阅读说明：本技术 具有环状缩醛结构的刚性生物基二醇单体、其制法与应用 (Rigid bio-based diol monomer with cyclic acetal structure, and preparation method and application thereof ) 是由 慎昂 王静刚 张小琴 朱颜柳 戴行 朱锦 于 2021-09-03 设计创作，主要内容包括：本发明公开了一种具有环状缩醛结构的刚性生物基二醇单体、其制法与应用。所述刚性生物基二醇单体的结构式如下式所示：其中,R-(1)包括-H或-OCH-(3),R-(2)包括-H、-OCH-(3)或-OCH-(2)CH-(3)。所述制法包括：使包含苯甲醛类物质、赤藓糖醇、第一有机溶剂和第一催化剂的第一混合反应体系进行第一反应,得到具有环状缩醛结构的中间体；使包含所述中间体、碳酸乙烯酯、第三有机溶剂和第二催化剂的第二混合反应体系进行第二反应,获得具有环状缩醛结构的刚性生物基二醇单体。本发明通过两步反应以高产率制备了一种全新的具有环状缩醛结构的刚性生物基二醇,用作聚合单体合成生物基聚酯和聚氨酯材料,会使得其力学性能和耐热性能有一定提高。(The invention discloses a rigid bio-based diol monomer with a cyclic acetal structure, and a preparation method and application thereof. The rigid bio-based diol monomer has the formula: wherein R is 1 including-H or-OCH 3 ，R 2 including-H, -OCH 3 or-OCH 2 CH 3 . The preparation method comprises the following steps: carrying out a first reaction on a first mixed reaction system containing benzaldehyde substances, erythritol, a first organic solvent and a first catalyst to obtain an intermediate with a cyclic acetal structure; reacting a second mixture comprising the intermediate, ethylene carbonate, a third organic solvent, and a second catalystThe system is subjected to a second reaction to obtain a rigid bio-based diol monomer having a cyclic acetal structure. The invention prepares a brand new rigid bio-based diol with a cyclic acetal structure in high yield through two-step reaction, and the rigid bio-based diol is used as a polymerization monomer to synthesize bio-based polyester and polyurethane materials, so that the mechanical property and the heat resistance of the bio-based polyester and polyurethane materials are improved to a certain extent.)

1. A rigid bio-based diol monomer having a cyclic acetal structure, wherein the bio-based diol monomer has a structural formula as shown in formula I:

wherein R is₁including-H or-OCH₃，R₂including-H, -OCH₃or-OCH₂CH₃。

2. A rigid bio-based diol monomer having a cyclic acetal structure according to claim 1, wherein: the structural formula of the rigid bio-based diol monomer with the cyclic acetal structure comprises at least any one of formulas IV to VII:

3. the method for producing a rigid bio-based diol monomer having a cyclic acetal structure according to claim 1 or 2, comprising:

carrying out a first reaction on a first mixed reaction system containing benzaldehyde substances, erythritol, a first organic solvent, a second organic solvent and a first catalyst to obtain an intermediate with a cyclic acetal structure;

subjecting a second mixed reaction system comprising the intermediate, ethylene carbonate, a third organic solvent and a second catalyst to a second reaction to obtain a rigid bio-based diol monomer having a cyclic acetal structure;

wherein the structure of the benzaldehyde substance is shown as a formula II:

wherein R is₁including-H or-OCH₃，R₂including-H, -OCH₃or-OCH₂CH₃。

4. The production method according to claim 3, characterized in that: the benzaldehyde substance comprises one or more of p-hydroxybenzaldehyde, vanillin, ethyl vanillin and syringaldehyde;

and/or the first organic solvent comprises one or the combination of more than two of tetrahydrofuran, dioxane, diethyl ether, acetone, butanone, N' -dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone; preferably, the second organic solvent comprises any one or a combination of more than two of dichloromethane, trichloromethane, petroleum ether, cyclohexane, methanol, ethanol and ethyl acetate;

and/or the first catalyst comprises at least any one of ferric chloride, indium fluoride and p-toluenesulfonic acid, and is preferably p-toluenesulfonic acid.

5. The production method according to claim 3, characterized in that: the molar ratio of the benzaldehyde substance to the erythritol is 2: 0.9-1.1; and/or the molar ratio of the first catalyst to the benzaldehyde substances is 0.5-5: 100; and/or the mass ratio of the first organic solvent to the benzaldehyde substance is (1-20) to 1; and/or the mass ratio of the second organic solvent to the benzaldehyde substance is (1-20) to 1.

6. The production method according to claim 3, characterized in that: the temperature of the first reaction is 20-150 ℃, preferably 80-120 ℃, and the reaction time is 0.5-72 h, preferably 8-72 h;

and/or the intermediate with the cyclic acetal structure has a structure shown in a formula III:

wherein R is₁including-H or-OCH₃，R₂including-H, -OCH₃or-OCH₂CH₃。

7. The production method according to claim 3, characterized in that: the third organic solvent comprises one or the combination of more than two of tetrahydrofuran, dioxane, diethyl ether, acetone, butanone, N' -dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone; and/or the catalyst comprises any one or the combination of more than two of potassium carbonate, sodium carbonate and sodium bicarbonate.

8. The production method according to claim 3, characterized in that: the molar ratio of the intermediate to the ethylene carbonate is 1: 4-8; and/or the molar ratio of the second catalyst to the intermediate is (0.1-1) to 100.

9. The production method according to claim 3, characterized in that: the temperature of the second reaction is 60-250 ℃, and the reaction time is 0.5-72 h.

10. Use of the rigid bio-based diol monomer having a cyclic acetal structure according to claim 1 or 2 for the synthesis of a bio-based polyester or polyurethane material.

Technical Field

The invention relates to the technical field of chemistry and materials, in particular to a preparation method and application of a rigid bio-based diol monomer with a cyclic acetal structure.

Background

Polymer materials such as polyester and polyurethane are widely and importantly applied in various fields such as agriculture, food, kitchen electricity, medical appliances and the like. In recent years, due to the large consumption of petrochemical resources, bio-based raw materials are receiving more and more attention, bio-based polymer materials are being researched and applied, and diol compounds are one of the most important raw materials for synthesizing polymer materials such as polyester and polyurethane. At present, most of bio-based diol monomers are flexible aliphatic chain structures and lack rigid cyclic structures, and the problems of poor mechanical property, poor heat resistance and the like of polyesters and polyurethanes synthesized by using the flexible bio-based diols as raw materials often occur. Therefore, the synthesis of bio-based diol monomers with rigid structures is an important part of the development of bio-based polymer materials.

Disclosure of Invention

The invention mainly aims to provide a rigid bio-based diol monomer with a cyclic acetal structure, and a preparation method and application thereof, so as to overcome the defects of the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

some embodiments of the present invention provide a rigid bio-based diol monomer having a cyclic acetal structure, the bio-based diol monomer having a structural formula as shown in formula I:

wherein R is₁including-H or-OCH₃，R₂including-H, -OCH₃or-OCH₂CH₃。

Some embodiments of the present invention provide a method of preparing a rigid bio-based diol monomer having a cyclic acetal structure, comprising:

carrying out a first reaction on a first mixed reaction system containing benzaldehyde substances, erythritol, a first organic solvent, a second organic solvent and a first catalyst to obtain an intermediate with a cyclic acetal structure;

subjecting a second mixed reaction system comprising the intermediate, ethylene carbonate, a third organic solvent and a second catalyst to a second reaction to obtain a rigid bio-based diol monomer having a cyclic acetal structure;

wherein the structure of the benzaldehyde substance is shown as a formula II:

wherein R is₁including-H or-OCH₃，R₂including-H, -OCH₃or-OCH₂CH₃。

In some embodiments, the benzaldehyde substance includes any one or a combination of two or more of p-hydroxybenzaldehyde, vanillin, ethyl vanillin, syringaldehyde and the like.

In some embodiments, the intermediate having a cyclic acetal structure has the structure shown in formula III:

wherein R is₁including-H or-OCH₃，R₂including-H, -OCH₃or-OCH₂CH₃。

In some embodiments, the temperature of the first reaction is 20 ℃ to 150 ℃ and the reaction time is 0.5h to 72 h.

In some embodiments, the temperature of the second reaction is 60 ℃ to 250 ℃ and the reaction time is 0.5h to 72 h.

The embodiment of the invention also provides the rigid bio-based diol monomer with the cyclic acetal structure, which is synthesized by the preparation method.

The embodiment of the invention also provides application of the rigid bio-based diol monomer with the cyclic acetal structure in synthesizing bio-based polyester or polyurethane materials.

After the technical scheme is adopted, compared with the prior art, the invention has the beneficial effects that:

1) the invention adopts benzaldehyde substances and erythritol which are sourced from biology as raw materials, and prepares a brand new rigid biology-based diol monomer with a cyclic acetal structure in high yield through two-step reaction;

2) because the alcoholic hydroxyl groups of the diol molecules provided by the invention are primary alcohols, the polymer has good reactivity when being polymerized, and a polymer with high molecular weight is easily obtained. The acetal ring and benzene ring structures in the molecular structure endow the diol molecules with very high rigidity, and when the diol molecules are used as a polymerization monomer to synthesize bio-based polyester and polyurethane materials, the mechanical property and the heat resistance of the materials are improved to a certain extent. Meanwhile, as the acetal structure can be broken under acidic conditions, the rigid diol with the cyclic acetal structure is introduced into the polyester or polyurethane material, and the polymer has better degradability.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a drawing of an embodiment of the present inventionPreparation of intermediate B having a Cyclic Acetal Structure prepared in example 1¹An H-NMR spectrum;

FIG. 2 is a diagram of the preparation of rigid bio-based diol monomers having cyclic acetal structure according to example 1 of the present invention¹H-NMR spectrum.

Detailed Description

As described above, in view of the defects of the prior art, after a great deal of research and creative work, the present inventors have proposed a technical solution of the present invention to improve the comprehensive performance of novel bio-based polyesters and polyurethanes, and successfully synthesized a rigid bio-based diol monomer having a cyclic acetal structure by using a benzaldehyde substance a derived from a bio-based source and erythritol as raw materials. The present invention will be more fully understood from the following detailed description, which should be read in conjunction with the accompanying drawings. Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed embodiment.

The technical solution, its implementation and principles, etc. will be further explained as follows.

One aspect of the embodiments of the present invention provides a rigid bio-based diol monomer having a cyclic acetal structure, which has a structural formula shown in formula I:

wherein R is₁including-H or-OCH₃，R₂including-H, -OCH₃or-OCH₂CH₃。

In particular, in the formula R₁And R₂Combinations in table 1 can be taken, respectively:

TABLE 1

Substituent group	Combination 1	Combination 2	Combination 3	Combination 4
					R1	-H	-H	-H	-OCH3
R2	-H	-OCH3	-OCH2CH3	-OCH3

In some embodiments, the structural formula of the rigid bio-based diol monomer having a cyclic acetal structure includes at least any one of formulas IV to VII:

specifically, since the alcoholic hydroxyl groups of the diol molecules are primary alcohols, the polymerization reaction has good reactivity, and a polymer with high molecular weight is easily obtained. The acetal ring and benzene ring structures in the molecular structure endow the diol molecules with very high rigidity, and when the diol molecules are used as a polymerization monomer to synthesize bio-based polyester and polyurethane materials, the mechanical property and the heat resistance of the materials are improved to a certain extent. Meanwhile, as the acetal structure can be broken under acidic conditions, the rigid diol with the cyclic acetal structure is introduced into the polyester or polyurethane material, and the polymer has better degradability.

Another aspect of the embodiments of the present invention provides a method for preparing a rigid bio-based diol monomer having a cyclic acetal structure, comprising:

carrying out a first reaction on a first mixed reaction system containing benzaldehyde substances, erythritol, a first organic solvent, a second organic solvent and a first catalyst to obtain an intermediate with a cyclic acetal structure;

and (3) carrying out a second reaction on a second mixed reaction system containing the intermediate, the ethylene carbonate, a third organic solvent and a second catalyst to obtain the rigid bio-based diol monomer with the cyclic acetal structure.

In some embodiments, the process for preparing the rigid bio-based diol monomer having a cyclic acetal structure specifically comprises the following steps:

s1, adding the benzaldehyde substance A, erythritol, a first organic solvent, a second organic solvent and a first catalyst into a reactor, and heating for reaction.

S2, after the reaction, separating and purifying the reaction mixture to obtain intermediate B having a cyclic acetal structure.

S3, adding the intermediate B, the ethylene carbonate, the third organic solvent and the second catalyst into the reactor, and heating for reaction.

And S4, stopping stirring after the reaction is finished, and separating and purifying the reaction mixture to obtain the rigid bio-based diol monomer with the cyclic acetal structure.

In some more specific embodiments, the preparation process of the rigid bio-based diol monomer with a cyclic acetal structure specifically comprises the following steps:

s1, adding the benzaldehyde substance A, erythritol, the first organic solvent and the second organic solvent into a reaction container with a stirring device, and adding the first catalyst for reaction.

S2, precipitating and separating the reaction mixture in water to obtain a solid product, washing the solid product with water for three times, and fully drying the solid product to obtain the intermediate B with a cyclic acetal structure.

S3, adding the intermediate B, the ethylene carbonate and the third organic solvent into a reaction vessel with a stirring device, and adding the second catalyst for reaction.

S4, precipitating and separating the reaction mixture in water to obtain a solid product, washing the solid product with water for three times, and fully drying to obtain the rigid bio-based diol monomer with the cyclic acetal structure.

In the present invention, as a preferred technical solution, in step S1, the structural formula of the benzaldehyde substance a is shown as formula II:

wherein R is₁including-H or-OCH₃，R₂including-H, -OCH₃or-OCH₂CH₃。

In particular, in the formula R₁And R₂Combinations in table 1 can be taken, respectively:

TABLE 1

Substituent group	Combination 1	Combination 2	Combination 3	Combination 4
					R1	-H	-H	-H	-OCH3
R2	-H	-OCH3	-OCH2CH3	-OCH3

Specifically, the four combinations of substituents listed in table 1 respectively represent four different benzaldehyde substances, such as any one or a combination of two or more of p-hydroxybenzaldehyde, vanillin, ethyl vanillin, syringaldehyde, and the like, and the four benzaldehyde substances can be obtained from a bio-based source.

Specifically, the reaction equation of step S1 is shown in formula VIII:

in the formula R₁And R₂Combinations in table 1 can be taken, respectively:

TABLE 1

Substituent group	Combination 1	Combination 2	Combination 3	Combination 4
					R1	-H	-H	-H	-OCH3
R2	-H	-OCH3	-OCH2CH3	-OCH3

In the present invention, as a preferable embodiment, in step S1, the molar ratio of the benzaldehyde substance a to erythritol is 2: (0.9-1.1).

In the present invention, as a preferred embodiment, in step S1, the first organic solvent includes an organic solvent for dissolving the benzaldehyde substance a, erythritol and the catalyst, and in consideration of the solubility of erythritol and the catalyst, the first organic solvent is preferably any one or a combination of two or more of tetrahydrofuran, dioxane, diethyl ether, acetone, butanone, N' -dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, and the like, but is not limited thereto.

Furthermore, in consideration of the requirement of proper solid content for organic reaction, the mass ratio of the first organic solvent to the benzaldehyde substance A is (1-20) to 1.

More specifically, as a preferred technical solution, in step S1, in addition to the first organic solvent, a second organic solvent for carrying out water generated by the reaction through a water separator should be included. The second organic solvent is preferably any one or a combination of two or more of dichloromethane, chloroform, petroleum ether, cyclohexane, methanol, ethanol, ethyl acetate, etc., in consideration of the condition of carrying water, but is not limited thereto.

Furthermore, the mass ratio of the second organic solvent to the benzaldehyde substance A is (1-20) to 1 in consideration of the amount of the solvent required for carrying water.

In the present invention, as a preferable embodiment, the first catalyst in step S1 includes any one or a combination of two or more of ferric chloride, indium fluoride, p-toluenesulfonic acid, and the like, and the first catalyst is preferably p-toluenesulfonic acid in consideration of acidity of the first catalyst.

Further, in the present invention, as a preferable technical solution, in consideration of the catalytic efficiency of the catalyst, in step S1, the amount of the first catalyst is 0.5% to 5% of the molar amount of the benzaldehyde substance a, that is, the molar ratio of the first catalyst to the benzaldehyde substance is 0.5 to 5: 100.

In the present invention, as a preferred embodiment, in step S1, the reaction temperature of the reaction (i.e., the first reaction) is 20 to 150 ℃, and the reaction time is 0.5 to 72 hours.

Further, the temperature of the first reaction is 80-120 ℃, and the reaction time is 8-72 h.

In the present invention, as a preferred embodiment, in step S2, the structure of the intermediate B having a cyclic acetal structure is represented by formula III:

in the formula R₁And R₂Combinations in table 1 can be taken, respectively:

TABLE 1

Substituent group	Combination 1	Combination 2	Combination 3	Combination 4
					R1	-H	-H	-H	-OCH3
R2	-H	-OCH3	-OCH2CH3	-OCH3

Specifically, the reaction equation of step S3 is shown in formula IX:

in the present invention, as a preferable embodiment, in step S3, the molar ratio of the intermediate B to ethylene carbonate is preferably 1: (4 to 8) in view of ensuring completion of the hydroxyethylation reaction.

In the present invention, as a preferred embodiment, in step S3, the third organic solvent includes any one or a combination of two or more of tetrahydrofuran, dioxane, diethyl ether, acetone, butanone, N' -dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, and the like, in consideration of the solubility of the intermediate B, ethylene carbonate, and the catalyst, but is not limited thereto.

In the present invention, as a preferable embodiment, in step S3, the second catalyst may include any one or a combination of two or more of potassium carbonate, sodium hydrogen carbonate, and the like, but is not limited thereto.

Further, in step S3, in consideration of the catalytic efficiency of the catalyst, the amount of the second catalyst is preferably 0.1% to 1% of the molar amount of the intermediate B, that is, in other words, the molar ratio of the second catalyst to the intermediate is 0.1 to 1: 100.

In the present invention, as a preferred embodiment, in step S3, the reaction temperature of the reaction (i.e., the second reaction) is 60 to 250 ℃, and the reaction time is 0.5 to 72 hours.

In another aspect of the embodiments of the present invention, there is also provided a use of the rigid bio-based diol monomer having a cyclic acetal structure in the synthesis of a bio-based polyester or polyurethane material.

Furthermore, since the alcoholic hydroxyl groups of the diol molecules are all primary alcohols, the polymerization reaction has good reactivity, and a polymer with high molecular weight is easily obtained. The acetal ring and benzene ring structures in the molecular structure endow the diol molecules with very high rigidity, and when the diol molecules are used as a polymerization monomer to synthesize bio-based polyester and polyurethane materials, the mechanical property and the heat resistance of the materials are improved to a certain extent. Meanwhile, as the acetal structure can be broken under acidic conditions, the rigid diol with the cyclic acetal structure is introduced into the polyester or polyurethane material, and the polymer has better degradability.

According to the technical scheme, in the preparation method, the benzaldehyde substance A and the erythritol are used as raw materials, and the rigid bio-based diol with the cyclic acetal structure is prepared in a high yield through two-step simple chemical reaction. The preparation process has simple process, simple and convenient operation, good controllability and easy implementation, and is suitable for large-scale industrial production. Moreover, the rigid diol has very high bio-based content, the benzaldehyde substance A and the erythritol which are used as raw materials can be prepared from bio-based sources, the ethylene carbonate used for the hydroxyethylation reaction can also be prepared from the bio-based sources, and the synthetic process is very green and environment-friendly and has important significance on resources and environment.

The rigid bio-based diol monomer containing a cyclic acetal structure and the method for preparing the same will be described in further detail with reference to several preferred embodiments and the accompanying drawings, and it is apparent that the embodiments described are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out under conventional conditions or conditions recommended by the manufacturers.

In the following examples, NMR spectra¹H-NMR was measured using a 400AVANCEIII Spectrometer (Spectrometer) from Bruker, 400MHz, deuterated dimethyl sulfoxide (DMSO).

Example 1

S1, adding 0.4mol of vanillin, 0.2mol of erythritol, 60g N, N' -dimethylformamide, 90g of petroleum ether and 2mmol of p-toluenesulfonic acid into a 1L reaction vessel, and reacting for 48h at 90 ℃ under stirring.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing with the deionized water for three times, and drying to obtain an intermediate B, wherein the reaction yield in the first step is 95%. The nuclear magnetic resonance hydrogen spectrum of intermediate B having a cyclic acetal structure is shown in fig. 1.

S3, 0.1mol of intermediate B, 0.4mol of ethylene carbonate, 1mmol of anhydrous potassium carbonate and 90g of dimethyl sulfoxide are added to a reaction vessel and reacted at 180 ℃ for 8 h.

S4, precipitating and separating the reaction mixture in deionized water to obtain a solid product, washing the solid product with the deionized water for three times, and drying to obtain the rigid diol monomer with the structural formula shown in the formula V, wherein the reaction yield in the second step is 96%. The hydrogen nuclear magnetic resonance spectrum of the rigid diol monomer having a cyclic acetal structure obtained in this example is shown in FIG. 2.

Example 2

S1, 0.4mol of ethyl vanillin, 0.19mol of erythritol, 40g of dimethyl sulfoxide, 90g of ethyl acetate and 3mmol of p-toluenesulfonic acid are added into a 1L reaction vessel and reacted for 24 hours at 100 ℃ under stirring.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing with the deionized water for three times, and drying to obtain an intermediate B, wherein the reaction yield in the first step is 92%.

S3, 0.1mol of intermediate B, 0.5mol of ethylene carbonate, 0.1mmol of anhydrous potassium carbonate and 90g of dioxane are added to a reaction vessel and reacted at 200 ℃ for 24 h.

S4, precipitating and separating the reaction mixture in deionized water to obtain a solid product, washing the solid product with the deionized water for three times, and drying to obtain the rigid diol monomer with the structural formula shown in the formula VI, wherein the reaction yield of the second step is 95%.

Example 3

S1, 0.4mol of syringaldehyde, 0.18mol of erythritol, 60g N, N' -dimethylformamide, 90g of petroleum ether and 2mmol of p-toluenesulfonic acid are added into a 1L reaction vessel, and the mixture is reacted for 72 hours at 90 ℃ under stirring.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing the solid product with the deionized water for three times to obtain an intermediate B, wherein the reaction yield in the first step is 90%.

S3, 0.1mol of intermediate B, 0.8mol of ethylene carbonate, 1mmol of sodium carbonate and 70g N-methyl pyrrolidone are added into a reaction vessel and reacted at 250 ℃ for 0.5 h.

S4, precipitating and separating the reaction mixture in deionized water to obtain a solid product, washing the solid product with the deionized water for three times, and drying to obtain the rigid diol monomer with the structural formula shown in the formula VII, wherein the reaction yield of the second step is 86%.

Example 4

S1, 0.4mol of p-hydroxybenzaldehyde, 0.22mol of erythritol, 50g N, N' -dimethylformamide, 100g of petroleum ether and 3mmol of p-toluenesulfonic acid were added to a 1L reaction vessel, and the mixture was reacted at 95 ℃ for 30 hours with stirring.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing the solid product with the deionized water for three times to obtain an intermediate B, wherein the reaction yield in the first step is 90%.

S3, 0.1mol of intermediate B, 0.8mol of ethylene carbonate, 1mmol of sodium carbonate and 120g of diethyl ether are added to the reaction vessel and reacted at 60 ℃ for 72 h.

S4, precipitating and separating the reaction mixture in deionized water to obtain a solid product, washing the solid product with the deionized water for three times to obtain the rigid diol monomer with the structural formula shown in the formula IV, wherein the reaction yield in the second step is 96%.

Example 5

S1, adding 0.4mol of vanillin, 0.2mol of erythritol, 60g of dioxane, 100g of dichloromethane and 2mmol of p-toluenesulfonic acid into a 1L reaction vessel, and reacting at 150 ℃ for 5 h.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing the solid product with the deionized water for three times, and fully drying the solid product in a vacuum oven at 80 ℃ to obtain an intermediate B, wherein the reaction yield of the first step is 94%.

S3, 0.1mol of intermediate B, 0.5mol of ethylene carbonate, 0.5mmol of sodium carbonate and 90g of acetone are added to the reaction vessel and reacted at 80 ℃ for 72 h.

S4, precipitating and separating the reaction mixture in deionized water to obtain a solid product, washing the solid product with the deionized water for three times to obtain the rigid diol monomer with the structural formula shown in the formula V, wherein the reaction yield of the second step is 94%.

Example 6

S1, adding 0.4mol of vanillin, 0.2mol of erythritol, 30g N-methyl pyrrolidone, 100g of petroleum ether and 2mmol of p-toluenesulfonic acid into a 1L reaction vessel, and reacting at 130 ℃ for 8 h.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing the solid product with the deionized water for three times to obtain an intermediate B, wherein the reaction yield in the first step is 93%.

S3, 0.1mol of intermediate B, 0.4mol of ethylene carbonate, 1mmol of sodium bicarbonate and 90g of N-methylpyrrolidone are added to the reaction vessel and reacted at 170 ℃ for 12 h.

S4, precipitating and separating the reaction mixture in deionized water to obtain a solid product, washing the solid product with the deionized water for three times to obtain the rigid diol monomer with the structural formula shown in the formula V, wherein the reaction yield in the second step is 95%.

Example 7

S1, 0.4mol of ethyl vanillin, 0.22mol of erythritol, 60g N, N' -dimethylformamide, 100g of petroleum ether and 20mmol of p-toluenesulfonic acid are added into a 1L reaction vessel and reacted at 150 ℃ for 0.5 h.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing the solid product with the deionized water for three times to obtain an intermediate B, wherein the reaction yield in the first step is 94%.

S3, 0.1mol of intermediate B, 0.4mol of ethylene carbonate, 0.5mmol of anhydrous potassium carbonate and 90g N-methyl pyrrolidone are added into a reaction vessel and reacted at 190 ℃ for 8 h.

S4, precipitating and separating the reaction mixture in deionized water to obtain a solid product, washing the solid product with the deionized water for three times to obtain the rigid diol monomer with the structural formula shown in the formula VI, wherein the reaction yield in the second step is 94%.

Example 8

S1, adding 0.4mol of syringaldehyde, 0.2mol of erythritol, 60g of tetrahydrofuran, 90g of trichloromethane and 2mmol of p-toluenesulfonic acid into a 1L reaction vessel, and reacting at 90 ℃ for 48 hours.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing the solid product with the deionized water for three times to obtain an intermediate B, wherein the reaction yield in the first step is 90%.

S3, 0.1mol of intermediate B, 0.4mol of ethylene carbonate, 1mmol of anhydrous potassium carbonate and 90g of dimethyl sulfoxide are added to a reaction vessel and reacted at 180 ℃ for 8 h.

S4, precipitating and separating the reaction mixture in deionized water to obtain a solid product, washing the solid product with the deionized water for three times to obtain the rigid diol monomer with the structural formula shown in the formula VII, wherein the reaction yield in the second step is 92%.

Example 9

S1, 0.4mol of p-hydroxybenzaldehyde, 0.2mol of erythritol, 60g of diethyl ether, 90g of cyclohexane and 2mmol of p-toluenesulfonic acid are added into a 1L reaction vessel and reacted at 90 ℃ for 48 hours.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing the solid product with the deionized water for three times to obtain an intermediate B, wherein the reaction yield in the first step is 91%.

S3, 0.1mol of intermediate B, 0.6mol of ethylene carbonate, 0.1mmol of sodium bicarbonate and 90g of butanone are added to the reaction vessel and reacted at 250 ℃ for 4 h.

S4, precipitating and separating the reaction mixture in deionized water to obtain a solid product, washing the solid product with the deionized water for three times to obtain the rigid diol monomer with the structural formula shown in the formula IV, wherein the reaction yield in the second step is 85%.

Example 10

S1, 0.4mol of p-hydroxybenzaldehyde, 0.18mol of erythritol, 50g of acetone, 100g of methanol and 20mmol of p-toluenesulfonic acid were added to a 1L reaction vessel, and reacted at 20 ℃ for 72 hours.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing the solid product with the deionized water for three times to obtain an intermediate B, wherein the reaction yield in the first step is 95%.

S3, 0.1mol of intermediate B, 0.7mol of ethylene carbonate, 0.5mmol of anhydrous potassium carbonate and 90g of dimethyl sulfoxide are added to a reaction vessel, and the mixture is reacted at 220 ℃ for 18 hours.

S4, precipitating and separating the reaction mixture in deionized water to obtain a solid product, washing the solid product with the deionized water for three times to obtain the rigid diol monomer with the structural formula shown in the formula IV, wherein the reaction yield in the second step is 93%.

Example 11

S1, 0.4mol of ethyl vanillin, 0.2mol of erythritol, 60g of dioxane, 100g of ethanol and 10mmol of ferric chloride are added into a 1L reaction vessel and reacted for 72 hours at 70 ℃.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing the solid product with the deionized water for three times to obtain an intermediate B, wherein the reaction yield in the first step is 89%.

S3, 0.1mol of intermediate B, 0.4mol of ethylene carbonate, 1mmol of anhydrous potassium carbonate and 90g of N, N' -dimethylformamide are added to the reaction vessel and reacted at 230 ℃ for 0.5 h.

S4, precipitating and separating the reaction mixture in deionized water to obtain a solid product, washing the solid product with the deionized water for three times to obtain the rigid diol monomer with the structural formula shown in the formula VI, wherein the reaction yield in the second step is 92%.

Example 12

S1, 0.4mol of syringaldehyde, 0.2mol of erythritol, 40g of butanone, 90g of petroleum ether and 3mmol of indium fluoride are added into a 1L reaction vessel and reacted at 90 ℃ for 48 hours.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing the solid product with the deionized water for three times to obtain an intermediate B, wherein the reaction yield in the first step is 92%.

S3, 0.1mol of intermediate B, 0.4mol of ethylene carbonate, 1mmol of sodium carbonate and 90g of tetrahydrofuran are added to the reaction vessel and reacted at 180 ℃ for 8 h.

S4, precipitating and separating the reaction mixture in deionized water to obtain a solid product, washing the solid product with the deionized water for three times to obtain the rigid diol monomer with the structural formula shown in the formula VII, wherein the reaction yield in the second step is 91%.

Comparative example 1

S1, adding 0.4mol of vanillin, 0.2mol of erythritol, 60g N, N' -dimethylformamide, 90g of petroleum ether and 2mmol of p-toluenesulfonic acid into a 1L reaction vessel, and reacting at 15 ℃ for 72 h.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing the solid product with the deionized water for three times to obtain an intermediate B, wherein the reaction yield in the first step is 32%.

S3, 0.1mol of intermediate B, 0.4mol of ethylene carbonate, 1mmol of anhydrous potassium carbonate and 90g of dimethyl sulfoxide are added to a reaction vessel and reacted at 140 ℃ for 12 hours.

S4, precipitating and separating the reaction mixture in deionized water to obtain a solid product, washing the solid product with the deionized water for three times to obtain the rigid diol monomer with the structural formula shown in the formula V, wherein the yield of the second step is 75%, and the total yield of the two steps is only 24%.

As can be seen from the comparative analysis of comparative example 1 and examples 1 to 12, the reaction temperature used in comparative example 1 is relatively low, and the target product can be obtained even if the reaction time is prolonged, but the reaction yield is very low, and the practical value is not high. Therefore, it is necessary to obtain a more desirable yield, and the reaction temperature is set within a suitable range.

Comparative example 2

S1, adding 0.4mol of vanillin, 0.2mol of erythritol, 40g of dimethyl sulfoxide and 3mmol of p-toluenesulfonic acid into a 1L reaction vessel, and reacting at 90 ℃ for 48 hours.

S2, precipitating and separating the reaction mixture in deionized water, performing suction filtration to obtain a solid product, washing the solid product with the deionized water for three times to obtain an intermediate B, wherein the reaction yield in the first step is 13%.

As is clear from the comparative analysis between comparative example 2 and examples 1 to 12, in comparative example 2, no organic solvent for carrying water was added in step S1, so that the reaction equilibrium was hardly shifted toward the formation of intermediate B, and the yield in the first step was low, and thus it was not practical. Therefore, it is necessary to obtain a desired reaction yield, and a suitable organic solvent must be added in step S1.

In addition, the inventors of the present invention have also made experiments with other materials, process operations, and process conditions described in the present specification with reference to the above examples, and have obtained preferable results.

While the invention has been described with reference to illustrative embodiments, it will be understood by those skilled in the art that various other changes, omissions and/or additions may be made and substantial equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated any use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.