Benzofuranone chitosan composite, preparation method thereof and application thereof in the field of historical block renewal

Abstract

The present invention discloses a benzofuranone chitosan composite, a preparation method thereof and an application thereof in the field of historical block renewal. Experimental results show that the benzofuranone chitosan composite of the present invention can significantly inhibit the growth of brown rot fungi, white rot fungi and soft rot fungi, solves the shortcomings of the existing antibacterial agents of high toxicity and poor durability, has the characteristics of stronger antibacterial activity, longer antibacterial time and lower toxicity, and has good promotion and application value in the fields of historical block protection and old building renovation.

Description

Technical Field

[0001] The invention relates to the field of antibacterial agent production, and specifically provides a benzofuranone chitosan complex, a preparation method thereof and application thereof in the field of historical block renewal. Background Art

[0002] Wood is the most important building material in historical buildings and old houses. Many historical blocks are also seriously affected by the decay or mildew of wood in historical buildings and old houses. In today's society, the issue of housing for the elderly, the protection of historical buildings and tourism development have become hot topics of social concern. Among them, the safety of houses that use wooden building materials for more than 30 years is particularly serious, which brings huge problems to urban and rural planning and construction, as well as the commercial development of historical and cultural blocks. The use of green and pollution-free wood preservatives is currently the most effective means of old city renewal, historical buildings and old housing renovation. The development of new wood preservatives is also one of the important research directions in the field of construction engineering.

[0003] Traditional wood preservatives are mainly oil preservatives and organic solvent preservatives, but due to their high toxicity to humans and animals and serious pollution to the environment, most varieties have been restricted for use, and cannot be used in residential housing, tourist attractions, and are even gradually eliminated in the market. The newly developed Chinese medicine or biomass wood preservatives are expensive, have a narrow antibacterial spectrum, are not water-soluble, have poor durability and resistance to loss, and are difficult to promote. Some Chinese medicine preservatives become moldy in less than a year, and some liquid preservatives react chemically with the paint on the surface of cultural relics, causing discoloration or corrosion, which is not suitable for the needs of historical building anticorrosion. In this field, it is of great significance to develop new special preservatives that are friendly to the human body and have long-term antibacterial properties for historical buildings and old houses in use. Summary of the invention

[0004] The present invention aims at the deficiencies of the above-mentioned prior art and provides a benzofuranone chitosan composite having the characteristics of broad-spectrum safety, high-efficiency antibacterial, non-toxicity, and degradability.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] The benzofuranone chitosan complex represented by formula (II) is

[0007] .

[0008] The present invention provides a method for preparing a benzofuranone chitosan complex represented by structural formula (II), comprising the following steps:

[0009] S1. preparing a compound represented by structural formula (III) using a benzofuranone derivative represented by structural formula (I) and oxalyl chloride as raw materials;

[0010] S2. using the compound represented by structural formula (III) and chitosan as raw materials to prepare a benzofuranone chitosan complex represented by structural formula (II),

[0011] The reaction equation is as follows:

[0012]

[0013] Preferably, the preparation method of the benzofuranone derivative represented by structural formula (I) comprises:

[0014] A1. Tetrabutylammonium bromide, p-methoxybenzaldehyde and chloroform are mixed, heated and stirred after dissolving, and 50% NaOH solution is added dropwise. After the reaction is complete, it is filtered and recrystallized to obtain p-methoxymandelic acid. The usage ratio of tetrabutylammonium bromide, p-methoxybenzaldehyde, chloroform and 50% NaOH solution is 1 mol: 15-40 mol: 20-50 mol: 1-3 L.

[0015] A2. p-Methoxymandelic acid, 3-methoxycatechol and boron trifluoride etherate are mixed and stirred. After the reaction is completed, the reaction solution is poured into ice water and stirred sufficiently. The precipitate is filtered and dried to obtain a benzofuranone derivative represented by structural formula (I). The amount ratio of p-Methoxymandelic acid, 3-methoxycatechol and boron trifluoride etherate is 20 mol: 20-40 mol: 20-40 L.

[0016] The reaction equation is as follows:

[0017]

[0018] Preferably, step S1 comprises: reacting the benzofuranone derivative represented by structural formula (I) with oxalyl chloride in acetone, and purifying the reaction product to obtain a compound represented by structural formula (III).

[0019] Preferably, the reaction of the benzofuranone derivative represented by the structural formula (I) with oxalyl chloride in acetone comprises adding the benzofuranone derivative represented by the structural formula (I) to acetone, and then adding oxalyl chloride to react in an ice-water bath under nitrogen protection.

[0020] Preferably, the molar ratio of oxalyl chloride to the benzofuranone derivative represented by the structural formula (I) is 1:(1-3), particularly preferably 1:(1.5-2).

[0021] Preferably, in the acetone solution of the benzofuranone derivative represented by the structural formula (I), the mass fraction of the benzofuranone derivative represented by the structural formula (I) is 2 to 8%.

[0022] Preferably, the purification process of the reaction product in step S1 comprises: adding the product to dry triethylamine, stirring to remove excess oxalyl chloride and generated hydrogen chloride, filtering to remove by-products generated by the reaction of triethylamine and oxalyl chloride, then distilling under reduced pressure to remove the solvent, adding NaOH solution to filter, washing the filter cake with distilled water and a small amount of ethanol until the pH value is 7.4, and then recrystallizing with acetone to obtain a compound represented by structural formula (III).

[0023] Preferably, step S2 comprises: adding chitosan to an acetone solution of the compound represented by structural formula (III) and stirring, and removing the solvent after the reaction to obtain a benzofuranone chitosan complex represented by structural formula (II).

[0024] Preferably, the step of adding chitosan to an acetone solution of the compound represented by formula (III) and stirring comprises: dissolving the compound represented by formula (III) in acetone, then adding a certain amount of chitosan powder, and stirring under nitrogen protection and an ice-water bath.

[0025] Preferably, the ratio of chitosan to 7-hydroxy-6-methoxy-3-(4'-methoxy)benzofuranone (benzofuranone derivative represented by structural formula (I)) is 1 g:(0.01-0.5) g, particularly preferably 1 g:(0.05-0.2) g.

[0026] Preferably, in the acetone solution of the compound represented by structural formula (III), the mass fraction of the compound represented by structural formula (III) is 3 to 10%.

[0027] Preferably, the molecular weight of the chitosan is 30,000 to 80,000, and the chitosan is added to the acetone solution of the compound represented by the structural formula (III) at a concentration of 0.2 to 2 g / L.

[0028] The present invention provides application of a benzofuranone chitosan complex represented by structural formula (II) in building anticorrosion, historical building protection, and old housing reconstruction.

[0029] Preferably, the benzofuranone chitosan complex represented by structural formula (II) is mainly used to treat wood or wood composite materials in buildings to inhibit the growth of fungi that cause wood decay. The wood includes fir, pine, chestnut, beech, cypress, camphor, nanmu, etc. The fungi include white rot fungi, brown rot fungi, discoloration fungi or soft rot fungi, etc.

[0030] Preferably, the benzofuranone chitosan complex represented by the structural formula (II) can be used to treat the surface of building wood by dipping, painting, spraying and other methods known in the art. When dipping, the wood can be immersed in an aqueous solution of the complex at a concentration of 10 to 100 g / L (preferably 40 to 60 g / L) for 1 to 72 hours (preferably 10 to 36 hours); when painting or spraying, 0.02 to 0.3 kg of the complex can be applied per square meter of the wood surface.

[0031] Treatments such as dipping, painting, and spraying can be performed at 0 to 80°C and 50 to 115 kPa, preferably 10 to 30°C and 85 to 105 kPa.

[0032] The invention provides a building material antibacterial agent composition, which contains a benzofuranone chitosan complex represented by structural formula (II).

[0033] The antibacterial composition may contain other active ingredients or adjuvants known in the art that do not affect its activity, such as other bactericides, solutions, adhesives, co-solvents, etc.

[0034] Compared with the prior art, the composite material of the present invention, its preparation method and its application in the field of historical building protection have the following outstanding beneficial effects:

[0035] (I) Benzofuranone and chitosan produce synergistic and synergistic effects, which enhance the broad-spectrum and antibacterial ability of preservatives. It can effectively resist a variety of molds including white rot fungi, brown rot fungi, discoloration fungi, soft rot fungi, etc. It is particularly suitable for the mildew of historical buildings and old houses, and prolongs the life of buildings;

[0036] (ii) The chitosan in the present invention is a pure natural product, and benzofuranone is a derivative of a natural product. The composite as a whole has been verified to be non-toxic by experiments, and can be used in housing for a long time in large doses, and is particularly suitable for the anti-corrosion of wooden buildings used in human habitation and tourism development;

[0037] (III) The present invention has good adhesion to common woods such as fir, pine, chestnut, beech, cypress, camphor, and nanmu in historical buildings, has anti-loss properties, and has a long anti-corrosion time. Under laboratory conditions, 10g of the compound has a longer anti-corrosion time per square meter of wood than existing water-soluble preservatives, and has low cost, making it particularly suitable for the long-term protection of old urban buildings;

[0038] (IV) Historical buildings, especially wood with paint or other dyes attached to it, are very likely to fade when treated with chemical solvents, causing damage to cultural relics. This preservative has stable chemical properties, is water-soluble, and can avoid the use of organic solvents. It is not easy to cause damage to historical buildings, especially for the paint of historical buildings. There is no obvious chemical reaction, no corrosion or dissolution signs, which helps to maintain the original appearance of historical buildings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Attached Figure 1 It is the growth curve of white rot fungi in Example 6. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0041] Example 1

[0042] Synthesis of 7-Hydroxy-6-methoxy-3-(4'-methoxy)benzofuranone

[0043] Add 40mmol of p-methoxybenzaldehyde, 2mmol of tetrabutylammonium bromide and 50mL of chloroform to a 500ml three-necked flask equipped with a dropping funnel and a reflux condenser. After the raw materials are completely dissolved, stir at 45°C for 4 hours. Slowly add 5ml of 50% NaOH solution and maintain for about 2 hours. After the reaction is complete, let it stand and cool, and extract the solid precipitate. Wash the filter cake with chloroform 3 times to obtain a white solid mixture of sodium mandelate and sodium chloride. Add the solid mixture to a flask with dilute hydrochloric acid for acidification, let it stand for a period of time, extract it with ethyl acetate three times, and combine the organic phases to dry and concentrate with anhydrous Na2SO4. Recrystallize from acetone / petroleum ether to obtain a white solid as substituted mandelic acid with a yield of 81%.

[0044] Add 20mmol of p-methoxymandelic acid, 25mmol of 3-methoxycatechol and 25mL of boron trifluoride etherate to a 250ml three-necked flask equipped with a reflux condenser and a drying tube, and keep stirring at 40°C to completely dissolve the raw materials. Monitor the reaction after 6 hours. After the reaction is completed by TLC detection, let it stand and cool. Then pour the reaction solution into ice water and stir it thoroughly, and a large amount of solid precipitates will precipitate. The solid precipitate is filtered out, and the filter cake is repeatedly washed with a saturated NaHCO3 solution and distilled water. After drying, the compound of formula (I) is obtained with a yield of 95%, and the hydrogen spectrum, carbon spectrum and mass spectrum of the compound are determined.

[0045] .

[0046] White solid, 1 H NMR (600 MHz, DMSO-d6) δ 9.34 (s, 1H), 7.08 (d, J = 8.3Hz, 2H), 6.83 (d, J = 8.2 Hz, 2H), 6.71 (d, J = 7.9 Hz, 1H), 6.51 (d, J =7.8Hz, 1H), 5.11 (s, 1H), 3.71 (s, 3H), 3.68 (s, 3H).

[0047] 13 C NMR (151 MHz, DMSO-d6) δ 175.05, 158.01, 148.09, 140.51, 130.23,128.77, 127.65, 120.28, 114.01, 107.67, 55.55, 54.23, 48.01.

[0048] MS: m / z (%) [M+H] + : 286.0836, [M+Na] + : 309.0246.

[0049] Example 2

[0050] Synthesis of 7-Hydroxy-6-methoxy-3-(4'-methoxy)benzofuranone-chitosan composite

[0051] At room temperature, 5 g of 7-hydroxy-6-methoxy-3-(4'-methoxy)benzofuranone was added to 100 ml of acetone to dissolve. 6 g of oxalyl chloride was added to the mixture in a 0°C ice-water bath under nitrogen protection for homogeneous reaction. After 3 h of reaction, the product was added to 6 g of dry triethylamine in three portions and stirred for 4 h. Excess oxalyl chloride and generated hydrogen chloride were removed. The by-products generated by the reaction of triethylamine and oxalyl chloride were filtered out. Then, the solvent was removed by vacuum distillation. 1% NaOH solution was added to the mixture for filtration. The filter cake was washed with distilled water and a small amount of ethanol until the pH value was 7.4, and then recrystallized with acetone to obtain the intermediate 7-methyl ester chloride-6-methoxy-3-(4'-methoxy)benzofuranone.

[0052] 1 g of the prepared intermediate was dissolved in acetone to prepare a 5% acetone solution, and then chitosan powder (molecular weight of chitosan 30k-80k) was added according to the actual volume at a concentration of 1 g / L. The reaction was carried out under nitrogen protection and an ice-water bath at 0°C. After stirring the reaction for 8 hours, the acetone solvent was evaporated at 45°C to obtain a 7-hydroxy-6-methoxy-3-(4'-methoxy)benzofuranone-chitosan complex shown in the structural formula (II).

[0053] .

[0054] The product was analyzed by infrared spectrometer, and the product had a wavelength of 3170 cm -1 The characteristic absorption peak of -OH group disappears and the peak at 1710 cm -1 The characteristic absorption peak of carbonyl appears at 1790 cm -1 The characteristic peak of acyl chloride group appeared at , proving that the acylation reaction was successful.

[0055] Experimental example:

[0056] 1. Antimicrobial Testing

[0057] Take six representative fungi: two brown rot fungi: Gloeophyllum trabeum Glehnia littoralis and Rhodonia cake Two species of white rot fungi: Trametes versicolor Trametes versicolor and Milkweed White capsule rake tooth fungus. Two types of bacteria: Gram-positive bacteria Staphylococcus aureus Staphylococcus aureus and Gram-negative bacteria Escherichia coli Escherichia coli; the 7-hydroxy-6-methoxy-3-(4'-methoxy)benzofuranone-chitosan complex obtained in Example 2 was used as the sample to be tested.

[0058] Use an inoculation loop to pick up an appropriate amount of strains in a test tube containing liquid culture medium, shake the test tube gently, cover the test tube with a stopper, and place the test tube in a constant temperature incubator for incubation, keep the temperature at about 37°C, and control the speed at 100rmp. The above operation process is completed on a sterile operating table. After observing bacterial growth in the culture medium in the test tube, transfer the bacteria to a culture dish and place it in an incubator for continued incubation. The sample to be tested is prepared into a solution with a concentration of 100μg / mL with water. 1.0mg / mL double antibody (half penicillin and half streptomycin as double antibody) is used as a positive control. The compound is diluted by the two-fold method. Take a series of 15mL glass test tubes and number them from high concentration to low concentration. Set 10 concentrations of the complex, and add 0.8mL of the compound to be tested and 3.2mL of liquid culture medium in turn. Place the glass test tube in a constant temperature incubator for incubation, keep the temperature at about 37°C, and control the speed at 100rmp. The minimum inhibitory concentration is the average of the concentrations of samples with bacterial growth and without bacterial growth. The measurement results are shown in Table 1.

[0059] Table 1:

[0060]

[0061] *Dual resistance has obvious effects on various strains

[0062] It can be seen from the data in Table 1 that the composite has a good antibacterial effect.

[0063] 2. Toxicity Testing

[0064] KM mice were selected for the experiment (the mice were purchased from Jinan Pengyue Experimental Animal Breeding Co., Ltd., and the company license number is SCXK (Lu) 20190003). Mice were raised in a constant temperature animal room and fasted but not watered for 12 hours before the experiment. The complex obtained in Example 2 was prepared with distilled water at a concentration of 0.2 mL / 10 g and administered by gavage. The experiment was divided into two dose groups of 1000 mg / kg and 5000 mg / kg, with 10 mice in each group. The mice were gavaged once, and the death of the mice and the changes in general signs were observed after 24 hours. The observation was continued for 14 days, and the changes in the behavioral patterns of the mice after gavage were recorded (see Table 2 for details). The mice were killed after the experiment.

[0065] Table 2:

[0066]

[0067] From the results in Table 2, it can be seen that the complex has no obvious toxicity to mice.

[0068] 3. Wood antibacterial testing

[0069] The compound obtained in Example 2 was dissolved in water and a 20 g / L solution was prepared with the same solvent. An oven-dried branch of fir, pine or chestnut (cut to a size of about 75x20x4 mm) was immersed in 25 ml of the solution until it was thoroughly soaked. After 5 hours, the test solution was poured out and each branch was dried under sterile laminar airflow. In each culture dish, a branch was placed on malt agar pre-inoculated with fungi. The culture dishes were then kept warm at 20°C and 90°C relative humidity. After the fungi on the untreated control branches were fully grown, the treated branches were evaluated (see Table 3 for details).

[0070] Table 3:

[0071]

[0072] (+++ More than 80% of the area is covered by colonies, ++ More than 10% of the area is covered by colonies, + Less than 10% of the area is covered by colonies, - No coverage at all)

[0073] It can be seen from Table 3 that the composite has a good antifungal effect on wood.

[0074] IV. Effect of the composite obtained in Example 2 on the growth curve of white rot fungus (Irpex lacteus)

[0075] The same volume of white rot fungus supernatant was inoculated into the same volume of blank culture medium and complex culture medium for cultivation, and the OD value in the culture medium was measured at the same time every day from day 0 to day 7. The growth curve of white rot fungi under different growth conditions was drawn with absorbance (OD value) as the ordinate and culture time as the abscissa (see Figure 1 ).

[0076] Depend on Figure 1 It can be seen that the complex significantly inhibited the growth of White Capsule Rake Tooth Fungus.

[0077] 5. Corrosion resistance test

[0078] Prepare corn sawdust culture medium. Use a hole puncher to punch the activated strains, and take a 5mm diameter bacterial block to inoculate in the middle part of the river sand sawdust culture medium. Place the inoculated culture bottle in a constant temperature and humidity incubator, and culture it for about 10 days at a temperature of 28°C and a humidity of 80%. When the bottle is full of mycelium, you can put in the pine wood block, fir wood block, and chestnut wood block soaked in the composite obtained in Example 2 (the concentration of the composite aqueous solution is 20g / L, and the soaking time is 1 day). After 12 weeks, the sample is taken out, the surface mycelium and impurities are gently scraped off, the specimen is dried in an oven at 105°C to constant weight, and each specimen is weighed separately to calculate the mass loss rate. The results of the indoor corrosion resistance test are detailed in Table 4.

[0079] The calculation formula is shown in the formula: L= ×100%

[0080] Where:

[0081] M before - the absolute dry mass of the sample before the test, in grams (g)

[0082] Mafter - the absolute dry mass of the sample after the test, in grams (g)

[0083] Table 4:

[0084]

[0085] It can be seen from the data in Table 4 that the composite material can make wood more corrosion-resistant.

Claims

1. A benzofuranone chitosan complex represented by structural formula (II), 2. The method for preparing the benzofuranone chitosan complex of structural formula (II) as claimed in claim 1, characterized in that: The following steps are involved: S1. preparing a compound represented by structural formula (III) using a benzofuranone derivative represented by structural formula (I) and oxalyl chloride as raw materials; S2. using the compound represented by structural formula (III) and chitosan as raw materials to prepare a benzofuranone chitosan complex represented by structural formula (II), 3. The method for preparing the benzofuranone chitosan composite according to claim 2, characterized in that: Step S1 comprises: reacting the benzofuranone derivative represented by the structural formula (I) with oxalyl chloride in acetone, and purifying the reaction product to obtain the compound represented by the structural formula (III).

4. The method for preparing the benzofuranone chitosan composite according to claim 3, characterized in that: The molar ratio of oxalyl chloride to the benzofuranone derivative represented by the structural formula (I) is 1:(1-3).

5. The method for preparing the benzofuranone chitosan composite according to claim 2, characterized in that: Step S2 comprises: adding chitosan to an acetone solution of the compound represented by the structural formula (III) and stirring, and removing the solvent after the reaction to obtain a benzofuranone chitosan complex represented by the structural formula (II).

6. The method for preparing the benzofuranone chitosan composite according to claim 5, characterized in that: The mass ratio of chitosan and the benzofuranone derivative represented by the structural formula (I) is 1g:(0.01-0.5)g, The molecular weight of the chitosan is 30,000 to 80,000, and the chitosan is added to the acetone solution of the compound represented by the structural formula (III) at a concentration of 0.2 to 2 g / L.

7. Use of the benzofuranone chitosan complex according to claim 1 in building anti-corrosion, historical building protection, and old housing renovation.

8. The use according to claim 7, characterized in that: The benzofuranone chitosan complex shown in structural formula (II) is used to treat wood or wood composite materials in buildings to inhibit the growth of fungi that cause wood decay, including white rot fungi, brown rot fungi, discoloration fungi, and soft rot fungi.

9. A building material antibacterial composition, characterized in that Contains the benzofuranone chitosan composite according to claim 1.

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