h;

The pH of the folic acid solution is 6-7.

2. The method for preparing tetrahydrofolate of claim 1, wherein in the step of oxidation-reduction reaction of folic acid with hydrogen, the pressure of the reaction vessel is in the range of 20-65bar.

3. The method for preparing tetrahydrofolic acid of claim 1, wherein the step of obtaining tetrahydrofolic acid after the reaction is completed comprises:

After the reaction is finished, a solution containing the tetrahydrofolic acid is obtained, the pH value of the solution containing the tetrahydrofolic acid is regulated to 3-3.5 by an acid solution, a solution containing the tetrahydrofolic acid sediment is obtained, the solution containing the tetrahydrofolic acid sediment is filtered, the tetrahydrofolic acid sediment is collected, and the sediment is dried, so that the tetrahydrofolic acid is obtained.

4. The method for preparing tetrahydrofolate according to claim 1, wherein the preparation of the folic acid solution comprises the steps of:

Adding solid folic acid into a flask, filling nitrogen or inert gas into the flask to form an anaerobic environment, adding a buffer solution into the flask, stirring uniformly to obtain a mixed solution, and regulating the pH value of the mixed solution to 6-7 by using an alkali solution to obtain a folic acid solution.

5. The method for producing tetrahydrofolate according to claim 4, wherein the pH of the buffer solution is 4 to 10.

6. The method for preparing tetrahydrofolic acid of claim 4, wherein the buffer solution comprises any one of disodium hydrogen phosphate-citric acid buffer solution, disodium hydrogen phosphate-disodium hydrogen phosphate buffer solution, disodium hydrogen phosphate-potassium dihydrogen phosphate buffer solution, barbital sodium-hydrochloric acid buffer solution, tris buffer solution, boric acid-borax buffer solution, glycine-sodium hydroxide buffer solution, borax-sodium hydroxide buffer solution, sodium carbonate-sodium bicarbonate buffer solution, britton-Robinson buffer solution and Tris buffer salt solution.

7. The method for producing tetrahydrofolic acid of claim 4, wherein the alkaline solution comprises any one of NaOH solution and KOH solution.

8. The method for preparing tetrahydrofolate according to claim 4, wherein the buffer solution is used in an amount of 10-15ml/1g solid folic acid.