Chrysophanic acid, also known as 1,8-dihydroxy-3-methyl-9,10-anthracenedione, is a yellow crystalline substance with strong dyeing properties and mild antibacterial properties. Its chemical formula is C15H10O4, which is an organic compound, which is chemically active. Slightly soluble in water, more easily soluble in ethanol and ether. It oxidizes easily and decomposes when heated. It can react with water, sodium hydroxide and potassium iodate, etc. The molecule of Chrysophanic acid contains two hydroxyl groups and one carbonyl group, so it has some typical hydroxyl and carbonyl reactions. For example, it can react with ammonia to form fumarate, and it can react with nitrous acid to produce quinolines.
Chemical reaction of Chrysophanic acid:
(1) Chrysophanic acid reacts with oxidizing agents: Chrysophanic acid can react with oxidizing agents such as hydrogen peroxide and sodium chlorate to generate derivatives with higher oxidation states, such as montmorillonite acid and dalianic acid.
(2) Chrysophanic acid reacts with ammonia: Chrysophanic acid reacts with ammonia to generate fumarate, which is a kind of highly permeable molecule and is also widely used in cell culture, life science research and other fields.
(3) Chrysophanic acid reacts with nitrous acid: Chrysophanic acid reacts with nitrous acid to form a compound with a quinoline structure, which has the effect of inhibiting mycelium growth and bactericidal.
The synthesis method of Chrysophanic acid:
1. Extraction from bark or ambiguous plants: This was the most widely used method before. It requires complex preparation steps such as distillation and purification of plants, and the cost is relatively high.
Specific steps are as follows:
(1.) Pretreatment of bark or plant samples: First, the dried bark or plant material is crushed and sieved (approximately 20 mesh). Then take 50g of powder sample, add 800ml of sodium hydroxide (NaOH) (0.5M) and 200ml of water, mix well
(2.) Extraction of Chrysophanic acid: Heat the mixture to 70°C and use a stirrer to stir it evenly. Add 300 mL of ethanol to dissolve and continue stirring for 30 minutes. When the mixture was cooled to room temperature, 300 ml of n-hexane was added and stirred for 5 minutes. The mixture was then left for 10 minutes, the n-hexane phase was separated off and the operation was repeated. Transfer all of the n-hexane phase to a collecting flask. The Chrysophanic acid content in the mixture is about 4mg/ml.
(3.) Separation and purification by chloroform column chromatography: the Chrysophanic acid n-hexane phase was transferred to a beaker and evaporated. The resulting residue was dissolved with a small amount of chloroform. Then, it was separated and purified by passing through a 10 cm long, 1 cm diameter silica gel column. Perform column chromatography layer by layer using chloroform/ethyl acetate (3:1) as the eluent with 5 mL per layer. Gather the overlay of Chrysophanic acid. Finally, it was dissolved with chloroform/methanol mixture to obtain purified Chrysophanic acid. Collect these liquids and store them in small test tubes or other airtight containers to obtain high-quality Chrysophanic acid.
In conclusion, the above is a highly efficient method to extract Chrysophanic acid from bark or fuzzy plants. This method is simple and efficient, does not require expensive reagents and equipment, and can produce high-quality Chrysophanic acid in large quantities, providing effective raw materials for subsequent drug and biological research.
2. Synthesis method: Synthesis method is currently one of the most widely used methods for preparing Chrysophanic acid. Common synthetic methods include the Ball-Smitt reaction and epoxidation reaction.
2.1 Ball-Smit reaction:
The Ball-Smit reaction is to use benzaldehyde and acetic acid to react with dilute sulfuric acid to generate benzaldehyde derivatives, and then heat the derivatives to a certain temperature to react with formaldehyde to obtain intermediate product 2, and then use oxidants such as nitric acid and nitrous acid to act Chrysophanic acid is formed.
The following are specific instructions:
(1.) First, we need to prepare the required materials and chemical reagents. We need chemicals such as resorcinol (1,2-dihydroxybenzene), highly toxic chemicals isocyanate and hydrazine hydrate, sodium iodate, disodium persulfate, corn oil, concentrated sodium hydroxide, acetic acid, and chloroform. These chemical reagents are common raw materials and reagents in the laboratory.
(2.) In the experiment, we first need to carry out the first step in the Paul-Smitt reaction: the synthesis of p-disubstituted phenol. This can be done by mixing resorcinol with isocyanate and hydrazine hydrate and reacting at room temperature for 8-12 hours. At this time, we need to pay attention to controlling the temperature, and it must not exceed 40°C, otherwise side reactions may occur.
(3.) After the first step is done, we need to convert it into 1,8-naphthalene dioxide. This process requires the addition of sodium iodate and disodium persulfate. When these two chemical reagents are formed in the reaction, it is necessary to heat the reaction to a water bath supply. At the end of the reaction, the 1,8-naphthalene dioxide can only be obtained by extraction.
(4.) After getting 1,8-naphthalene dioxide, we need to redissolve it in corn oil, then add it to 1.5M sodium hydroxide to start its conversion into Chrysophanic acid. This reaction requires heating at 70°C for 90 minutes to complete. At this time, we need to control the temperature and not let the temperature exceed 70°C, otherwise the conversion rate may decrease.
(5.) In the last step, we need to do the extraction for the Chrysophanic acid. At this point, we use concentrated acetic acid and chloroform for extraction. Next, we further concentrated the extracted Chrysophanic acid by a rotary vacuum evaporator to obtain a purer product.
The above is the process of synthesizing Chrysophanic acid from the detailed steps of the synthesis method Ball-Smit reaction. It should be noted that during the experiment, we need to master the temperature, reaction time and the amount of chemical reagents used in each step in order to obtain better products.
2.2 Epoxidation reaction:
The reactant of epoxidation reaction is mainly 2-hydroxy-1,4-naphthoquinone. The reaction uses hydrogen peroxide or chromium trioxide to oxidize 2-hydroxy-1,4-naphthoquinone to generate an oxidant, and then undergoes an epoxidation reaction to obtain Chrysophanic acid.
detailed steps:
(1.) Raw material preparation:
The synthesis of Chrysophanic acid requires the following raw materials: anthraquinone, maleic anhydride, benzene, sulfuric acid, hypochlorous acid and sodium hydroxide, etc. These ingredients should be accurately weighed and prepared.
(2.) Preparation of epoxidation reaction:
Starting from anthraquinone, 1,2-dihydroanthraquinone was prepared by catalytic hydrogenation of benzene; then, it was reacted with isopropanol and maleic anhydride to prepare epoxy compounds.
(3.) Improvement of epoxidation reaction:
An improved epoxidation reaction method is sulfonation modified epoxidation reaction. 1,2-dihydroanthraquinone is precipitated in sulfuric acid, which is then reacted with sodium nitrite to generate N-nitro-1,2-dihydroanthraquinone. Finally, the product is diluted with base and reacted to form epoxy compounds.
(4.) Remedy:
When the epoxidation reaction conditions are not suitable, the yield may decrease. In order to solve this problem, some of the following remedial measures can be taken:
(4.1) Change the reaction system: try different catalysts and solvents to find the optimal reaction conditions.
(4.2) Changing the reaction time: shortening or prolonging the reaction time may affect the yield of the product.
(4.3) Changing the reaction temperature: lowering the reaction temperature can reduce the formation of by-products and increase the product yield.
In conclusion, the synthesis of Chrysophanic acid requires epoxidation reaction as a key step. The traditional method requires the catalytic hydrogenation of anthraquinone with benzene to prepare 1,2-dihydroanthraquinone, which is then reacted with maleic anhydride to prepare epoxy compounds. An improved method is the sulfonation-modified epoxidation reaction. However, the yield may be limited by the reaction conditions, and some measures need to be taken to improve the reaction.
In short, as a compound widely used in clinical medicine, chemistry, biology and other fields, Chrysophanic acid has many chemical properties and reaction characteristics, and its synthesis method is also constantly developing and improving.