A benzazepine-containing doPO derivative, and a preparation method and application thereof

Abstract

The application relates to a novel DOPO derivative containing a benzazepine and preparation and application thereof, and belongs to the field of polymer synthesis. The application provides a novel DOPO derivative containing a benzazepine, a structural general formula of which is shown as formula I, wherein R 1 , R 2 are various structure alkyl, cycloalkyl with 3-6 carbon atoms, alkenyl with 2-6 carbon atoms, aryl alkenyl with 8-12 carbon atoms, aryl or hydrogen; X is a heteroatom such as N, O or S. The obtained novel DOPO derivative containing a benzazepine can be used as an organic synthesis intermediate, is an excellent flame retardant which can realize high flame retardation in epoxy resin, polyurethane, polyester, polyamide and other high polymer materials through low addition amount due to excellent thermal stability and multiple flame retardation elements.

Description

Technical Field

[0001] This invention relates to a novel DOPO derivative containing benzo[a]azapyrrolizidine, its preparation and application, and belongs to the field of polymer synthesis. Background Technology

[0002] Epoxy resin, as an important thermosetting material, possesses excellent adhesion, wear resistance, mechanical properties, electrical insulation properties, chemical stability, high and low temperature resistance, dimensional stability, ease of processing and molding, and low cost, making it widely used in military and civilian applications. However, its flammability limits its wider application; epoxy resin itself is flammable and can drip flammable droplets, igniting underlying materials. With increasing demands for flame retardant performance in electronic and electrical products, research on flame retardant modification is receiving increasing attention. Halogenated flame retardants were commonly used in the past, but with the growing toxicity and harmfulness of halogenated flame retardants, organophosphorus flame retardants have become increasingly popular among halogen-free flame retardants due to their high efficiency, low toxicity, and environmental friendliness.

[0003] 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), as an intermediate in additive phosphine-containing flame retardants, contains biphenyl and phenanthrene rings in its molecular structure, as well as active phosphorus-hydrogen bonds, enabling it to react with olefin, epoxy, and carbonyl compounds to generate derivatives with unique properties. However, DOPO and its derivatives have poor thermal stability and are prone to melting and degradation during high-temperature processing, failing to meet the processing temperatures of most polymer materials. Furthermore, high addition amounts of additive flame retardants often damage the mechanical properties of the substrate. While Chinese patent CN104086593 proposes a DOPO-derived flame retardant prepared from aryl ketones and DOPO-like compounds under an acidic catalyst, this compound exhibits good thermal stability, but its flame retardant performance is not outstanding; an addition of 17% wt is required to achieve the UL94V-0 rating. Therefore, designing and developing a DOPO-derived flame retardant with good thermal stability and high flame retardancy at low addition amounts is a promising direction for application. Summary of the Invention

[0004] To address the aforementioned deficiencies, this invention provides a novel DOPO-derived flame retardant containing benzo[b,f][1,4]azaphenanthrene-11-yl]dibenzo[c,e][1,2]oxa-phosphaphenanthrene-6-oxide (DBDs), along with its simple preparation method and applications. The resulting novel DOPO derivative containing benzo[b,f][1,4]azaphenanthrene-11-yl]dibenzo[c,e][1,2]oxa-phosphaphenanthrene-6-oxide is not only suitable as an organic synthesis intermediate but also, due to its excellent thermal stability and abundance of flame-retardant elements, is a superior flame retardant for use in epoxy resins, polyurethanes, polyesters, polyamides, and other polymeric materials. Adding this flame retardant enables polymeric materials to achieve excellent flame-retardant properties (limiting oxygen index ≥30%, and passing UL94V-0 vertical burning test) even with low phosphorus content (≤0.5%).

[0005] The technical solution of this invention:

[0006] The first technical problem to be solved by this invention is to provide a novel DOPO derivative containing benzo[a]azapyrrolizidine, the general structural formula of which is shown in Formula I:

[0007]

[0008] In formula I, R 1 R 2 It can be an alkyl group of various structures (straight-chain or branched alkyl groups of C1 to C30), a cycloalkyl group with 3 to 6 carbon atoms, an alkenyl group with 2 to 6 carbon atoms, an aryl alkenyl group with 8 to 12 carbon atoms, an aryl group (straight-chain or branched aryl groups of C6 to C30 and aryl groups containing alkyl, carboxyl, naphthyl, thiophene, furanyl, hydroxyl, cyano, amino, nitro, dimethylamino substituents) or hydrogen; X is a heteroatom such as N, O or S.

[0009] Furthermore, the R 1 R 2 Selected from: methyl, methoxy, ethyl, ethoxy, propyl, isopropyl, butyl, vinyl, ethynyl, phenyl, benzyl, phenoxy, styryl, amino, naphthyl, thiophene, furanyl, hydroxyl, mercapto, dimethylamino, or indoleyl, etc. Preferably hydrogen, vinyl, methyl, methoxy, amino, hydroxyl, ethyl, ethoxy, phenyl, benzyl, or phenoxy.

[0010] Furthermore, the structural formula of the novel DOPO derivative containing benzozazepine is as follows:

[0011]

[0012] Where X = N, O, or S.

[0013] The second technical problem to be solved by the present invention is to provide a method for preparing the compound shown in Formula I. The method is as follows: a benzozazepine compound, a DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) compound and an organic solvent are added to a reaction vessel, stirred evenly at room temperature, and then refluxed at 60-150°C for 2-12 hours. After the reaction is completed, the compound shown in Formula I (DBDs) is obtained by filtration and drying.

[0014] Furthermore, the mass ratio of the benzo[a]azapyridine compound to the DOPO compound is 1:0.7-2.

[0015] Furthermore, the DOPO compounds are DOPO and DOPO derivatives.

[0016] Furthermore, the organic solvent includes polar solvents, alcohol solvents, ether solvents, sulfone solvents, or aromatic solvents.

[0017] Furthermore, the organic solvent is selected from: alcohol solvents such as methanol or ethanol; ether solvents such as anisole, diethyl ether, and 1,4-dioxane; sulfone solvents such as dimethyl sulfoxide; aromatic solvents such as toluene or benzene; halogen-containing polar solvents such as dichloromethane and chloroform; aromatic polar solvents such as xylene, pyridine, or chlorobenzene; nitrile solvents such as acetonitrile or propionitrile; and amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; preferably pyridine, anisole, chlorobenzene, and N,N-dimethylformamide.

[0018] The volume ratio of the organic solvent added to the mass ratio of the DOPO compound is 1-4 mL: 1 g.

[0019] Furthermore, the benzozazepine compound is prepared by the following method: [The following is a description of a specific compound with the structural formula...] aniline, with the structural formula as follows The benzo[a]benzaldehyde, alkali and organic solvent are stirred evenly at 0-25°C, and then reacted at 40-200°C for 2-10 hours. After the reaction is completed, the benzo[a]azapyridine compound is obtained by washing, filtering, purifying and drying. Wherein, Z = OH, SH or NH2, Y = F, Cl, Br or I.

[0020] Furthermore, the structural formula is as follows: In aniline, the aryl substituent R 2 Alkyl groups of various structures (C1-C5) 30 Straight-chain or branched alkyl groups, cycloalkyl groups having 3 to 6 carbon atoms, alkenyl groups having 2 to 6 carbon atoms, aryl alkenyl groups having 8 to 12 carbon atoms, aryl (C6-C) groups 30Straight-chain or branched aryl groups and aryl groups containing alkyl, carboxyl, naphthyl, thiophene, furanyl, hydroxyl, cyano, amino, nitro, dimethylamino substituents) or hydrogen; Z = OH, SH or NH2.

[0021] Furthermore, the structural formula is as follows: In o-halobenzaldehyde, R 1 It can be an alkyl group of various structures (straight-chain or branched alkyl groups of C1 to C30), a cycloalkyl group with 3 to 6 carbon atoms, an alkenyl group with 2 to 6 carbon atoms, an aryl alkenyl group with 8 to 12 carbon atoms, an aryl group (straight-chain or branched aryl groups of C6 to C30 and aryl groups containing alkyl, carboxyl, naphthyl, thiophene, furanyl, hydroxyl, cyano, amino, nitro, or dimethylamino substituents) or hydrogen; Y = F, Cl, Br or I.

[0022] Furthermore, in the above-mentioned method for preparing benzozazepine compounds, the structural formula is as follows: aniline, with the structural formula as follows The molar ratio of o-halobenzaldehyde to the base is 1:0.8~1.5:0.8~1.5.

[0023] Preferably, the structural formula is as follows: The substance indicated by (o-mercapto, o-hydroxy, or o-aminoaniline) is selected from: 2-hydroxyaniline, 2-mercaptoaniline, or 2-aminoaniline.

[0024] Preferably, the structural formula is as follows: The o-halobenzaldehyde is selected from: o-fluorobenzaldehyde, o-chlorobenzaldehyde, 3-methyl o-fluorobenzaldehyde, 3-methoxy o-fluorobenzaldehyde, 3-methyl o-chlorobenzaldehyde, or 3-methoxy o-chlorobenzaldehyde.

[0025] Furthermore, in the preparation method of the benzozazepine compounds, the organic solvent includes polar solvents, alcohol solvents, ether solvents, sulfone solvents, or aromatic solvents.

[0026] Furthermore, the organic solvent is selected from: alcohol solvents such as methanol or ethanol; ether solvents such as anisole, diethyl ether, and 1,4-dioxane; sulfone solvents such as dimethyl sulfoxide; aromatic solvents such as toluene or benzene; halogen-containing polar solvents such as dichloromethane and chloroform; aromatic polar solvents such as xylene, pyridine, or chlorobenzene; nitrile solvents such as acetonitrile or propionitrile; and amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; preferably pyridine, anisole, chlorobenzene, and N,N-dimethylformamide.

[0027] Furthermore, in the above-mentioned method for preparing benzo[a]azapyrrolizidine compounds, the organic solvent and the organic solvent with the structural formula […]. The ratio of aniline used is 2-10 mL: 1 g.

[0028] Furthermore, the alkali includes: organic alkalis such as sodium methoxide, triethylamine, pyridine, sodium ethoxide, potassium tert-butoxide, sodium tert-butoxide, potassium bis(trimethylsilyl)amino, lithium bis(trimethylsilyl)amino, sodium bis(trimethylsilyl)amino, and lithium tert-butyl; or: various inorganic alkalis such as sodium hydride, sodium hydroxide, potassium hydroxide, and cesium carbonate; preferably potassium carbonate, sodium carbonate, or sodium hydroxide.

[0029] The third technical problem to be solved by the present invention is to provide the use of the above-mentioned DOPO derivatives in intermediates, flame retardants or pharmaceuticals.

[0030] Furthermore, the DOPO derivative is used as a flame retardant in polymer materials such as epoxy resin, polyurethane, polyester, or polyamide.

[0031] The fourth technical problem to be solved by the present invention is to provide a flame-retardant epoxy resin material, wherein the raw materials of the flame-retardant epoxy resin material include DOPO derivatives shown in Formula I.

[0032] Furthermore, in the flame-retardant epoxy resin material, the amount of the DOPO derivative shown in Formula I added is 1 to 10 wt% of the flame-retardant epoxy resin material; preferably 1 to 5 wt%.

[0033] Furthermore, the raw materials and their proportions for the flame-retardant epoxy resin material are as follows: 30-48 parts by weight of bisphenol A diglycidyl ether, 5-14 parts by weight of diaminodiphenylmethane, and 1-4 parts by weight of the flame retardant shown in Formula I.

[0034] Furthermore, when the amount of flame retardant added is 4 wt%, the limiting oxygen index of the flame retardant epoxy resin material is 38%.

[0035] The fifth technical problem to be solved by the present invention is to provide a transparent flame-retardant epoxy resin material, wherein the raw materials of the transparent flame-retardant epoxy resin material include DOPO derivatives shown in Formula I.

[0036] Furthermore, in the flame-retardant epoxy resin material, the amount of the DOPO derivative shown in Formula I added is 1 to 10 wt% of the flame-retardant epoxy resin material; preferably 1 to 5 wt%.

[0037] The beneficial effects of this invention are:

[0038] 1. The novel DOPO derivative with a benzozazaporium structure obtained by this invention has the advantage of achieving high flame retardant performance with low addition amount when used as a flame retardant. Only 4%wt of addition amount can achieve a limiting oxygen index of ≥38% for epoxy resin flame retardant materials and pass the UL94V-0 level; and transparent flame retardant epoxy resin materials can be obtained.

[0039] 2. The DOPO raw material used in the novel DOPO-derived flame retardant DBDs containing benzo[a]azapyridine obtained by this invention is itself an excellent organophosphorus flame retardant that can react with a wide variety of phosphorus-containing compounds. At the same time, the introduction of phosphonate ester structure enables the product to obtain good flame retardancy while increasing the thermal stability of the substrate.

[0040] 3. The preparation method of the novel DOPO-derived flame retardant DBDs containing benzozazaporium obtained by the present invention has a high yield of 85-95%, and the raw materials are cheap and readily available. The post-processing operation is simple, easy to operate, low in cost, and easy to scale up and produce; it has good prospects for industrial application. Attached Figure Description

[0041] To further illustrate the product's structure and performance, R 1 R 2 Taking the novel DOPO-derived flame retardants DBDS and DBDO flame retardants, both of which contain hydrogen and sulfur and oxygen respectively, as examples, the following figures are provided.

[0042] Figure 1 Infrared spectrum of DBDS flame retardant (Example 1); Figure 1 This indicates that 3296cm -1 The peak represents the stretching vibration of the NH bond, at 3061 cm⁻¹. -1 This is the stretching vibration peak of the CH bond on the benzene ring, at 2857 cm⁻¹. -1 The peak represents the bending vibration of the methylene CH bond, at 1230 cm⁻¹. -1 The peak represents the stretching vibration of the O=P bond, at 1118 cm⁻¹. -1 The stretching vibration is O=PC, 927cm -1 The absorption peak for the POC bond is at 1476 cm⁻¹. -1 The absorption peak for P-Ph is at 1591 cm⁻¹. -1 The peak at 2436 cm⁻¹ represents the absorption peak of the benzene ring. In this spectrum, DBDS shows an absorption peak at 2436 cm⁻¹. -1 The disappearance of the pH bond, 3296cm -1 The presence of NH bonds, and simultaneously the peak of O=P bonds from 1240 cm⁻¹ -1 It becomes 1230cm -1 This allows for a preliminary assessment of the successful synthesis of the flame retardant DBDS.

[0043] Figure 2 Infrared spectrum of DBDO flame retardant (Example 2); Figure 2 This indicates that 3287cm -1 The peak represents the stretching vibration of the NH bond, at 3061 cm⁻¹. -1 This is the stretching vibration peak of the CH bond on the benzene ring, 1225 cm⁻¹. -1The peak represents the stretching vibration of the O=P bond, at 1118 cm⁻¹. -1 The stretching vibration is O=PC, 922cm -1 The absorption peak for the POC bond is 1503 cm⁻¹. -1 The absorption peak for P-Ph is at 1608 cm⁻¹. -1 The peak at 2436 cm⁻¹ represents the absorption peak of the benzene ring. In this spectrum, DBDO shows an absorption peak at 2436 cm⁻¹. -1 The disappearance of the pH bond, 3287cm -1 The presence of NH bonds, and simultaneously the peak of O=P bonds from 1240 cm⁻¹ -1 It became 1225cm -1 This allows for a preliminary assessment of the successful synthesis of the flame retardant DBDO.

[0044] Figure 3 and Figure 4 The NMR spectrum of DBDS flame retardant (Example 1); Figure 3 and Figure 4 This indicates that, using deuterated chloroform as a solvent, the peak at δ7.26 is the H peak of the deuterated chloroform solvent, δ6.95-7.30 is the Ar-H peak on the benzene ring, δ7.32-7.84 is the Ar-H peak on the (Ph)2-P=O benzene ring, δ6.02-6.65 is the NH peak, and δ3.73 is the H peak of the methylene group of O=PO-CH2; Figure 4 This indicates that δ31.55 and 30.79 are absorption peaks of phosphorus atoms on (Ph)2-P=O.

[0045] Figure 5 and Figure 6 The NMR spectrum of DBDO flame retardant (Example 2); Figure 5 and Figure 6 This indicates that, using deuterated chloroform as a solvent, the peak at δ7.26 is the H peak of the deuterated chloroform solvent, the peak at δ6.80-7.26 is the Ar-H peak on the benzene ring, the peak at δ7.57-7.71 is the Ar-H peak on the (Ph)2-P=O benzene ring, the peak at δ6.44-6.64 is the NH peak, and the peak at δ4.89 is the H peak of the methylene group of O=PO-CH2; Figure 6 This indicates that δ31.46 is the absorption peak of phosphorus atoms on (Ph)2-P=O. Detailed Implementation

[0046] Benzoazapyrrolidones are a class of nitrogen-containing seven-membered heterocyclic benzo[a]-fused-ring compounds with unique structural rigidity and biological activity. This invention provides a novel DOPO-derived flame retardant containing benzoazapyrrolidones—6-(10,11-dihydrodibenzo[b,f][1,4]azapyrrolidone-11-yl)dibenzo[c,e][1,2]oxa-phosphaphenanthrene-6-oxide (DBDs). The resulting novel DOPO derivative containing benzoazapyrrolidones can not only serve as an intermediate in organic synthesis, but also, due to its excellent thermal stability and abundance of flame-retardant elements, is particularly suitable as a polymeric flame retardant. When used as an additive flame retardant for epoxy resins, an addition of only 4% wt can achieve a limiting oxygen index ≥38% for the epoxy resin flame-retardant material, and pass the UL94V-0 level; furthermore, the resulting flame-retardant epoxy resin is a transparent material.

[0047] The specific embodiments of the present invention will be further described below with reference to examples, but the present invention is not limited to the scope of the examples described.

[0048] Example 1

[0049] In a 250 mL round-bottom flask equipped with a stir bar, o-mercaptoaniline (0.1 mol, 12.50 g), o-fluorobenzaldehyde (0.1 mol, 12.40 g), and potassium carbonate (0.15 mol, 20.70 g) were added, followed by 80 mL of the organic solvent N,N-dimethylformyl (DMF). After stirring at room temperature until homogeneous, the mixture was transferred to an oil bath at 150 °C and reacted for 4 h. After the reaction was complete, the mixture was washed with DMF and filtered to obtain a white powder. The filter residue was then miscible with H₂O and dichloromethane (DCM) to extract the lower organic phase. Finally, the obtained organic phase was rotary evaporated to remove DCM, and the solid obtained after drying was the benzo[a]azapyrrolizidine compound.

[0050] The obtained solid (0.1 mol, 21.1 g) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO 0.1 mol, 21.60 g) were then added to a 250 mL round-bottom flask containing a stir bar, followed by 60 mL of ethanol. After stirring thoroughly at room temperature, the mixture was transferred to an oil bath at 80 °C and refluxed for 6 h. After the reaction was complete, the mixture was washed with anhydrous ethanol and filtered to obtain DBDS as the residue, with a yield of 93%.

[0051] Example 2

[0052] In a 250 mL round-bottom flask equipped with a stir bar, o-hydroxyaniline (0.1 mol, 10.90 g), o-fluorobenzaldehyde (0.1 mol, 12.40 g), and potassium carbonate (0.15 mol, 20.70 g) were added, followed by 80 mL of the organic solvent N,N-dimethylformyl (DMF). After stirring thoroughly at room temperature, the mixture was transferred to an oil bath at 150 °C and reacted for 4 h. After the reaction was complete, the mixture was first miscible with H₂O and dichloromethane (DCM) to extract the lower organic phase. The DCM was then removed by rotary evaporation, and the solid was dried to obtain the final product.

[0053] Next, 0.1 mol (19.5 g) of solid and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO 0.1 mol, 21.60 g) were added to a 250 mL round-bottom flask containing a stir bar, followed by 60 mL of ethanol. After stirring thoroughly at room temperature, the mixture was transferred to an oil bath at 80 °C and reacted for 6 h. After the reaction was complete, the mixture was washed with anhydrous ethanol and filtered to obtain the residue DBDO, with a yield of 90%.

[0054] Example 3

[0055] In a 250 mL round-bottom flask equipped with a stir bar, o-aminoaniline (0.1 mol, 10.80 g), o-fluorobenzaldehyde (0.1 mol, 12.40 g), and potassium carbonate (0.15 mol, 20.70 g) were added, followed by 80 mL of the organic solvent N,N-dimethylformyl (DMF). After stirring at room temperature until homogeneous, the mixture was transferred to an oil bath at 150 °C and reacted for 4 h. After the reaction was complete, the mixture was washed with petroleum ether and filtered to obtain a white powder. The filter residue was then miscible with H₂O and dichloromethane (DCM) to extract the lower organic phase. Finally, the obtained organic phase was rotary evaporated to remove the DCM, and dried to obtain a solid.

[0056] The obtained solid (0.1 mol, 19.50 g) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO 0.1 mol, 21.60 g) were then added to a 250 mL round-bottom flask containing a stir bar, followed by 60 mL of ethanol. After stirring thoroughly at room temperature, the mixture was transferred to an oil bath at 80 °C and reacted for 6 h. After the reaction was complete, the mixture was washed with anhydrous ethanol and filtered to obtain the product, with a yield of 85%.

[0057] Example 4

[0058] In a 250 mL round-bottom flask equipped with a stir bar, o-hydroxyaniline (0.1 mol, 10.90 g), o-chlorobenzaldehyde (0.1 mol, 140 g), and potassium carbonate (0.15 mol, 20.70 g) were added, followed by 80 mL of the organic solvent N,N-dimethylformyl (DMF). After stirring thoroughly at room temperature, the mixture was transferred to an oil bath at 150 °C and reacted for 4 h. After the reaction was complete, the mixture was first miscible with H₂O and dichloromethane (DCM), and the lower organic phase was extracted. The DCM was then removed by rotary evaporation, and the solid was dried to obtain the final product.

[0059] The obtained solid (0.1 mol, 19.50 g) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO 0.1 mol, 21.60 g) were then added to a 250 mL round-bottom flask containing a stir bar, followed by 60 mL of ethanol. After stirring thoroughly at room temperature, the mixture was transferred to an oil bath at 80 °C and reacted for 6 h. After the reaction was complete, the mixture was washed with anhydrous ethanol and filtered to obtain the product DBDO in 95% yield.

[0060] Example 5

[0061] In a 250 mL round-bottom flask equipped with a stir bar, 0.1 mol (12.50 g) of 2,4-dihydroxyaniline, 0.1 mol (12.40 g) of o-fluorobenzaldehyde, and 0.15 mol (6.00 g) of sodium hydroxide were added, followed by 80 mL of N,N-dimethylformyl (DMF) organic solvent. After stirring at room temperature until homogeneous, the mixture was transferred to an oil bath at 150 °C and reacted for 4 h. After the reaction was complete, the mixture was washed with petroleum ether and filtered to obtain a white powder. The filter residue was then miscible with H₂O and dichloromethane (DCM) to extract the lower organic phase. Finally, the obtained organic phase was rotary evaporated at 45 °C to remove DCM, and dried to obtain a solid.

[0062] Next, 0.1 mol (21.10 g) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO 0.1 mol, 21.60 g) were added to a 250 mL round-bottom flask containing a stir bar, followed by 60 mL of ethanol. After stirring thoroughly at room temperature, the mixture was transferred to an oil bath at 80 °C and reacted for 6 h. After the reaction was complete, the mixture was washed with anhydrous ethanol and filtered to obtain the product, with a yield of 91%.

[0063] Example 6

[0064] In a 250 mL round-bottom flask equipped with a stir bar, o-hydroxyaniline (0.1 mol, 10.90 g), 4-amino-o-fluorobenzaldehyde (0.1 mol, 13.90 g), and potassium carbonate (0.15 mol, 20.70 g) were added, followed by 80 mL of the organic solvent chlorobenzene (PhCl). After stirring thoroughly at room temperature, the mixture was transferred to an oil bath at 150 °C and reacted for 4 h. After the reaction was complete, the mixture was first miscible with H₂O and dichloromethane (DCM), and the lower organic phase was extracted. The DCM was then removed by rotary evaporation, and the solid was dried to obtain the final product.

[0065] The obtained solid (0.1 mol, 21.00 g) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO 0.1 mol, 21.60 g) were then added to a 250 mL round-bottom flask containing a stir bar, followed by 60 mL of ethanol. After stirring thoroughly at room temperature, the mixture was transferred to an oil bath at 80 °C and reacted for 6 h. After the reaction was complete, the mixture was washed with anhydrous ethanol and filtered to obtain the residue product, with a yield of 86%.

[0066] Example 7

[0067] In a 250 mL round-bottom flask equipped with a stir bar, o-hydroxyaniline (0.1 mol, 10.90 g), 4-phenyl-2-fluorobenzaldehyde (0.1 mol, 20.00 g), and triethylamine (0.15 mol, 15 g) were added, followed by 80 mL of anisole. After stirring thoroughly at room temperature, the mixture was transferred to an oil bath at 150 °C and reacted for 4 h. After the reaction was complete, the mixture was washed with petroleum ether and filtered to obtain a white powder. The filter residue was then miscible with H₂O and dichloromethane (DCM) to extract the lower organic phase. Finally, the obtained organic phase was rotary evaporated at 45 °C to remove the DCM, and dried to obtain a solid.

[0068] The obtained solid (0.1 mol, 27.10 g) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO 0.1 mol, 21.60 g) were then added to a 250 mL round-bottom flask containing a stir bar, followed by 60 mL of ethanol. After stirring thoroughly at room temperature, the mixture was transferred to an oil bath at 80 °C and reacted for 6 h. After the reaction was complete, the mixture was washed with anhydrous ethanol and filtered to obtain the product, with a yield of 91%.

[0069] Table 1. Structure and yield of some raw materials and products from Examples 1-7

[0070]

[0071] Preparation of epoxy resin: Preparation of pure specimens by vertical combustion

[0072] First, mechanically stir 48.00g of DGEBA in a 90℃ oil bath for 30 minutes. Then, add 12.00g of curing agent DDM to the mixture and mechanically stir for 5 minutes. While still hot, pour the mixture into a preheated stainless steel mold (130*13*3.2mm). 3 In the process, the film is fixed and placed in a forced-air oven to cure at 100℃ for 2 hours, and then the temperature is raised to 150℃ to cure for another 2 hours to obtain a flame-retardant epoxy resin cured product; named Neat EP.

[0073] Application Example 1

[0074] First, 2.40g of flame retardant DBDS from Example 1 and 46.08g of DGEBA were mechanically stirred in a 90°C oil bath for 30 minutes to obtain a white, homogeneous mixture. Then, 11.52g of curing agent DDM was added to the mixture and mechanically stirred for 5 minutes. While still hot, the mixture was poured into a preheated stainless steel mold (130*13*3.2mm). 3 In the process of applying the film and fixing it, the product is placed in a forced-air oven and cured at 100℃ for 2 hours, then the temperature is raised to 150℃ and cured for another 2 hours to obtain a transparent flame-retardant epoxy resin cured product; named EP / DBDS. 4％ .

[0075] Application Example 2

[0076] First, 1.60g of flame retardant DBDO from Example 2 and 30.72g of DGEBA were mechanically stirred in a 90°C oil bath for 30 minutes to obtain a white, homogeneous mixture. Then, 7.68g of curing agent DDM was added to the mixture and mechanically stirred for 5 minutes. While still hot, the mixture was poured into a preheated stainless steel mold (130*13*3.2mm). 3 In the process of applying and fixing the film, place it in a forced-air oven at 100℃ for 2 hours to cure, and then raise the temperature to 150℃ for another 2 hours to obtain a transparent flame-retardant epoxy resin cured product. This product is named EP / DBDO. 4％ .

[0077] Flame retardancy test

[0078] The limiting oxygen index of the obtained flame-retardant materials was tested according to GB / T2406.2-2009 "Test Method for Burning Performance of Plastics - Oxygen Index Method"; the results are shown in Table 2.

[0079] Table 2 Flame Retardant Performance Table

[0080] Neat EP 0 26 NR <![CDATA[EP / DBDS 4％ ]]> 0.29 38±0.5 V-0 <![CDATA[EP / DBDO 4％ ]]> 0.30 37±0.5 V-0

[0081] Note: NR stands for stepless.

[0082] The above results indicate that without the addition of flame retardants, the limiting oxygen index (LOI) of epoxy resin is only about 26%, and its UL-94 rating is V-0. However, Table 2 shows that adding 4 wt% DBDS can increase the LIO of epoxy resin to 38% with a phosphorus content of 0.29%, and the UL-94 rating is V-0. Simultaneously, adding 4 wt% DBDO can increase the LIO of epoxy resin to 37% with a phosphorus content of 0.30%, and the UL-94 rating is V-0. Furthermore, the resulting epoxy resin materials containing benzozazepine DOPO-derived flame retardants are all transparent. This demonstrates that the prepared flame retardants can impart excellent flame retardant properties and processability to epoxy resins at low phosphorus contents (≤0.5%).

[0083] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions conceived without inventive effort should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A DOPO derivative containing benzozazepine, characterized in that, The general structural formula of the DOPO derivative containing benzo[a]azine is shown in Formula I: Formula I In formula I, R 1 R 2 X represents hydrogen, amino, hydroxyl, or phenyl; X represents N, O, or S.

2. The DOPO derivative containing benzozazepine according to claim 1, characterized in that, The structural formula of the DOPO derivative containing benzo[a]azine is as follows: , , , or ; Where X = N, O, or S.

3. The method for preparing a DOPO derivative containing benzozazepine according to claim 1, characterized in that, The preparation method is as follows: A benzozapazole compound, a DOPO compound, and an organic solvent are added to a reaction vessel, stirred evenly at room temperature, and then refluxed at 60–150°C for 2–12 h. After the reaction is completed, the mixture is filtered and dried to obtain the DOPO derivative containing benzozapazole. The benzozapazole compound is prepared by the following method: [The text abruptly ends here, so the translation stops.] aniline, with the structural formula as follows o-Hydrobenzaldehyde, alkali and organic solvents, at 0-25 o Stir well under temperature C, then at 40-200°C. o The reaction proceeds for 2–10 h at step C; after the reaction is complete, the benzo[a]azapyridine compound is obtained by washing, filtering, purifying, and drying; wherein, Z = OH, SH, or NH2, Y = F, Cl, Br, or I; R 1 R 2 It can be hydrogen, amino, hydroxyl, or phenyl.

4. The method for preparing a DOPO derivative containing benzozazepine according to claim 3, characterized in that, The mass ratio of the benzozazepine compound to the DOPO compound is 1:0.7–2; and / or: The organic solvent includes alcohol solvents, ether solvents, sulfone solvents, or aromatic solvents; and / or: The volume ratio of the organic solvent added to the DOPO compound is 1-4 mL: 1 g.

5. The method for preparing a DOPO derivative containing benzozazepine according to claim 3, characterized in that, The organic solvent is selected from: methanol, ethanol, anisole, diethyl ether, 1,4-dioxane, dimethyl sulfoxide, toluene, benzene, dichloromethane, chloroform, xylene, pyridine, chlorobenzene, acetonitrile, propionitrile, N,N-dimethylformamide, and N,N-dimethylacetamide.

6. The method for preparing a DOPO derivative containing benzozazepine according to claim 5, characterized in that, The organic solvent is selected from pyridine, anisole, chlorobenzene, and N,N-dimethylformamide.

7. The method for preparing a DOPO derivative containing benzozazepine according to claim 3, characterized in that, The structural formula is: The substances shown are selected from: 2-hydroxyaniline, 2-mercaptoaniline, or 2-aminoaniline; and / or: The structural formula is: The o-halobenzaldehyde shown is selected from o-fluorobenzaldehyde and o-chlorobenzaldehyde.

8. The method for preparing a DOPO derivative containing benzozazepine according to claim 3, characterized in that, The base includes: sodium methoxide, triethylamine, pyridine, sodium ethoxide, potassium tert-butoxide, sodium tert-butoxide, potassium bis(trimethylsilyl)amino, lithium bis(trimethylsilyl)amino, sodium bis(trimethylsilyl)amino, lithium tert-butyllithium, sodium hydride, sodium hydroxide, potassium hydroxide, and cesium carbonate.

9. Use of a DOPO derivative containing benzozazepine as described in claim 1 or 2 as a flame retardant.

10. The use according to claim 9, characterized in that, The DOPO derivatives containing benzozazepines are used as flame retardants in epoxy resins, polyurethanes, polyesters, or polyamides.

11. A flame-retardant epoxy resin material, characterized in that, The raw materials for the flame-retardant epoxy resin material include the DOPO derivative containing benzo[a]azine as described in claim 1 or 2.

12. The flame-retardant epoxy resin material according to claim 11, characterized in that, The raw materials and their proportions for the flame-retardant epoxy resin material are as follows: 30-48 parts by weight of bisphenol A diglycidyl ether, 5-14 parts by weight of diaminodiphenylmethane, and 1-4 parts by weight of DOPO derivatives containing benzodiazepines. When the amount of DOPO derivative containing benzo[a]azine is 4 wt%, the limiting oxygen index of the flame-retardant epoxy resin material is 38%.

13. The flame-retardant epoxy resin material according to claim 11, characterized in that, The amount of the DOPO derivative containing benzodiazepine added is 1 to 5 wt% of the flame-retardant epoxy resin material.

14. A transparent flame-retardant epoxy resin material, characterized in that, The raw materials for the transparent flame-retardant epoxy resin material include the DOPO derivative containing benzo[a]azine as described in claim 1 or 2.

15. A transparent flame-retardant epoxy resin material according to claim 14, characterized in that, In the transparent flame-retardant epoxy resin material, the amount of DOPO derivative containing benzo[a]azine is 1 to 10 wt% of the transparent flame-retardant epoxy resin material.

16. The transparent flame-retardant epoxy resin material according to claim 15, characterized in that, The amount of DOPO derivatives containing benzodiazepines added is 1 to 5 wt% of the transparent flame-retardant epoxy resin material.

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