CN101020630A - Abietic acid preparing process - Google Patents

Abstract

The invention proposes a preparation method of abietic acid. Rosin is catalyzed by hydrochloric acid and microwave chemical reaction method is used to rapidly (1 hour) isomerize abietic acid. Abietic acid is a raw material for the synthesis of fine chemicals.

Description

A kind of preparation method of abietic acid

technical field

The present invention relates to the preparation method of organic compound, more specifically, the present invention relates to a kind of method that adopts microwave chemical reaction to prepare abietic acid.

Background technique

Rosin is an important chemical raw material, which has been widely used in the fields of papermaking, printing, adhesives and daily chemicals. As a mixture, rosin contains various components such as various resin acids, fatty acids and neutral substances. The composition of rosin from different sources will also vary. Usually rosin is applied in the form of mixture. Abietic acid is one of the main components of resin acids in rosin. Because its chemical structure contains carboxyl groups and conjugated double bonds, it is very suitable as a raw material for the synthesis of fine chemicals. And because there are multiple optically active centers in the abietic acid molecule, organic compounds and chiral molecules with biological activity can be selectively synthesized, which also makes the separation and purification method of abietic acid very important and meaningful, because it can be obtained A cheap raw material synthesized from chiral compounds obtained from renewable resources, and because rosin resin is a natural product, generally its derivatives have good ecological performance, which is in line with the "raw material" in the sustainable development of the chemical industry in the 21st century Greening" requirements.

Since the beginning of the last century, many scientists have devoted themselves to the research of resin acid isolation methods in rosin, and introduced a variety of methods. However, the existing methods generally have the disadvantages of large solvent consumption, cumbersome process, many steps, and high cost. In many cases, these methods are only used as the preparation of standard samples for laboratory determination of physical constants, chemical characteristics and gas chromatographic analysis, and industrial production cannot be realized.

According to Wang Linlin's review ("Chemical Progress" 2005.24 (11): 1301 "Isolation and Application of Rosin Resin Acid"), the isolation of abietic acid used sodium salt crystallization method in the early stage, that is, rosin isomerization was made with glacial acetic acid, and rosin was isomerized with glacial acetic acid. The isomerized rosin is recrystallized with acetic acid, converted into sodium abietic acid by adding sodium ethoxide and recrystallized with acetone, and finally hydrolyzed with acetic acid and recrystallized with acetic acid and water to obtain pure abietic acid. This method needs a large amount of acetic acid and ethanol to recrystallize repeatedly, and the yield is very low. The new method uses amine salt instead of sodium salt for recrystallization, isomerizes rosin in hydrochloric acid ethanol solution, evaporates ethanol and water, dissolves in ether, washes and dries, dissolves in acetone, adds dipentylamine to generate abietic acid di Amylamine salt, neutralized with glacial acetic acid in ethanol solution, washed with water to obtain crude abietic acid, and then recrystallized with ethanol to obtain pure abietic acid crystals.

There are following deficiencies in the existing abietic acid isolation method:

1. Although the amination reaction has high reaction selectivity at low temperature, the reaction and crystallization speed is slow; at high temperature, the reaction speed is fast but the selectivity is low.

2. The solvent consumption is large, the process is cumbersome, there are many steps, and the cost is high.

Contents of the invention

The purpose of the present invention is to provide a method for preparing abietic acid by microwave chemical reaction in order to overcome the deficiencies in the prior art. In order to solve the problems of the technologies described above, the present invention is achieved through the following technical solutions: 1. Rosin is mixed with 95% ethanol and concentrated hydrochloric acid, under nitrogen protection, in the container of reflux device. 2. Put the container into a microwave oven (or microwave reactor) and adjust the microwave power to 320-640W, preferably 640W; or put it into a microwave-assisted synthesis/extraction reactor with a reaction temperature of 81-86°C and irradiate to reflux The reaction time is 0.5～3.0h, preferably 1h. 3. Put the solution obtained after the microwave reaction into the refrigerator to cool, the cooling temperature is 0°C to -7°C, preferably -7°C, and the cooling time is 2 to 12h, preferably 12h, to obtain the crude product. 4. Purify the crude product with acetone and recrystallize three times to obtain 96% abietic acid product.

Compared with the prior art, the present invention has the following advantages:

1. The isomerization reaction of resin acid in rosin adopts microwave chemical method, and the reaction time is short (60 minutes), which saves energy and improves production efficiency.

2. The pure abietic acid product can be obtained only through four-step reaction or recrystallization, and the steps are few, which improves the yield.

3. It is not necessary to use dipentylamine salt for separation, and both ethanol and acetone can be recycled, which is beneficial to reduce costs and protect the environment.

4. The purity and yield of the product are high, and industrialized production can be implemented.

Description of drawings

Fig. 1 is the ultraviolet spectrogram of the product abietic acid of the inventive method.

Fig. 2 is the infrared spectrogram of the product abietic acid of the inventive method.

Fig. 3 is the liquid phase chromatogram of the product abietic acid of raw material rosin and the inventive method, and upper figure is the liquid phase chromatogram of raw material rosin; Lower figure is the liquid phase chromatogram of the product of the inventive method.

Fig. 4 is the chlorine phase chromatography-mass spectrometry analysis result of the product abietic acid of the inventive method.

Fig. 5 is the mass spectrogram of the main peak in Fig. 4, and the mass spectrometry retrieval result is methyl abietate, content 96%.

Detailed ways

The invention uses microwave chemical method to quickly realize the rapid isomerization of resin acid in rosin.

The main component of rosin is resin acid. The general chemical formula of resin acid is C ₂₀ H ₃₀ O ₂ , including abietic acid type and pimaric acid type, etc. The specific structural forms are as follows:

Abietic resin acid

Abietic acid L-pimaric acid Neoabietic acid Longleaf abietic acid

Pimaric acid type resin acid

                                             

Dehydrogenated, hydrogenated resin acids

                                                                                                       

The content of abietic acid is the highest in rosin. Isomerization reaction will take place between various resin acids at high temperature (above 155°C) or in the presence of acid, and the product is mainly abietic acid (Ren Tianrui, Li Yonghong, Rosin Chemistry and Its Application, Chemical Industry Press, Beijing, 2006.1 P57-61). Microwaves can also promote the formation of abietic acid from resin acids, and because microwave chemistry is based on the internal heating of polar molecules by microwaves, it has high thermal efficiency, fast response, and no hysteresis. In addition, due to the direct action of the electromagnetic field on the reactant molecules, it can change the kinetics of the reaction and reduce the activation energy of the reaction, so it can promote the rapid transformation of resin acid to abietic acid.

The raw materials used in the preparation method of the present invention are shown in the table below:

serial number raw material name level Manufacturer 1 Rosin Special grade, acid value 170(mg KOH/g) Wuzhou Rosin Factory 2 hydrochloric acid AR Guangxi Normal University Chemical Reagent Factory 3 95% ethanol AR New fine chemical plant in Guangzhou 4 Absolute ethanol AR New fine chemical plant in Guangzhou

The used equipment of preparation method of the present invention, the name of instrument, model, manufacturer are as follows:

serial number Equipment, instrument name model Production plant name 1 Microwave Assisted Synthesis/Extraction Reactor (Microwave Reactor for short) MAS-1 Shanghai Xinyi Microwave Chemical Technology Co., Ltd. 2 Household microwave oven (with a round hole on the top for WD800B Galanz Microwave Appliance Co., Ltd.

connected to the reflux condenser) manage 3 Round-bottomed flask 500ml 4 UV-visible spectrophotometer GBC916 GBC Instruments Australia 5 Fourier Infrared Spectrometer Mmagna 550 Nicholas Instruments Inc. 6 Liquid chromatography PE220 7 Automatic indicating polarimeter WZZ-1 Shanghai Precision Technology Instrument Co., Ltd. 8 Chlorine Chromatography-Mass Spectrometry PEClarus500 American PE Instrument Company

The preparation method of abietic acid of the present invention is as follows:

Add super-grade rosin to a 500mL round-bottomed flask filled with nitrogen, then add 95% ethanol, dissolve it for a while, transfer it into concentrated hydrochloric acid with a pipette, put it into a microwave reactor or a modified household microwave oven after mixing, and adjust the microwave The power is 320-640W, and it is irradiated and refluxed for 0.5-3.0 hours under the protection of nitrogen, or placed in a microwave reactor, and the reaction temperature is 81-86°C. The resulting solution was plugged with a stopper and placed in a refrigerator at 0 to -7°C for 2 to 12 hours. After filtration, the crude product was obtained. The crude product was added to acetone, heated in a water bath and magnetically stirred. The temperature of the water bath is 60°C, and the conical flask is connected with a condenser. After the product is dissolved, filter it while it is hot, and then put the filtrate in the refrigerator at 0-7°C for 2-12 hours. After suction filtration, recrystallize twice with acetone in the same way to obtain a purified milky white crystal product. The product is measured with a UV-Vis spectrophotometer and a Fourier infrared spectrometer, and the results are shown in Figure 1 and Figure 2 respectively, which is consistent with the value of abietic acid in the literature. Analyze the liquid chromatogram of raw material rosin and the method product of the present invention with liquid chromatography as shown in Figure 3: the upper figure is the liquid chromatogram of rosin, and the lower figure is the liquid chromatogram of the method product of the present invention, and the two spectrograms compare Visible method product miscellaneous peak of the present invention is few, is mainly the chromatographic peak of abietic acid. The content of the inventive method product abietic acid is measured with gas chromatography-mass spectrometry, analysis result as shown in Figure 4 and Figure 5, analysis condition: PE-5 capillary column (30m * 0.25mm), initial column temperature 60 ℃ , 0.10min; rise to 240℃ at a rate of 3℃ and keep for 10min. After the sample was dissolved in absolute ethanol, phenolphthalein was used as the indicator, and tetramethylammonium hydroxide was dropped to pink (methylation), and then the sample was analyzed. The front peaks in the figure are all peaks of solvent and phenolphthalein impurities, and only the peak of dehydroabietic acid methyl ester appears at retention time 55.14min. The normalized analysis abietic acid content was 96.8%.

The influence of reaction conditions on product performance is as follows:

Due to the difference in structure, the specific optical rotation of different resin acids is different, and wherein the specific optical rotation of abietic acid is the most negative (Ren Tianrui, Li Yonghong, "Rosin Chemistry and Its Application", "Chemical Industry Press", Beijing, 2006.1 P59). Therefore, the content of abietic acid can be determined by measuring the specific rotation of the isomerization product. The higher the content of abietic acid, the more negative the specific rotation of the sample will be.

In past studies, hydrochloric acid, acetic acid, sulfuric acid, etc. have been used as catalysts for the isomerization of rosin. But with hydrochloric acid as catalyst, the content of abietic acid in the product is the highest (Ren Tianrui, Li Yonghong, Rosin Chemistry and Its Application, Chemical Industry Press, Beijing, 2006.1 P57-61). Therefore, we chose to use hydrochloric acid as the catalyst.

Influence of the amount of hydrochloric acid added on the optical rotation of the product

According to the aforementioned method, hydrochloric acid of different additions is used to carry out rosin isomerization, and the optical rotation of the resulting solution is measured with an automatic indicating polarimeter, and the results are shown in Table 1:

Table 1 The effect of the addition amount of concentrated hydrochloric acid on the specific optical rotation of the product

Amount of hydrochloric acid added (mL) 0 0.5 1.0 2.0 4.0 Specific rotation +7.56 -39.48 -40.95 -33.18 -24.99

When concentrated hydrochloric acid is not added, the isomerization of resin acid is mainly carried out by thermal isomerization, the result is very different from the result in the presence of acid, and the specific rotation of the product is positive. This indicates that the content of abietic acid in the isomerization product is not high when no acid is added. And when continue to increase the amount of hydrochloric acid added, the specific rotation of the product gradually decreased. This may be because the degree of esterification reaction under microwave irradiation increases after the addition of hydrochloric acid increases. The isomerization reaction of rosin ester is much slower than that of rosin acid. As can be seen from Table 1, when the hydrochloric acid addition is 1.0mL, the specific optical rotation of the product is the most negative. Therefore, the isomerization effect is the best at this addition amount.

Influence of Microwave Radiation Power on Optical Rotation of Products

According to the aforementioned method, the influence of different microwave irradiation powers on the specific optical rotation of the product was studied and measured with an automatic indicating polarimeter. The results are shown in Table 2.

Table 2 Effect of microwave irradiation power on product specific rotation

Microwave irradiation power (W) 320 480 640 800 Specific rotation -38.05 -38.64 -40.95 -28.14

It can be seen from Table 2 that with the increase of microwave power, the specific optical rotation of the product becomes more negative, indicating that increasing microwave power is beneficial to isomerization. This is consistent with the conclusion that increasing the isomerization reaction temperature can accelerate the reaction. From 320 to 640W, the microwave irradiation power has little effect on the optical rotation. Under 800W microwave irradiation, the specific optical rotation of the product is obviously reduced. The reason should be the same as that in the previous section, which is due to the adverse effect of the esterification reaction on the isomerization reaction. The isomerization effect is the best when the microwave irradiation power is 640W.

Effect of Reaction Time on Optical Rotation of Products

Literature results show that the isomerization reaction generally takes 3 hours or longer (Ren Tianrui, Li Yonghong, Rosin Chemistry and Its Application, Chemical Industry Press, Beijing, 2006.1 P57-61). We used an automatic indicating polarimeter to measure the specific rotation of the product in the microwave isomerization reaction system with different microwave irradiation time, and the results are listed in Table 3

Table 3 Effect of microwave irradiation time on product optical rotation

Microwave irradiation time (h) 0.5 1 2 3 5 Specific rotation -24.28 -40.95 -39.90 -38.22 -37.17

According to the literature, it takes 3 hours for the isomerization reaction to reach equilibrium under conventional conditions. The results in Table 3 show that the isomerization reaction is significantly accelerated under microwave irradiation, and the specific optical rotation of the product reaches the lowest value after 1 hour of reaction, and the specific optical rotation does not change much within 1 to 3 hours. While increasing the irradiation time, the specific optical rotation of the reaction solution decreased instead. This may be related to the effect of the esterification reaction product on the isomerization balance.

Product Recrystallization Research

The main product of the isomerization reaction is abietic acid, but it still contains a small amount of other resin acids and impurities. It is expected to improve the purity of the product through recrystallization. Commonly used solvents for recrystallization of abietic acid are acetic acid, ethanol and acetone. Due to the low boiling point of acetone, it will not cause the isomerization of abietic acid, and it is easy to operate and recover the solvent, and the obtained crystal form is also good, so acetone is selected for recrystallization and purification in this paper. The experimental results show that after three times of recrystallization, the specific rotation of the product does not change much. The product is thus finally recrystallized three times. The total yield of abietic acid purification is between 15% and 25%, the specific rotation of the product is -95°, and the melting point is 170°C, which is close to the literature value (-105°C, 170°C). The content of abietic acid in the product measured by the gas spectrometer is 96%, and the main impurity is dehydroabietic acid.

The yield of product abietic acid in the experiment is closely related to the quality of raw material rosin. The higher the resin acid content in the raw material, the fewer the oxidation products and the higher the yield of abietic acid.

Concrete experimental mode of the present invention:

Embodiment 1: Add 50.0g extra-grade rosin in a 500mL garden bottom flask filled with nitrogen, then add 83mL of 95% ethanol, dissolve it slightly and move into 1.00mL concentrated hydrochloric acid with a pipette, mix it and put it into the modified household In a microwave oven, under the protection of nitrogen, the reflux reaction was irradiated with a power of 640W for 1 hour. The resulting solution was plugged with a stopper and placed in a refrigerator at -7°C for 12 hours. After filtration, 38 g of a crude product was obtained. Add 3 times the amount (mL/g) of acetone to the crude product, heat it in a water bath and stir it electromagnetically. The temperature of the water bath is 60°C, and the conical flask is connected with a condenser. After the product is dissolved, filter it while it is hot, then put the filtrate in the refrigerator and place it at -7°C for 12 hours, and get 27.6 g of a recrystallized product after suction filtration. Recrystallize twice with acetone in the same way to obtain the product of the present invention. 13.9 g of milky white crystals of abietic acid, the content of abietic acid detected by gas chromatography-mass spectrometry is ≥96%.

Example 2: Add 50.0g of super-grade rosin to a 500mL round-bottomed flask filled with nitrogen, then add 83mL of 95% ethanol, dissolve it for a while and then transfer 1.00mL of concentrated hydrochloric acid with a pipette, mix it and put it into a modified household microwave oven , reflux reaction with 640W power irradiation for 1 hour under the protection of nitrogen, the resulting solution was plugged with a stopper and placed in a refrigerator at -7°C for 2 hours, and 21 g of crude product was obtained after filtration. Add 3 times the amount (mL/g) of acetone to the crude product, heat it in a water bath and stir it electromagnetically. The temperature of the water bath is 60°C, and the conical flask is connected with a condenser. After the product is dissolved, filter it while it is hot, then put the filtrate in the refrigerator and place it at -7°C for 2 hours, and get 10.1 g of a recrystallized product after suction filtration. Recrystallize twice with acetone in the same way to obtain the product of the present invention. 6.5 g of milky white crystals of abietic acid, the content of abietic acid detected by gas chromatography-mass spectrometry is ≥96%.

Example 3: Add 50.0g of super-grade rosin to a 500mL round-bottomed flask filled with nitrogen, then add 83mL of 95% ethanol, dissolve it for a while and move into 5.00mL of concentrated hydrochloric acid with a pipette, mix it and put it into a modified household microwave oven , reflux reaction with 640W power irradiation for 1 hour under the protection of nitrogen, the resulting solution was plugged with a stopper and placed in a refrigerator at -7°C for 12 hours, and 29.3 g of crude product was obtained after filtration. Add 3 times the amount (mL/g) of acetone to the crude product, heat it in a water bath and stir it electromagnetically. The temperature of the water bath is 60°C, and the conical flask is connected with a condenser. After the product is dissolved, filter it while it is hot, then put the filtrate in the refrigerator and place it at -7°C for 2 hours, and get 16.9 g of a recrystallized product after suction filtration. Recrystallize twice with acetone in the same way to obtain the product of the present invention. 10.5 g of milky white crystals of abietic acid, the content of abietic acid detected by gas chromatography-mass spectrometry is ≥ 96%.

Embodiment 4: Add 50.0g extra-grade rosin in the 500mL round bottom flask full of nitrogen, add 83mL 95% ethanol again, after dissolving slightly, move into 1.00mL concentrated hydrochloric acid with pipette, put into microwave reactor after mixing , under the protection of nitrogen, the temperature of the reaction solution was set at 83°C to reflux for 1 hour. The resulting solution was plugged with a stopper and placed in a refrigerator at -7°C for 12 hours. After filtration, 35.8 g of a crude product was obtained. Add 3 times the amount (mL/g) of acetone to the crude product, heat it in a water bath and stir it electromagnetically. The temperature of the water bath is 60°C, and the conical flask is connected with a condenser. After the product dissolves, filter it while it is hot, then put the filtrate in the refrigerator and place it at -7°C for 12 hours, and get 23.0 g of a recrystallized product after suction filtration. Recrystallize twice with acetone in the same way to obtain the product of the method of the present invention 15.4 g of milky white crystals of abietic acid, the content of abietic acid detected by gas chromatography-mass spectrometry is ≥96%.

Embodiment 5: Add 50.0g extra-grade rosin in the 500mL garden bottom flask that is filled with nitrogen, add 83mL 95% ethanol again, after dissolving slightly, move into 1.00mL concentrated hydrochloric acid with pipette, put into the household after mixing In a microwave oven, under the protection of nitrogen, the reflux reaction was irradiated with 320W power for 1 hour. The resulting solution was plugged with a stopper and placed in a refrigerator at -7°C for 12 hours. After filtration, 37.2 g of a crude product was obtained. Add 3 times the amount (mL/g) of acetone to the crude product, heat it in a water bath and stir it electromagnetically. The temperature of the water bath is 60°C, and the conical flask is connected with a condenser. After the product is dissolved, filter it while it is hot, then put the filtrate in the refrigerator and place it at -7°C for 12 hours, and get 22.0 g of a recrystallized product after suction filtration. Recrystallize twice with acetone in the same way to obtain the product of the method of the present invention 12.5 g of milky white crystals of abietic acid, the content of abietic acid detected by gas chromatography-mass spectrometry is ≥ 96%.

Embodiment 6: in the 500mL garden bottom flask that is filled with nitrogen, add 50.0g extra-grade rosin, then add 83mL 95% ethanol, after dissolving slightly, move into 1.00mL concentrated hydrochloric acid with pipette, put into microwave reactor after mixing , under the protection of nitrogen, the temperature of the reaction solution was set at 85°C for reflux reaction for 1 hour. The resulting solution was plugged with a stopper and placed in a refrigerator at -7°C for 12 hours. After filtration, 34.4 g of a crude product was obtained. Add 3 times the amount (mL/g) of acetone to the crude product, heat it in a water bath and stir it electromagnetically. The temperature of the water bath is 60°C, and the conical flask is connected with a condenser. After the product is dissolved, filter it while it is hot, then put the filtrate in the refrigerator and place it at -7°C for 12 hours, and get 20.1 g of a recrystallized product after suction filtration. Recrystallize twice with acetone in the same way to obtain the product of the method of the present invention 11.0 g of milky white crystals of abietic acid, the content of abietic acid detected by gas chromatography-mass spectrometry is ≥96%.

Claims (3)

1. a preparation method of abietic acid is characterized in that: comprise the following steps: (1) rosin is mixed with 95% ethanol and concentrated hydrochloric acid under nitrogen protection, in the container of reflux device; (2) container is placed Put it into a microwave oven or a microwave reactor, adjust the microwave power to 320-640W, and the irradiation reflux reaction time is 0.5-3.0h; ~3.0h; or use a microwave-assisted synthesis/extraction reactor, the reaction temperature is 81-86°C, and the irradiation time is 1h; (3) The solution obtained after the microwave reaction is cooled in a refrigerator at a cooling temperature of 0°C--7°C, and cooled After 2-12 hours, the crude product was obtained. (4) The crude product was recrystallized three times with acetone to obtain 96% abietic acid product. 2. abietic acid preparation method according to claim 1 is characterized in that: described microwave power is 640W, and the irradiation reaction time is 1h. 3. the preparation method of abietic acid according to claim 1 is characterized in that: described cooling temperature is-7 ℃, cooling time 12h.

Images