Polyaldehyde organic monomers based on siloxyl compounds and methods for their preparation

Abstract

The siloxy compound-based polyaldehyde organic monomer and a preparation method thereof belong to the technical field of organic synthesis. The siloxy compound-based polyaldehyde organic monomer is synthesized by taking aromatic siloxy compounds as substrates and through two-step reactions, and includes single-silicon monomers and double-silicon monomers, and the purity of the monomers can reach more than 96%. The polyaldehyde organic monomer can be used as a reaction substrate to synthesize porous organic polymer materials through Schiff base polycondensation reactions. The present application solves the problems of difficult synthesis of polyaldehyde aromatic organic monomers, more by-products, limited designable types and the like. The method can obtain polyaldehyde organic monomers with high purity, provides an important basis for subsequent design and synthesis of some porous organic polymer materials with new structures and new functions, and reduces the cost of porous organic polymers.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, specifically involving two polyaldehyde organic monomers (including monosilicon monomers and disilicon monomers) based on silanoxy compounds and their preparation methods. Background Technology

[0002] Since the 21st century, crystalline or amorphous porous organic polymer materials have become a new type of porous material. Among them, crystalline porous organic polymer materials are also known as covalent organic frameworks (COFs), which have a wide range of potential applications in separation, storage, catalysis, sensing, and drug sustained release. Schiff base reaction is one of the most common polymerization reactions for constructing porous organic polymer materials, especially covalent organic frameworks. One of the prerequisites for polymerizing porous organic polymer materials through Schiff base reaction is to obtain aromatic organic monomers with polyaldehyde groups. The synthesis of aromatic organic monomers with polyaldehyde groups is usually carried out through the following two routes: (1) First, a brominated intermediate is obtained, and then the brominated intermediate is subjected to halide lithium exchange with an organolithium reagent, and then reacted with N,N'-dimethylformamide to convert the brominated site into an aldehyde group; (2) Boric acid or borate ester with aldehyde groups is used as a precursor, and monomers containing aromatic aldehydes are obtained by coupling through Suzuki-Miyaura reaction. Both of these methods have their own advantages, disadvantages and limitations. The advantage of method (1) is that the intermediate is relatively easy to obtain, but its success depends on the activity of the brominated intermediate. Moreover, it has high requirements for the anhydrous and oxygen-free synthesis environment, reactants and solvents. Especially when synthesizing products with more than three aldehyde groups, the brominated sites often cannot be completely converted into aldehyde groups, resulting in many byproducts with similar properties that are difficult to separate. Method (2) is relatively mature and efficient, and is also one of the commonly used methods in the literature. However, it cannot simply introduce aldehyde groups, but requires the introduction of aldehyde groups with benzene rings. This results in longer branched chains of the designed and synthesized multi-aldehyde organic monomers, larger monomer molecules, and poor solubility, which increases the difficulty of subsequent Schiff base polymerization to synthesize porous organic polymers.

[0003] Currently, companies such as Jilin Zhongke Science & Technology Co., Ltd., Jinan Henghua Technology Co., Ltd., Shanghai Kaishu Chemical Technology Co., Ltd., and Shanghai Tengqian Biotechnology Co., Ltd. have all developed and produced various polyaldehyde-containing aromatic organic monomers, which are sold to research institutions for constructing porous organic polymer materials. The polyaldehyde-containing organic monomers provided by this invention have excellent properties and can also be used in the construction of porous organic polymer materials. Summary of the Invention

[0004] The objective of this invention is to provide a novel synthetic method—a method for synthesizing silicon-centric, polyaldehyde-containing organic monomers (including monosilicon monomers and disilicon monomers) through a two-step reaction using aromatic silaneoxy compounds as substrates, and to synthesize two novel polyaldehyde aromatic organic monomers using this method. This objective is achieved as follows:

[0005] (1) Synthesis of a single-silicon-centered trialdehyde-based organosilicon monomer (single-silicon monomer):

[0006]

[0007] In the organosilicon substrate, R1 can be any one of the following groups:

[0008]

[0009] In the organosilicon substrate, R2 can be either methyl or ethyl.

[0010] (2) Synthesis of a disilicon-centered hexaaldehyde-based organosilicon monomer (disilicon monomer):

[0011]

[0012] In the organosilicon substrate, X can be any one of the following groups:

[0013]

[0014] Preferably, the organic monomers containing multiple aldehyde groups centered on silicon atoms obtained in this invention are monosilicon trialdehyde monomer compound 1 and disilicon hexaaldehyde monomer compound 2, and their structural formulas are shown below:

[0015]

[0016] The present invention discloses a method for preparing a silicon-centered organic monomer containing multiple aldehyde groups from an aromatic silanoxy compound, the steps of which are as follows:

[0017] (1) In an inert gas atmosphere, add 7.6 mmol of 4-bromobenzaldehyde dimethyl acetal and 20-300 mL of anhydrous tetrahydrofuran (dried with sodium sand) to a Schlenk flask and mix well, then cool to -100 to 0℃.

[0018] (2) Slowly add 7.6 to 15.2 mmol of n-butyllithium solution (solvents such as hexane, heptane, petroleum ether, benzene, toluene, xylene, etc.) to the reaction system obtained in step (1) using a syringe, and react at -100 to 0°C for 1 to 4 hours;

[0019] (3) Add 1-4 mmol of organosilicon substrate to the reaction system obtained in step (2), react at -100 to 0°C for 1-4 hours, then return to room temperature and stir overnight;

[0020] (4) Add 5-20 mL of distilled water to the reaction system obtained in step (3) to quench the reaction, then extract with 30-100 mL of ethyl acetate 3-5 times, combine the organic phases, dry with anhydrous sodium sulfate, distill the organic phase under reduced pressure, and then perform column chromatography with ethyl acetate and petroleum ether to obtain the intermediate product.

[0021] (5) Dissolve the intermediate product obtained in step (4) in 30-100 mL of dichloromethane, then add 10-50 mL of trifluoroacetic acid and stir overnight at room temperature;

[0022] (6) Add saturated sodium bicarbonate solution to the reaction system obtained in step (5) to neutralize to pH=7, then extract with 30-100 mL of ethyl acetate 3-5 times, combine the organic phases, dry with anhydrous sodium sulfate, and distill the organic phase under reduced pressure to obtain the silicon-centered polyaldehyde organic monomer of the present invention.

[0023] In summary, this invention synthesizes organosilicon monomers containing multiple aldehyde groups through a simpler and lower-cost method, achieving a purity of over 96%. This enriches the methods for synthesizing organic monomers that can be used to prepare porous organic polymers, and provides an important foundation for designing and synthesizing porous organic polymer materials with novel structures and functions, as well as reducing the cost of porous organic polymers. Attached Figure Description

[0024] Figure 1 Compound 1 1 H-NMR spectrum;

[0025] Figure 2 Compound 1 13 C-NMR spectrum;

[0026] Figure 3 Compound 2 1 H-NMR spectrum;

[0027] Figure 4 Compound 2 13 C-NMR spectrum;

[0028] Figure 5 Nitrogen adsorption diagram at 77 K for covalent organic framework compound 3;

[0029] From the above attached figures, i.e., compounds 1 and 2 at 300M 1 H-NMR and 13In C-NMR, it can be confirmed that we have successfully obtained target compounds 1 and 2, and the purity of the silicon-centered organic monomers containing multiple aldehyde groups prepared by this method can reach more than 96%. Figure 5 The image shows the nitrogen adsorption diagram at 77 K for compound 3, a covalent organic framework obtained by polymerizing compound 2 with p-phenylenediamine. It is evident that compound 2 has the potential to construct porous organic polymers. The monosilicon-centered trialdehyde organic monomer and the disilicon-centered hexaaldehyde organic monomer prepared in this invention can be used as planar three-node and inverse triangular prism six-node structural blocks, respectively, to construct covalent organic framework materials. Combined with other functional structural blocks, they can be used to directionally synthesize novel porous materials with multifunctional and novel topological structures, showing potential applications in separation, storage, catalysis, sensing, and drug delivery. The preparation method of this invention enriches the methods for obtaining organic monomers that can be used to prepare porous organic polymers, providing an important foundation for designing and synthesizing porous organic polymer materials with novel structures and functions, as well as reducing the cost of porous organic polymers. Detailed Implementation

[0030] Example 1: Preparation of a single-silicon-centered trialdehyde-based organosilicon monomer

[0031] (1) In an inert gas atmosphere, add 7.6 mmol of 4-bromobenzaldehyde dimethyl acetal and 150 mL of anhydrous tetrahydrofuran (dried with sodium sand) to a Schlenk flask and mix well, then cool to -78°C.

[0032] (2) Slowly add 3.1 mL of 2.5 M n-butyllithium solution (solvent is n-hexane) to the reaction system obtained in step (1) using a syringe, and react at -78 °C for 2 hours;

[0033] (3) Add 2.5 mmol of phenyltriethoxysilane to the reaction system obtained in step (2), react at -78°C for 2 hours, then restore to room temperature and stir overnight;

[0034] (4) Add 10 mL of distilled water to the reaction system obtained in step (3) to quench the reaction, then extract with 50 mL of ethyl acetate three times, combine the organic phases, dry with anhydrous sodium sulfate, distill the organic phase under reduced pressure, and then perform column chromatography with ethyl acetate and petroleum ether to obtain the intermediate product.

[0035] (5) Dissolve the intermediate product obtained in step (4) in 30 mL of dichloromethane, then add 10 mL of trifluoroacetic acid and stir overnight at room temperature;

[0036] (6) Add saturated sodium bicarbonate solution to the reaction system obtained in step (5) to neutralize to pH=7, then extract three times with 50 mL of ethyl acetate, dry with anhydrous sodium sulfate, and distill the organic phase under reduced pressure to obtain the organic monomer containing polyaldehyde groups with silicon atoms as the center of the present invention. The product mass is 550 mg.

[0037] Example 2: Preparation of a hexaldehyde-based organosilicon monomer with a dual-silicon center

[0038] (1) In an inert gas atmosphere, add 7.6 mmol of 4-bromobenzaldehyde dimethyl acetal and 150 mL of anhydrous tetrahydrofuran (dried with sodium sand) to a Schlenk flask and mix well, then cool to -78°C.

[0039] (2) Slowly add 3.1 mL of 2.5 M n-butyllithium solution (solvent is n-hexane) to the reaction system obtained in step (1) using a syringe, and react at -78 °C for 2 hours;

[0040] (3) Add 1.26 mmol of 1,4-triethoxysilylbenzene to the reaction system obtained in step (2), react at -78°C for 2 hours, then restore to room temperature and stir overnight;

[0041] (4) Add 10 mL of distilled water to the reaction system obtained in step (3) to quench the reaction, then extract with 50 mL of ethyl acetate three times, combine the organic phases, dry with anhydrous sodium sulfate, distill the organic phase under reduced pressure, and then perform column chromatography with ethyl acetate and petroleum ether to obtain the intermediate product.

[0042] (5) Dissolve the intermediate product obtained in step (4) in 30 mL of dichloromethane, then add 10 mL of trifluoroacetic acid and stir overnight at room temperature;

[0043] (6) Add saturated sodium bicarbonate solution to the reaction system obtained in step (5) to neutralize to pH=7, extract three times with 50 mL of ethyl acetate, combine the organic phases, dry with anhydrous sodium sulfate, and distill the organic phase under reduced pressure to obtain the organic monomer containing polyaldehyde groups with silicon atoms as the center of the present invention. The product mass is 690 mg.

[0044] Example 3: Synthesis of porous organic polymer materials using organosilicon monomer compound 2

[0045] (1) Compound 2 (20.0 mg, 0.026 mmol) and p-phenylenediamine (8.5 mg, 0.078 mmol) were added to an ampoule;

[0046] (2) Add 1.0 mL of 1,4-dioxane and 1.0 mL of mesitylene to the reaction system obtained in step (1), and sonicate for 30 minutes to obtain a yellow turbid liquid;

[0047] (3) Add 0.2 mL of 6 M acetic acid aqueous solution to the reaction system obtained in step (2);

[0048] (4) Freeze the reaction system obtained in step (3) with liquid nitrogen, then use an oil pump to evacuate the system to make the pressure inside the ampoule reach 0 mbar, then fill it with nitrogen, and then evacuate it again. Repeat this process three times.

[0049] (5) After sealing the ampoule of the reaction system obtained in step (4) with a flame gun, place it in an oven and heat it at 120°C for 72 hours to obtain 23 mg of solid, with a yield of 90%.

[0050] (6) The solid obtained in step (5) was washed with tetrahydrofuran by Soxhlet extraction for 48 hours and dried at 100°C for 12 hours to obtain covalent organic framework material compound 3, and nitrogen adsorption test was performed at 77K.

Claims

1. A polyaldehyde organic monomer based on silanoxy compounds, the structural formula of which is shown below: 。 2. A method for preparing a polyaldehyde organic monomer based on a silanoxy compound as described in claim 1, comprising the following steps: (1) Under an inert gas atmosphere, mix 7.6 mmol of 4-bromobenzaldehyde dimethyl acetal and 20~300 mL of anhydrous tetrahydrofuran evenly, and then cool to -100~0 °C; (2) Slowly add 7.6~15.2 mmol n-butyllithium solution to the reaction system obtained in step (1) using a syringe, and react at -100~0 °C for 1~4 hours; (3) Add 1-4 mmol of organosilicon substrate to the reaction system obtained in step (2), react at -100 to 0 °C for 1-4 hours, then return to room temperature and stir overnight; The structural formula of the organosilicon substrate is shown below. ； X is R2 is a methyl group; (4) Add 5-20 mL of distilled water to the reaction system obtained in step (3) to quench the reaction, then extract with 30-100 mL of ethyl acetate 3-5 times, combine the organic phases, dry with anhydrous sodium sulfate, distill the organic phase under reduced pressure, and then perform column chromatography with ethyl acetate and petroleum ether to obtain the intermediate product. (5) Dissolve the intermediate product obtained in step (4) in 30-100 mL of dichloromethane, then add 10-50 mL of trifluoroacetic acid and stir overnight at room temperature; (6) Add saturated sodium bicarbonate solution to the reaction system obtained in step (5) to neutralize to pH=7, then extract with 30~100 mL of ethyl acetate 3~5 times, combine the organic phases, dry with anhydrous sodium sulfate, and distill the organic phase under reduced pressure to obtain a polyaldehyde organic monomer based on silanoxy compounds with silicon atoms as the center.

3. The preparation method according to claim 2, characterized in that: The solvents used in n-butyllithium solutions are hexane, heptane, petroleum ether, benzene, toluene, or xylene.

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