General description

The 2,7-Dihydroxy-9-fluorenone is a chemical compound with the molecular formula C13H803. It has two hydroxy groups (-OH) located at positions 2 and 7 of the fluorenone ring system, which consists of two fused benzene rings and a ketone group(C=O).This compound is often used as an intermediate in organic synthesis to produce other more complex compounds. It can also be found in some plant species and has been studied for its potential antioxidant and anticancer properties.

Figure 1: the Physical picture of 2,7-Dihydroxy-9-fluorenone

Application

The 2,7-Dihydroxy-9-fluorenone is an important pharmaceutical intermediate and functional monomer for materials, it can be used in the pharmaceutical industry to synthesize anti-tumor and sympathetic nerve inhibitors; Used in agriculture to synthesize herbicides and insecticides; In the plastic industry, bisphenol products can be synthesized as stabilizers and plasticizers in the polymerization process, and functional polymer materials can be produced; In the field of liquid crystal materials, it can be used to synthesize new organic compounds that are prone to produce mesomorphic phenomena, showing good application prospects[2]. As a structural unit of macrocyclic receptors for polar organic substrates, fluorenone fragments have the function of expanding and polarizing the electronic system. Macrocyclic structural substances that introduce polar aromatic units can enhance electrostatic interactions and the binding force of polar substrates. Therefore, this substance is widely used as catalysts, ionic and neutral molecular carriers, chemical sensors, and supramolecular structural components such as rotaxanes and alkenes, The latter can be applied in the infrastructure design of nano electronic devices. As a pharmaceutical intermediate with good drug activity, fluorenone is mainly used for viral interferon, sympathetic nerve inhibitors, antispasmodic agents, anticancer drugs, etc.

Preparation

The second figure shows the preparation of 2,7-Dihydroxy-9-fluorenone. Add a certain amount of concentrated sulfuric acid (H2SO4) to a three-necked bottle with mechanical stirring, reflux condensing tube, and thermometer, place it in an electric heating jacket to heat to reaction temperature.

Add Slowly a certain amount of fluorene (I) to the three-necked bottle while stirring, vigorously stirring for a certain time. After the reaction is completed, cool it and add it to ice water to completely dissolve it and filter it. Pour the filtrate into a beaker, raise the temperature to 50 ℃, add a certain amount of potassium chloride (KCl), keep it warm and stir for 30 minutes. After cooling, filtering, add a certain amount of water to the filter cake, adjust the pH of the solution to 7-8 with potassium carbonate (K2CO3), and recrystallize to obtain 2,7-dipotassium fluorene sulfonate(Ⅱ). Add a certain amount of II, water, and catalyst to a four necked bottle with a stirring, reflux condensing tube, vent tube, and thermometer in turn, turn on the stirring, raise the temperature to the reaction temperature, continuously inject oxygen into the reaction system, keep the reaction warm for a period of time, stop the injection of oxygen, and lower the temperature. Concentrate the reaction solution to a certain volume, freeze the concentrated solution, filter and collect the filter cake, and dry it to obtain 2,7-dipotassium sulfo-9-fluorenone (III). Add a certain amount of flaky sodium hydroxide (NaOH) into a high-temperature reactor, and heat it until the NaOH is molten. Slowly add a certain amount of III to it in batches while stirring. After adding the material and reacting for a period of time, the reaction can be stopped until there are no bubbles emerging from the reaction liquid. The reaction liquid was naturally cooled to room temperature. After cooling, add a certain amount of water, stir until it is completely dissolved, and filter through suction. Transfer the filtrate to a beaker. Add concentrated hydrochloric acid into it to adjust the pH ≤ 2. A large amount of solids are precipitated. Filter through suction, wash the filter cake with water to neutral, and dry to obtain 4,4 '- dimethylbiphenyl-2-carboxylic acid (Ⅳ). Dissolve a certain amount of Lewis acid type catalyst in a certain amount of water, adjust the pH value of the system to below 2 with concentrated hydrochloric acid, fully dissolve it, add a certain amount of Ⅳ, stir with a magnetic stirrer, make it evenly dispersed, dehydrate with a rotary evaporator, place it in a vacuum drying box that rises to the specified reaction temperature, and react for a period of time. After the reaction is completed, it is lowered to room temperature, fully dissolved with water, and then adjusted to a pH value below 2 with concentrated hydrochloric acid. After filtration, the filtrate is collected, and the filter cake is washed with water and 95% ethanol in turn. The filter cake is vacuum dried to obtain the product.

Figure 2: preparation of 2,7-Dihydroxy-9-fluorenone

References

1. Ivanov A V, LyakhovS A, YarkovaM Y, et al. Synthesis and Liquid Crystal Properties of2,7-Dialkoxy-9-fluorenones[J]. Russian Journal of General Chemistry，2002,72(9):1435-1438.

2. Luo J D, Haller M, Li H X, et al. A Side-Chain Dendronized Nonlinear Optical Polyimide with Large and Thermally Stable Electrooptic Activity[J]. Macromolecules,2004,37:248-250.

3. Yang WY. Synthesis process and process design of 2,7-dihydroxy-9-fluorone [D]. Wuhan University of Technology, 2015.