JP5458430B2 - Purification method of lignophenol derivatives - Google Patents

Description

  The present invention relates to a method for purifying a biomass-derived phenolic lignin polymer (hereinafter referred to as lignophenol derivative).

  Research and development has been actively conducted to effectively utilize biomass-derived lignin such as wood, grass, waste wood, and building waste materials that have been disposed of after being discarded or incinerated. As a technique using lignin, for example, Patent Document 1 discloses a method for producing a lignophenol derivative in which plant-derived lignin is reacted with a phenol derivative and an acid to convert to a lignophenol derivative and separated and purified. .

The production of the lignophenol derivative and the purification method thereof comprise the following steps.
(1) adding a phenol derivative (specifically p-cresol) and an acid (specifically sulfuric acid) to biomass which is a lignocellulosic material, solvating lignin with a phenol derivative and hydrolyzing a carbohydrate;
(2) a step of separating the phenol derivative liquid from the acid to obtain a phenol derivative layer;
(3) The obtained phenol derivative layer is dropped into a lignophenol derivative poor solvent (specifically, aliphatic hydrocarbons or aliphatic ethers), and the lignophenol derivative is separated from the phenol derivative to form an insoluble category. Recovering step (primary purification),
(4) The step of recovering the lignophenol derivative by separating the phenol derivative contained in the insoluble section by dissolving the obtained insoluble section in acetone and adding it dropwise to the poor solvent of the lignophenol derivative (secondary purification) .

The obtained lignophenol derivative can be applied to various materials and dried to form a molded body. Further, since the lignophenol derivative is soluble in acetone, there is an advantage that it can be easily recovered even when the molded body is unnecessary, and can be repeatedly used.
Furthermore, for applications other than paints other than molded articles, a wide range of applications to electronic and electrical materials, medicines and the like are expected.

Japanese Patent Laid-Open No. 02-233701

  The present inventors have examined the practical application of a method for producing a lignophenol derivative from a lignocellulosic material. In order to scale up from a small experimental level to practical use, it is necessary to reduce the amount of solvent used in the process. For example, when the amount of cresol, which is a phenol derivative, is reduced, the concentration of the lignophenol derivative contained in the phenol derivative solution is increased, and thus the viscosity is increased. When the viscosity is increased, it takes a long time for the reaction solution to stand to separate the phenol derivative layer and the acid layer from each other, and it is difficult to separate the solution alone, so that it remains in the phenol derivative layer. We faced the problem of increasing the amount of acid. At the laboratory level, this problem has been ignored because the reaction solution can be immediately dropped into the parent solvent or poor solvent of the lignophenol derivative to quickly remove the acid from the reaction system. Although high-speed centrifugation can be performed instead of stationary separation, it is not preferable because it leads to an increase in the size of the apparatus and an increase in initial cost.

If the amount of acid remaining in the phenol derivative layer is large, it is necessary to repeat the above-described primary purification and secondary purification operations several times. The amount of the poor solvent used can be the amount of phenol derivative or the amount of acetone in one operation. It will be 15-20 times as much. An increase in the operation of using a large amount of a poor solvent is not preferable from the viewpoint of safety and cost.
Further, if an acid stays in the phenol derivative solution or the phenol derivative layer, the molecular weight of the lignophenol derivative proceeds, which is not desirable when a high molecular weight lignophenol derivative is desired.

  An object of the present invention is to provide a method for efficiently performing separation and purification without increasing the amount of an organic solvent used in the separation and purification of a lignophenol derivative.

In order to achieve the above object, the method for purifying a lignophenol derivative of the present invention comprises a step of contacting a phenol derivative solution containing a lignophenol derivative and an acid with water, and treating the resulting treatment solution with a water-insoluble polar solvent. Separating the water-insoluble polar solvent layer,
Adding a water-insoluble polar solvent layer to the poor solvent for the lignophenol derivative and separating the precipitate.

  The purification method of the present invention does not require repeated purification of a lignophenol derivative using an organic solvent, so that the amount of the organic solvent used can be reduced, and the process of converting lignin into a lignophenol derivative Can be efficiently recovered and reused.

It is a flowchart which shows the process of the purification method of the lignophenol derivative of this invention. It is a figure which shows the analysis result by GPC (gel permeation chromatography) of the 1st precipitation of Example 1. FIG. It is a figure which shows the GPC analysis result of the 2nd deposit of Example 2. FIG. It is a figure which shows the result of the GPC analysis which shows a time-dependent change of the lignophenol derivative of Example 3. It is a figure which shows the result of the GPC analysis which shows a time-dependent change of the lignophenol derivative (treatment on the day) of Example 4. It is a figure which shows the result of the GPC analysis which shows a time-dependent change of the lignophenol derivative (methyl ethyl ketone extraction process 15 days after) of Example 4.

Hereinafter, the present invention will be described in detail.
[Embodiment 1]
As shown in FIG. 1, the method for purifying lignophenol derivatives of this embodiment includes the following steps.
(1) A step of contacting a phenol derivative solution containing a lignophenol derivative and an acid with water,
(2) treating the obtained treatment liquid with a water-insoluble polar solvent and separating the water-insoluble polar solvent layer; and (3) adding the water-insoluble polar solvent layer to the lignophenol derivative poor solvent, The process of separating things.

  A lignophenol derivative is a compound having a 1,1-bis (aryl) propane-2-O-aryl ether type structure in which a phenol derivative is bonded to C1 (benzyl position) of a phenylpropane skeleton. By impregnating the solvent in which the phenol derivative is dissolved in the material and then mixing the acid, the composite state of lignocellulose is relaxed, and at the same time, the phenol derivative is bound to C1 (benzyl position) of the phenylpropane skeleton of lignin. Can be obtained. Here, the acid may be an acid used for hydrolysis of biomass, and for example, sulfuric acid is generally used. Instead of lignocellulosic material, lignin separated from cellulose may be contacted with a phenol derivative.

  The phenol derivative is brought into contact with the biomass in a liquid state. As a phenol derivative, p-cresol is often used, but as a phenol derivative other than p-cresol, phenol, m (meth) -cresol, o (ortho) -cresol, anisole, 2,4-dimethoxyphenol, 2,6-dimethoxyphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, propylphenol, i-propylphenol, tert-butylphenol, catechol, resorcinol, pyrogallol, phloroglucinol, bisphenol, vanillin, syringol, Any of guaiagol, ferulic acid, coumaric acid, or a combination thereof can be used.

  The acid is an inorganic acid such as hydrochloric acid or sulfuric acid, and sulfuric acid is desirable.

  The phenol derivative solution containing the lignophenol derivative contains a low molecular compound such as a lignophenol derivative and a lignophenol derivative fragment, a phenol derivative, and an acid.

  A phenol derivative solution containing a lignophenol derivative, a phenol derivative and an acid is separated into a layer of a phenol derivative solution containing a lignophenol derivative (hereinafter referred to as a phenol derivative layer) and an acid liquid layer by liquid layer separation. Furthermore, the separated lignophenol derivative layer may be further subjected to a centrifugal separation treatment. In other words, in this example, the phenol derivative solution refers to a phenol derivative solution containing a phenol derivative and an acid, regardless of treatment such as liquid layer separation or centrifugation.

When the concentration of the lignophenol derivative in the phenol derivative solution increases, the viscosity of the solution increases and the amount of acid mixed into the phenol derivative layer increases. Even if the acid present in the phenol derivative solution is separated from the phenol derivative layer by liquid layer, it is difficult to eliminate the amount of acid mixed into the phenol derivative layer. If the amount of acid remaining in the phenol derivative layer is large, not only will it be difficult to reuse the phenol derivative, but it will also adversely affect the recovery and reuse of the poor solvent due to acid mixing in the poor solvent used in the purification process. This is not preferable.
In addition, the presence of acid in the phenol derivative solution and the phenol derivative layer has a problem that the lignophenol derivative is likely to be reduced in molecular weight.

In order to remove the acid mixed in the phenol derivative layer, first, the phenol derivative solution containing the lignophenol derivative is contacted with water. Specific examples of the contact treatment include the following operations.
(1) A phenol derivative solution is dropped into water and suspended to obtain an aqueous dispersion.
(2) The phenol derivative solution is washed with water.

In order to make the phenol derivative solution into an aqueous dispersion, more water is required than the phenol derivative solution, but in the case of water washing, it is possible to reduce the amount of water by repeatedly washing with less water. .
Moreover, the acid brought into contact with the phenol derivative solution may be an alkaline aqueous solution to neutralize the acid.

  Next, a water-insoluble polar solvent is added to the treatment solution that has been contact-treated with water. The water-insoluble polar solvent is a solvent that can dissolve the lignophenol derivative and easily separates into water. Examples of such a solvent include methyl ethyl ketone, chloroform, dichloromethane, ethyl acetate, ethers, toluene, and benzene. Considering the solubility and hydrophobicity of the lignophenol derivative, methyl ethyl ketone is preferred.

  By this operation, the treatment liquid is separated into an aqueous layer and a water-insoluble polar solvent layer. The water-insoluble polar solvent layer contains a phenol derivative solution containing a lignophenol derivative, but no acid. Therefore, the lignophenol derivative is not affected by the acid. Moreover, it is possible to suppress sulfonation of a phenol derivative by removing an acid.

  After separating the water-insoluble polar solvent layer, the solution is added dropwise to the poor solvent for the lignophenol derivative to obtain the lignophenol derivative as a precipitate.

The inventors have found that the solvent solubility of lignophenol derivatives is in the following order.
Strong alkaline solution> Alkyl ketones such as acetone and methyl ethyl ketone> Aprotic polar solvents such as dimethylformamide (DMF) and N-methylpyrrolidone (NMP)> Cyclic ethers such as tetrahydrofuran (THF) and dioxane> Pyridine Heterocyclic compounds> alcohols such as ethanol and cellosolve> asymmetric ethers such as tert-butyl methyl ether (TBME) and cyclopentyl methyl ether (CPME)> symmetric alkyl ethers such as diethyl ether, dipropyl ether and diisopropyl ether > Toluene or a mixed solvent of xylene and hexane> Aromatic hydrocarbons such as benzene and toluene> Aliphatic hydrocarbons such as hexane, heptane, and octane.

  As the poor solvent for the lignophenol derivative, asymmetric ethers, symmetric alkyl ethers, cyclic hydrocarbons, linear hydrocarbons, and esters can be used. Specific examples include diisopropyl ether, diethyl ether, n-hexane, pentane, benzene, toluene, and ethyl acetate, and diisopropyl ether is preferred. In addition, it is a conventional means in this field to mix the above-mentioned poor solvent and change the polarity, and a combination of solvents having different polarities may be used as the poor solvent.

  When methyl ethyl ketone is used as the water-insoluble polar solvent, a combination of methyl ethyl ketone and liquid linear hydrocarbon is preferable.

  The precipitated lignophenol derivative is recovered by centrifugation or the like. The obtained lignophenol derivative may be dissolved in acetone or methyl ethyl ketone and further re-precipitated by dropping it into a mixed solvent of diisopropyl ether or methyl ethyl ketone and liquid linear hydrocarbon in order to increase the degree of purification. .

  The methyl ethyl ketone, the poor solvent, and the phenol derivative can be separated by distillation.

10 ml of p-cresol was added to 1 g of cypress defatted wood flour, 10 ml of 72% H ₂ SO ₄ was added thereto, and the mixture was stirred at 30 ° C. for 1 hour. Ten minutes before stopping the reaction, 5 ml of m, p-cresol was added and stirred. After completion of the reaction, the mixture was centrifuged to separate into a cresol layer and a sulfuric acid layer. When the cresol layer was dropped into 25 ml of water, it was suspended in a light pink color.

When 10 ml of methyl ethyl ketone was added to the suspension and allowed to stand for a while, it was separated into a methyl ethyl ketone layer containing a lignophenol derivative and an aqueous layer. The upper methyl ethyl ketone layer was added dropwise to diisopropyl ether to obtain a pale pink white precipitate. This precipitate was dissolved in acetone, and the soluble fraction was concentrated and then dropped again into diisopropanol to obtain 0.282 g of a precipitate (lignophenol derivative). This precipitate was 104% per lignin.
FIG. 2 shows the GPC analysis result of the first product precipitate, and FIG. 3 shows the GPC analysis result of the second precipitate.

  Cypress wood flour was treated under the same conditions as in Example 1. The obtained cresol layer was allowed to stand at room temperature for 0 to 7 days, the lignophenol derivative was purified from the cresol layer, and the change in the average molecular weight was examined. Diisopropyl ether was used as the purification solvent. The result of GPC analysis of the obtained lignophenol derivative is shown in FIG.

  Centrifugation was performed after the phase separation treatment, and the weight-average molecular weight of the lignophenol derivative immediately purified was about 14,000, but decreased to about 8500 after standing at room temperature for 3 hours. After 15 hours, the molecular weight had dropped to about 4200. The change over time was examined until the seventh day, but after the second day, the molecular weight was about 3500 and no further reduction in molecular weight was observed.

  A cresol layer (1000 g) obtained by converting birch wood flour in a continuous plant resource conversion plant was placed in a 5 liter separatory funnel, and 250 g of ion-exchanged water was added thereto and stirred slowly. Next, 1 liter of methyl ethyl ketone was added, stirred for 5 minutes, allowed to stand for 1 hour, and separated. About 1470 g of methyl ethyl ketone layer and about 500 g of aqueous layer were recovered. The sulfuric acid concentration in the aqueous layer was about 36%, and most of the sulfuric acid contained in the cresol layer was transferred to the aqueous layer.

To the methyl ethyl ketone layer, 337 g of a 15% aqueous sodium carbonate solution was added, stirred for 5 minutes, allowed to stand for 1 hour and separated.
To the methyl ethyl ketone layer, 250 g of ion exchange water was added, stirred for 5 minutes, allowed to stand for 1 hour and separated. Further, 250 g of ion-exchanged water was added, stirred for 5 minutes, allowed to stand for 1 hour and separated. The washed methyl ethyl ketone layer was concentrated under reduced pressure to recover the methyl ethyl ketone layer.
The methyl ethyl ketone layer was concentrated and 300 ml was dropped to 2900 ml of a heptane / methyl ethyl ketone 70/30 mixture. The insoluble fraction was collected by vacuum filtration and washed with heptane. This was dried to obtain 65 g of purified lignophenol derivative. This lignophenol derivative contained about 13% cresol.

  The obtained lignophenol derivative was dissolved in 250 ml of methyl ethyl ketone, and the insoluble fraction was removed by filtration. The filtrate was added dropwise to 1450 ml of a heptane / methyl ethyl ketone 80/20 mixture. The insoluble fraction was collected by vacuum filtration and washed with heptane. This was dried to obtain 37 g of a secondary purified lignophenol derivative.

  The secondary purified lignophenol derivative was dissolved in 316 ml of methyl ethyl ketone, and the insoluble fraction was removed by filtration. The filtrate was added dropwise to 1450 ml of a heptane / methyl ethyl ketone 80/20 mixture. The insoluble fraction was collected by vacuum filtration and washed with heptane. This was dried to obtain 32 g of tertiary purified lignophenol derivative.

  The lignophenol derivative obtained by this purification method had almost the same properties and a slightly higher yield than the solvent purification using diisopropyl ether alone. From these facts, it was possible to improve the safety, recovery rate and cost of handling the solvent.

  Add 100 ml of 72% sulfuric acid to 15 g of cypress wood powder sorbed 3 mol times of p-cresol (10 g as wood flour), stir at 30 ° C. for 60 minutes, and add 80 ml of m, p-cresol 10 minutes before completion. It was. This was centrifuged and the phenol layer was recovered. The phenol layer had less solid content and good separability. As the interface cleaning, 10 ml of m, p-cresol was added to clean the interface. 100 ml of the cresol layer was recovered. This cresol layer was dropped into 600 ml of water. After the dropwise addition, a pale peach white dispersion was obtained. To this, 200 ml of methyl ethyl ketone was added, placed in a separatory funnel and left overnight. The next day, the turbidity of the methyl ethyl ketone layer was reduced. The aqueous layer was removed and 160 ml of methyl ethyl ketone layer was recovered.

  When the sulfuric acid in the cresol layer and the methyl ethyl ketone layer was quantified by ion chromatography, the amount of sulfuric acid in the cresol layer was 9.68%, but no sulfuric acid could be detected from the methyl ethyl ketone layer.

  On the day of treatment, 10 ml of the methyl ethyl ketone layer was dropped into 120 ml of diisopropyl ether to obtain a primary purified lignophenol derivative. The result of GPC analysis is shown in FIG.

  The primary purified lignophenol derivative was dissolved in acetone and then added dropwise to diisopropyl ether to perform secondary purification to obtain 0.125 g of lignophenol derivative.

15 days after the treatment, 10 ml of the methyl ethyl ketone layer was dropped into 120 ml of diisopropyl ether to obtain a primary purified lignophenol derivative. The result of GPC analysis is shown in FIG.
The primary purified lignophenol derivative was dissolved in acetone and then added dropwise to diisopropyl ether for secondary purification to obtain 0.136 g of lignophenol derivative.

When GPC was observed, the lignophenol derivative 15 days after the treatment had a slight variation in the weight average molecular weight and the number of polymer segments decreased, but almost no change was observed.
The yield was almost the same on both the treatment day and the 15th day, and the molecular weight reduction due to the change with time did not progress.

<Comparative example>
In the same manner as in Example 1, 10 ml of p-cresol was added to 1 g of cypress defatted wood flour, and 20 ml of 72% H ₂ SO ₄ was added thereto and stirred vigorously. After stirring for 60 minutes, the mixture was separated into a p-cresol layer and a sulfuric acid layer by centrifugation (3500 / rpm). When the p-cresol layer was dropped into diisopropyl ether, it was in a dispersed state at the beginning of dropping, but immediately formed an oily aggregate and a pale pink white lignophenol derivative could not be obtained. Separation and purification treatment was required.

Claims (4)

Contacting a phenol derivative solution containing a lignophenol derivative and an acid with water to form an aqueous dispersion of the phenol derivative solution ;
Adding a solvent selected from the group consisting of methyl ethyl ketone, chloroform, dichloromethane, ethyl acetate, ethers, toluene and benzene to the aqueous dispersion of the phenol derivative solution, and separating the aqueous layer and the solvent layer ;
Adding the solvent layer into a poor solvent for lignophenol derivatives, and separating the precipitate, the purified how the lignophenol derivative. The method for purifying a lignophenol derivative according to claim 1 , wherein methyl ethyl ketone is added to the aqueous dispersion of the phenol derivative solution . The method for purifying a lignophenol derivative according to claim 1, wherein the contact treatment between the phenol derivative solution and water is a treatment in which the phenol derivative solution is dropped into water. The method for purifying a lignophenol derivative according to claim 1, wherein the contact treatment between the phenol derivative solution and water is a treatment of washing the phenol derivative solution with water.

Images