阅读说明：本技术 一种活性蔗渣木聚糖对溴苯甲酸/桂皮酸双酯的合成方法 (Method for synthesizing active bagasse xylan p-bromobenzoic acid/cinnamic acid diester ) 是由 李和平 李明坤 葛文旭 杨锦武 郑光绿 柴建啟 武晋雄 耿恺 杨莹莹 于 2019-10-22 设计创作，主要内容包括：本发明公开了一种活性蔗渣木聚糖对溴苯甲酸/桂皮酸双酯的合成方法。以天然高分子蔗渣木聚糖为主要原料,首先以对甲苯磺酸为催化剂,DMF为反应溶剂,对溴苯甲酸为酯化剂,通过酯化反应合成蔗渣木聚糖对溴苯甲酸酯；然后以桂皮酰氯为酯化剂,二氯甲烷为反应溶剂,<I>N</I>,<I>N’</I>-二异丙基碳二亚胺与三乙胺为复合催化剂,将蔗渣木聚糖对溴苯甲酸酯与桂皮酰氯进行第二步酯化反应,合成蔗渣木聚糖对溴苯甲酸/桂皮酸双酯衍生物。采用双步酯化反应合成的目标产物蔗渣木聚糖对溴苯甲酸/桂皮酸双酯,不仅提高了蔗渣木聚糖的水溶性,同时引入桂皮酸和对溴苯甲酸的活性基团提高了蔗渣木聚糖的抗HIV等活性。(The invention discloses a method for synthesizing active bagasse xylan p-bromobenzoic acid/cinnamic acid diester. Taking natural high molecular bagasse xylan as a main raw material, firstly, taking p-toluenesulfonic acid as a catalyst, DMF as a reaction solvent and p-bromobenzoic acid as an esterifying agent, and synthesizing bagasse xylan-p-bromobenzoate through an esterification reaction; then using cinnamoyl chloride as an esterifying agent and dichloromethane as a reaction solvent, N , N' and (3) taking diisopropyl carbodiimide and triethylamine as composite catalysts, and carrying out a second esterification reaction on bagasse xylan p-bromobenzoate and cinnamoyl chloride to synthesize the bagasse xylan p-bromobenzoate/cinnamic acid diester derivative. The bagasse xylan diester with bromobenzoic acid/cinnamic acid as the target product synthesized by adopting the two-step esterification reaction not only improves the water solubility of the bagasse xylan, but also improves the activities of resisting HIV and the like of the bagasse xylan by introducing the active groups of cinnamic acid and bromobenzoic acid.)

1. A method for synthesizing active bagasse xylan p-bromobenzoic acid/cinnamic acid diester is characterized by comprising the following specific steps:

(1) drying 7-10 g of bagasse xylan in a vacuum constant-temperature drying oven at 60 ℃ for 24 hours to constant weight to obtain dry-based bagasse xylan;

(2) weighing 3-6 g of the dry bagasse xylan obtained in the step (1), adding the dry bagasse xylan into a 250mL four-neck flask, adding 30-50 mL of analytically pure N, N-dimethylformamide, and stirring at room temperature for 20-30 minutes;

(3) heating the material in the step (2) to 40-50 ℃, and adding 0.2-0.3 g of p-toluenesulfonic acid; weighing 15-20 mL of analytically pure p-bromobenzoic acid, adding the analytically pure p-bromobenzoic acid into a 50mL constant-pressure dropping funnel, beginning to drop into the system, and controlling the dropping time to be 40-60 minutes after the dropping is finished; after the dropwise addition is finished, continuously reacting for 2-3 hours; after the reaction is finished, cooling the system to room temperature;

(4) adding 20-30 mL of analytically pure acetone into the material obtained in the step (3), uniformly stirring, precipitating for 20-30 minutes, filtering, washing with 10-20 mL of analytically pure absolute ethanol, performing suction filtration for 2-3 times, putting a filter cake into a watch glass, and drying in a vacuum constant-temperature drying oven at 50 ℃ for 24 hours to constant weight to obtain bagasse xylan p-bromobenzoate;

(5) weighing 4-5 g of the bagasse xylan p-bromobenzoate obtained in the step (4), adding the bagasse xylan p-bromobenzoate into a 250mL four-neck flask, adding 15-20 mL of analytically pure dichloromethane solution, and stirring for 10-15 minutes to obtain a suspension solution system;

(6) weighing 3-5 g of cinnamic acid acyl chloride, adding into the system obtained in the step (5), and simultaneously adding 0.1-0.2 g N, N'Diisopropyl carbodiimide and 0.1-0.3 mL of analytically pure triethylamine, controlling the reaction temperature at 60-70 ℃ to continuously react for 3-4 hours, cooling the system to room temperature, and filtering to obtain bagasse xylanCrude product of p-bromobenzoic acid/cinnamic acid diester;

(7) transferring the crude product obtained in the step (6) to a 200mL beaker, adding 30-50 mL of analytically pure absolute ethyl alcohol, uniformly stirring at room temperature, and standing for 1-2 hours to obtain a white precipitate; washing with 100-150 mL of distilled water, carrying out suction filtration for 3-5 times, and drying a filter cake in a vacuum drying oven at 60 ℃ to constant weight to obtain a pure bagasse xylan p-bromobenzoic acid/cinnamic acid diester product.

Technical Field

The invention relates to the field of fine chemical engineering and biomass materials, in particular to a method for synthesizing bagasse xylan-p-bromobenzoic acid/cinnamic acid diester.

Background

The xylan is taken as a polysaccharide widely existing in the nature, has certain anticancer activity, and meanwhile, a large number of hydroxyl groups with high activity exist on the molecular chain of the xylan, so that good conditions are created for chemical modification of the xylan. However, a large number of intramolecular and intermolecular hydrogen bonds are formed among hydroxyl groups, so that high-activity hydroxyl groups of xylan are enclosed in a crystal region, xylan is optimized in a chemical modification mode, the hydrogen bond function is removed, and the active hydroxyl groups of xylan can be effectively activated.

Esterification is an effective method for improving biological activity of xylan, for example, sulfated derivatives of xylan increase anti-tumor and anti-HIV activity while enhancing the anti-viral activity. The esterification of xylan and aromatic acid with certain activity can effectively enhance the biological activity of xylan macromolecules. The p-bromobenzoic acid and the bagasse xylan are subjected to esterification reaction, so that the hydrogen bond effect of the xylan can be partially removed, active hydroxyl groups in a xylan crystal region are excited, and the biological activity of the xylan and derivatives thereof is improved. After improving the hydrogen bond effect in xylan molecules, cinnamic acid with bioactivity is used as a second active organic acid to carry out secondary esterification with xylan monoesterification, so that the bioactivity of bagasse xylan is further improved.

The method takes natural high molecular bagasse xylan as a main raw material, firstly takes p-toluenesulfonic acid as a catalyst, DMF as a reaction solvent and p-bromobenzoic acid as an esterifying agent, and synthesizes bagasse xylan-p-bromobenzoate through esterification reaction; then, taking cinnamoyl chloride as an esterifying agent, dichloromethane as a reaction solvent, and N, N' -diisopropyl carbodiimide (DIC) and triethylamine as a composite catalyst, and carrying out a second esterification reaction on bagasse xylan p-bromobenzoate and cinnamoyl chloride to synthesize the bagasse xylan p-bromobenzoate/cinnamic acid diester derivative.

Disclosure of Invention

The invention aims to improve the intramolecular hydrogen bond effect of bagasse xylan, enhance the bioactivity of the bagasse xylan, and provide a method for synthesizing bromobenzoic acid/cinnamic acid diester by using active bagasse xylan.

The method comprises the following specific steps:

(1) and (3) drying 7-10 g of bagasse xylan in a vacuum constant-temperature drying oven at 60 ℃ for 24 hours to constant weight to obtain the dry-based bagasse xylan.

(2) Weighing 3-6 g of the dry bagasse xylan obtained in the step (1), adding the dry bagasse xylan into a 250mL four-neck flask, and adding 30-50 mL of analytically pure N, N-dimethylformamide ₍DMF) at room temperature for 20-30 minutes.

(3) Heating the material in the step (2) to 40-50 ℃, and adding 0.2-0.3 g of p-toluenesulfonic acid. Weighing 15-20 mL of analytically pure p-bromobenzoic acid, adding the analytically pure p-bromobenzoic acid into a 50mL constant-pressure dropping funnel, beginning to drop into the system, and controlling the dropping time to be 40-60 minutes after the dropping is finished; and continuing to react for 2-3 hours after the dropwise addition is finished. After the reaction is finished, the system is cooled to room temperature.

(4) And (3) adding 20-30 mL of analytically pure acetone into the material obtained in the step (3), precipitating for 20-30 minutes after uniformly stirring, filtering, washing with 10-20 mL of analytically pure absolute ethyl alcohol, performing suction filtration for 2-3 times, putting a filter cake into a watch glass, and drying in a vacuum constant-temperature drying oven at 50 ℃ for 24 hours to constant weight to obtain the bagasse xylan-p-bromobenzoate.

(5) And (3) weighing 4-5 g of the bagasse xylan p-bromobenzoate obtained in the step (4), adding into a 250mL four-neck flask, adding 15-20 mL of analytically pure dichloromethane solution, and stirring for 10-15 minutes to obtain a suspension solution system.

(6) And (3) weighing 3-5 g of cinnamic acid acyl chloride, adding into the system obtained in the step (5), simultaneously adding 0.1-0.2 g of N, N' -diisopropylcarbodiimide and 0.1-0.3 mL of analytically pure triethylamine, controlling the reaction temperature at 60-70 ℃ to continuously react for 3-4 hours, cooling the system to room temperature, and filtering to obtain a crude product of bagasse xylan p-bromobenzoic acid/cinnamic acid diester.

(7) Transferring the crude product obtained in the step (6) to a 200mL beaker, adding 30-50 mL of analytically pure absolute ethyl alcohol, uniformly stirring at room temperature, and standing for 1-2 hours to obtain a white precipitate; washing with 100-150 mL of distilled water, carrying out suction filtration for 3-5 times, and drying a filter cake in a vacuum drying oven at 60 ℃ to constant weight to obtain a pure bagasse xylan p-bromobenzoic acid/cinnamic acid diester product.

(8) And (3) determining the substitution degree of bromobenzoyl in the bagasse xylan double-esterification product by adopting an acid-base titration method. The method comprises the following specific steps: about 1.0g of the sample was accurately weighed into a 250mL Erlenmeyer flask, 10mL of deionized water was added, 4 drops of phenolphthalein indicator were added dropwise, and the solution was titrated to reddish color with 0.1mol/L NaOH. Then, 5.0mL of a 0.5mol/L NaOH standard solution was added thereto, and the mixture was shaken up. Shaking for 60 minutes at room temperature, washing the stopper and the bottle wall of the conical flask with a small amount of distilled water, finally titrating with 0.5mol/L hydrochloric acid standard solution until the red color just disappears as the end point, and recording the consumption volume V of the hydrochloric acid standard solution ₁. Under the same conditions, blank titration is carried out by using bagasse xylan, and the volume V of the consumed hydrochloric acid standard solution is recorded ₀. The calculation formula is as follows:

in the formula:

W _c-mass fraction of p-bromobenzoyl in the target product,%;

V ₀titrating the volume of the hydrochloric acid standard solution consumed by the bagasse xylan in unit mL;

V ₁titration of the volume of standard solution of hydrochloric acid consumed by the final product, in mL;

C _HCl-the concentration of the hydrochloric acid standard solution in mol/L;

m is the mass of the target product sample in g;

m-relative molecular mass of p-bromobenzoyl;

132-relative molecular mass of bagasse xylan dewatering units;

DS — degree of substitution of bromobenzoyl by bagasse xylan.

The bagasse xylan diester with bromobenzoic acid/cinnamic acid as the target product synthesized by adopting the two-step esterification reaction not only improves the water solubility of the bagasse xylan, but also improves the activities of resisting HIV and the like of the bagasse xylan by introducing the active groups of cinnamic acid and bromobenzoic acid.

Drawings

FIG. 1 is an IR chart of bagasse xylan.

FIG. 2 is an IR chart of bagasse xylan against bromobenzoic acid/cinnamic acid diester.

Fig. 3 is an SEM photograph of bagasse xylan.

FIG. 4 is an SEM photograph of bagasse xylan versus bromobenzoic acid/cinnamic acid diester.

Figure 5 is an XRD pattern of bagasse xylan.

FIG. 6 is an XRD pattern of bagasse xylan versus bromobenzoic acid/cinnamic acid diester.

FIG. 7 is a TG-DTG curve of bagasse xylan.

FIG. 8 is a TG-DTG curve of bagasse xylan vs. bromobenzoic acid/cinnamic acid diester.

Detailed Description