A method of synthesizing 4,4',4"-triaminotriphenylmethane

Abstract

The application provides a method for synthesizing triaminotriphenylmethane, which does not need to use a solvent, uses N,N'-dibenzylaniline and trialkoxymethane as synthetic raw materials, and makes N,N'-dibenzylaniline and trialkoxymethane undergo a Friedel-Crafts alkylation reaction, so as to avoid the generation of 2,4',4"-triaminotriphenylmethane isomers in a traditional synthesis method by using the steric effect of two benzyl protective groups, thereby obtaining 4,4',4"-tri(N,N'-dibenzylaminophenyl)methane with high selectivity. 4,4',4"-tri(N,N'-dibenzylaminophenyl)methane is further subjected to a debenzylation reaction under neutral conditions to form triaminotriphenylmethane. According to the chemical structural formula of the target product, the benzyl group as the protective group of the amino group is reduced under a neutral environment, and the benzyl group is removed, and the formed byproduct is only toluene, which not only ensures the high yield and high selectivity of the target product, but also is very beneficial to obtaining high-purity 4,4',4"-triaminotriphenylmethane, and conforms to the principle of green chemistry.

Description

Technical Field

[0001] This invention relates to the fields of chemical manufacturing equipment and carbon materials technology, and in particular to a method for synthesizing 4,4',4”-triaminotriphenylmethane. Background Technology

[0002] 4,4',4”-Triaminotriphenylmethane (CAS No. 548-61-8) is an important chemical raw material, crucial for the preparation of high-performance adhesives such as Desmod (or Lechner adhesive) and numerous dyes. The chemical materials industry chain using 4,4',4”-Triaminotriphenylmethane (paracinon) as a raw material has a long history. However, the synthesis of this product has consistently presented challenges for both industry and academia, especially given today's emphasis on environmental protection.

[0003] The main reason for this is the low efficiency of triphenylmethane skeleton construction, resulting in the formation of the 2,4',4”-triaminotriphenylmethane isomer. This not only reduces the yield of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane but also makes separation difficult. Furthermore, the formation of 4,4',4”-triaminotriphenylmethane generates other impurities, such as products and polymers from the reaction of amino groups with aldehydes to form imines, posing significant challenges to its separation and purification, generating large amounts of wastewater, and ultimately leading to environmental non-compliance and production shutdowns.

[0004] Therefore, there is an urgent need to develop a mild, efficient, and highly selective green synthesis method to help achieve the engineered preparation of high-purity 4,4',4”-triaminotriphenylmethane and solve the problem that the original synthesis route does not meet environmental protection requirements. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a green, environmentally friendly, and efficient method for synthesizing 4,4',4”-triaminotriphenylmethane.

[0006] The specific details of the invention are as follows:

[0007] This invention provides a method for synthesizing 4,4',4”-triaminotriphenylmethane, the method comprising:

[0008] Step 1: In an acidic environment, N,N'-dibenzylaniline and trialkoxymethane in a molar ratio of 1:4-1:10 undergo a Friedel-Crafts alkylation reaction at 60-140 °C to prepare 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane;

[0009] Step 2: Mix the 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane with an appropriate amount of organic solvent, add a catalyst to the mixture and continuously pass hydrogen gas through it, or add an appropriate amount of hydrazine hydrate. The 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane undergoes a debenzylation reaction. After the reaction is complete, purify the mixture to obtain 4,4',4”-triaminotriphenylmethane.

[0010] Optionally, the trialkoxymethane is any one of trimethyl orthoformate, triethyl orthoformate, and tripropyl orthoformate;

[0011] The molar ratio of N,N'-dibenzylaniline to the trialkoxymethane is 1:6 to 1:8.

[0012] Optionally, in step 1, the Friedel-Crafts alkylation reaction is carried out at 80-120°C for 1-12 hours.

[0013] Optionally, in step 1, the acid used in the acidic conditions is any one of ferric chloride, aluminum chloride, boron trifluoride ether, ferric bromide, trifluoromethanesulfonic acid, bismuth trifluoromethanesulfonate, and bismuth nitrate.

[0014] Optionally, in step 2, the catalyst is palladium hydroxide / carbon or palladium / carbon.

[0015] Optionally, in step 2, the mass ratio of the catalyst to the 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane is 0.01:1-0.4:1.

[0016] Optionally, in step 2, the debenzylation reaction is carried out at room temperature to 100°C.

[0017] Optionally, in step 2, the mass ratio of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane to the organic solvent is 1:5-1:10;

[0018] The organic solvent is selected from at least one of toluene, methanol, ethanol, propanol, butanol, ethylene glycol, tetrahydrofuran, ethyl acetate, tert-butyl acetate, N,N-dimethylformamide, and water.

[0019] Optionally, in step 2, the pressure range of the hydrogen gas is 0.4-2 MPa.

[0020] Optionally, in step 2, the purification process includes: after the reaction is complete, distilling to remove excess solvent from the mixture to obtain a residue;

[0021] The residue is recrystallized or distilled under reduced pressure to obtain the triaminotriphenylmethane, wherein the purity of the 4,4',4”-triaminotriphenylmethane is not less than 95%.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] This invention provides a method for synthesizing 4,4',4”-triaminotriphenylmethane, using N,N'-dibenzylaniline and trialkoxymethane as raw materials. N,N'-dibenzylaniline and trialkoxymethane undergo a Friedel-Crafts alkylation reaction. Utilizing the steric hindrance effect of the two benzyl protecting groups, the formation of the 2,4',4”-triaminotriphenylmethane isomer is avoided in conventional synthesis methods, thus yielding 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane with high selectivity and high yield. Under neutral conditions, 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane further undergoes a debenzylation reaction to form triaminotriphenylmethane. Analysis of the chemical structure of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane reveals that the benzyl group, acting as a protecting group for the amino group, undergoes reduction under neutral conditions, removing the benzyl group. The only byproduct formed is toluene. This not only ensures high yield and high selectivity of the target compound but also greatly facilitates the acquisition of high-purity 4,4',4”-triaminotriphenylmethane. Furthermore, the byproduct toluene is easily recyclable without impacting the environment, exhibiting a very low environmental impact factor, which aligns with green chemistry.

[0024] Furthermore, in the process of obtaining 4,4',4”-tris(N,N'-dibenzylaniline)methane by Friedel-Crafts alkylation with N,N'-dibenzylaniline as a synthetic raw material, no solvent is required. Trialkoxymethane is used as both a reagent and a solvent, which improves the reaction efficiency and reduces the time spent on dissolution, thus conforming to the principles of green chemistry. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A flowchart of the method for synthesizing 4,4',4”-triaminotriphenylmethane provided in an embodiment of the present invention is shown;

[0027] Figure 2 The 1H NMR spectrum of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane provided in an embodiment of the present invention is shown.

[0028] Figure 3 The carbon NMR spectrum of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane provided in an embodiment of the present invention is shown.

[0029] Figure 4 The mass spectrum of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane provided in the embodiments of the present invention is shown.

[0030] Figure 5 The infrared spectrum of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane provided in an embodiment of the present invention is shown.

[0031] Figure 6 The 1H NMR spectrum of 4,4',4”-triaminotriphenylmethane provided in an embodiment of the present invention is shown.

[0032] Figure 7 The carbon NMR spectrum of 4,4',4”-triaminotriphenylmethane provided in an embodiment of the present invention is shown.

[0033] Figure 8 The infrared spectrum of 4,4',4”-triaminotriphenylmethane provided in an embodiment of the present invention is shown. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0035] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0036] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of this specification.

[0037] In the description of this invention, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0038] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] This invention provides a method for synthesizing 4,4',4”-triaminotriphenylmethane. Using N,N'-dibenzylaniline and trialkoxymethane as raw materials, N,N'-dibenzylaniline and trialkoxymethane undergo a Friedel-Crafts alkylation reaction to obtain 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane. Under neutral conditions, 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane further undergoes a debenzylation reaction to form triaminotriphenylmethane. The structural formula of N,N'-dibenzylaniline is shown in Formula III; the structural formula of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane is shown in Formula II; and the structural formula of 4,4',4”-triaminotriphenylmethane is shown in Formula I. The following provides a detailed analysis of the synthetic route for synthesizing 4,4',4”-triaminotriphenylmethane (Formula I) from N,N'-dibenzylaniline (Formula III).

[0040]

[0041] Figure 1 A flowchart of the method for synthesizing 4,4',4”-triaminotriphenylmethane provided in an embodiment of the present invention is shown, as follows: Figure 1 As shown, the synthesis method includes:

[0042] S1: In an acidic environment, N,N'-dibenzylaniline of Formula III with a molar ratio of 1:4-1:10 undergoes a Friedel-Crafts alkylation reaction with trialkoxymethane at 60-140 °C to prepare 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane of Formula II;

[0043] In specific implementation, this step selects N,N'-dibenzylaniline as shown in Formula III and trialkoxymethane as the synthetic raw materials for Friedel-Crafts alkylation reaction. The alkoxy group in the trialkoxymethane is replaced by N,N'-dibenzylaniline as shown in Formula III (the linkage site is located on the para-benzene ring of aniline), generating the intermediate product 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane, while releasing an alkyl alcohol.

[0044] In this embodiment of the invention, N,N'-dibenzylaniline is used as a synthetic raw material. In the process of obtaining 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane by Friedel-Crafts alkylation with trialkoxymethane, no solvent is required. Trikoxymethane is used as both a reaction reagent and a solvent, which improves the reaction efficiency and reduces the time spent on dissolution, in line with the principles of green chemistry.

[0045] In some embodiments, the trialkoxymethane is any one of trimethyl orthoformate, triethyl orthoformate, and tripropyl orthoformate; the molar ratio of N,N'-dibenzylaniline to trialkoxymethane is 1:4-1:10, preferably 1:6-1:8; the Friedel-Crafts alkylation reaction is carried out in an acidic environment, the reaction temperature is controlled at 60-140°C, preferably 80-120°C, and the reaction time is 1-12 h.

[0046] S2: 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane is mixed with an appropriate amount of neutral organic solvent. A catalyst is added to the mixture, and hydrogen gas is continuously introduced, or an appropriate amount of hydrazine hydrate is added. The 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane undergoes a debenzylation reaction. After the reaction is complete, the mixture is purified to obtain 4,4',4”-triaminotriphenylmethane as shown in Formula I.

[0047] In practice, this step utilizes reducing hydrogen or hydrazine hydrate to catalyze the hydrogenation of the intermediate 4,4',4"-tris(N,N'-dibenzylaminophenyl)methane, causing the benzyl group in 4,4',4"-tris(N,N'-dibenzylaminophenyl)methane to be replaced by hydrogen (debenzylation). During this process, the benzyl group, acting as a protecting group for the amino group, is removed under neutral conditions, transforming the product into 4,4',4"-triaminotriphenylmethane.

[0048] In some embodiments, the catalyst used for debenzylation is palladium hydroxide / carbon or palladium / carbon, and the mass ratio of the catalyst to 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane is 0.01:1-0.4:1. It should be noted that palladium hydroxide / carbon (3%-10%) refers to the mass ratio of palladium hydroxide to the total mass ratio of the palladium hydroxide / carbon catalyst being 3%-10%; palladium / carbon (3%-10%) refers to the mass ratio of palladium to the total mass ratio of the palladium / carbon catalyst being 3%-10%.

[0049] In some embodiments, the neutral organic solvent is selected from at least one of toluene, methanol, ethanol, propanol, butanol, ethylene glycol, tetrahydrofuran, ethyl acetate, tert-butyl acetate, N,N-dimethylformamide, and water, and the mass ratio of tris(N,N'-dibenzylaminophenyl)methane to the neutral organic solvent is 1:5 to 1:10.

[0050] In the above synthetic route, the synthesis of the intermediate 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane is a key consideration. This invention addresses this by introducing benzyl and methyl groups into the aniline molecule to form 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane, using the benzyl group as a protecting group for the amino group, and further converting it into an amino compound under neutral conditions. Thus, the only byproduct is toluene, resulting in a high conversion rate and high selectivity in the synthesis of the target compound (4,4',4”-triaminotriphenylmethane), ensuring the purity of the target compound, avoiding cumbersome purification processes, and reducing environmental pollution.

[0051] In some embodiments, 4,4',4”-triaminotriphenylmethane with a purity of not less than 95% can be obtained after purification. Specific methods include: after the reaction is complete, distilling to remove excess solvent from the mixed system to obtain a residue; recrystallizing or vacuum distilling the residue to obtain 4,4',4”-triaminotriphenylmethane.

[0052] To enable those skilled in the art to more clearly understand the present invention, a method for synthesizing 4,4',4”-triaminotriphenylmethane according to the present invention will now be described in detail through the following examples.

[0053] This invention provides an efficient synthetic method for 4,4',4”-triaminotriphenylmethane, as shown in structural formula I. The synthetic route is as follows:

[0054]

[0055] Using N,N'-dibenzylaniline (structure III) as a raw material, it undergoes a Friedel-Crafts alkylation reaction with one of trimethyl orthoformate, triethyl orthoformate, or tripropyl orthoformate to obtain 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane (structure II), which is then debenzylated to obtain 4,4',4”-triaminotriphenylmethane (structure I).

[0056] Example 1

[0057] (1) Preparation of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane

[0058] N,N'-dibenzylaniline (21.87 g, 80 mmol) was added to a 250 mL three-necked flask, purged three times with argon gas, and then excess trimethyl orthoformate (100 mL) and boron trifluoride diethyl ether (3.41 g) were added. The mixture was heated to reflux at 100 °C for 3 h. The reaction of the starting material N,N'-dibenzylaniline was confirmed by TLC to be complete, and heating was stopped. After cooling to room temperature, boron trifluoride diethyl ether and trimethyl orthoformate were removed by rotary evaporation. The resulting solid was recrystallized from methanol to give 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane, which was used in the next reaction (19.92 g, 24 mmol, 90% yield), with a melting point of 69-71 °C.

[0059] Figure 2 The 1H NMR spectrum of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane provided in an embodiment of the present invention is shown below:

[0060] 1 H NMR (400MHz, DMSO-d6) δ (ppm): 7.27-7.18 (m, 30H), 6.73 (d, J = 8.0Hz, 6H), 6.51 (d, J = 8.0Hz, 6H), 4.97 (s, 1H), 4.57 (s, 12H).

[0061] like Figure 2 As shown, the 1H NMR spectrum only shows the peak of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane, with no other product peaks. That is, all six benzyl groups have been removed; there are no compounds with one or two remaining benzyl groups. Furthermore, the 1H NMR spectrum also does not show peaks for products that have undergone excessive hydrogenation (such as further hydrogenation of the benzene ring to cyclohexane), thus demonstrating high selectivity.

[0062] Figure 3 The carbon NMR spectrum of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane provided in the embodiments of the present invention is shown below:

[0063] 13 C NMR (100MHz, CDCl3) δ (ppm): 147.41, 139.02, 133.60, 130.02, 128.68, 126.88, 126.80, 112.16, 54.34, 54.19.

[0064] Figure 4 The mass spectrum of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane provided in the embodiments of the present invention is shown below:

[0065] HR-MS: m / z 830.4467(C 61 H 55 N3 required (830.13)

[0066] Figure 5 The infrared spectrum of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane provided in an embodiment of the present invention is shown below:

[0067] FT-IR (cm) -1 ):3025(w),2910(w),2860(w),1608(m).

[0068] (2) Synthesis of triaminotriphenylmethane

[0069] 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane (3.22 g, 4 mmol), 5% Pd / C catalyst (0.2 mmol, 425.7 mg), and methanol (10 ml) were added to a high-pressure reactor. The reactor was evacuated, and argon gas was introduced. This process was repeated three times to replace the argon atmosphere. The reactor was then purged with hydrogen gas and heated at 60 °C with stirring at 1 MPa. The reaction was monitored by TLC until complete. The Pd / C catalyst was filtered, and the filtrate was rotary evaporated to obtain pure 4,4',4”-triaminotriphenylmethane (1.10 g, 3.8 mmol, 95% yield) with a melting point of 198-200 °C.

[0070] Figure 6 The 1H NMR spectrum of 4,4',4”-triaminotriphenylmethane provided in an embodiment of the present invention is shown below:

[0071] 1 H NMR (400MHz, DMSO-d6) δ (ppm): 6.70 (d, J = 8.0 Hz, 6H), 6.45 (d, J = 8.0 Hz, 6H), 4.98 (s, 1H), 4.83 (s, 6H).

[0072] Figure 7 The carbon NMR spectrum of 4,4',4”-triaminotriphenylmethane provided in an embodiment of the present invention is shown below:

[0073] APT- 13 C NMR (100MHz, DMSO-d6) δ (ppm): 146.74, 133.36, 129.72, 114.08, 54.37.

[0074] Figure 8 The infrared spectrum of 4,4',4”-triaminotriphenylmethane provided in an embodiment of the present invention is shown.

[0075] FT-IR (cm) -1 ): 3608(w), 3333(m), 1610(s).

[0076] Example 2:

[0077] The implementation content of this embodiment is similar to that of Embodiment 1 above, except that: the catalyst used for catalyzing the Friedel-Crafts alkylation reaction is bismuth trifluoromethanesulfonate, and the solvent used for catalyzing the hydrogenation debenzylation is toluene.

[0078] (1) Preparation of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane

[0079] N,N'-dibenzylaniline (21.87 g, 80 mmol) was added to a 250 mL three-necked flask, purged three times with argon gas, and then excess trimethyl orthoformate (100 mL) and bismuth trifluoromethanesulfonate (15.75 g) were added. The mixture was heated to reflux at 100 °C for 3 h. The reaction of the starting material N,N'-dibenzylaniline was confirmed by TLC to be complete, and heating was stopped. After cooling to room temperature, the bismuth trifluoromethanesulfonate was filtered off, and excess trimethyl orthoformate was removed by rotary evaporation. The resulting solid was recrystallized from methanol to give 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane, which was used in the next reaction (19.48 g, 23 mmol, yield 88%).

[0080] (2) Synthesis of 4,4',4”-triaminotriphenylmethane

[0081] 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane (3.22 g, 4 mmol), 5% Pd / C catalyst (0.2 mmol, 425.7 mg), and 10 ml of toluene were added to a high-pressure reactor. The reactor was evacuated, and argon gas was introduced. This process was repeated three times to replace the argon atmosphere. The reactor was then purged with hydrogen gas and heated at 60 °C with stirring at 1 MPa. The reaction was monitored by TLC until complete. The Pd / C catalyst was filtered, and the filtrate was rotary evaporated to obtain pure 4,4',4”-triaminotriphenylmethane (1.10 g, 3.8 mmol, 95% yield).

[0082] The carbon NMR spectrum, hydrogen NMR spectrum, mass spectrum, and infrared spectrum of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane obtained in this embodiment are the same as those in Example 1. They will not be shown again here.

[0083] The NMR carbon spectrum, NMR hydrogen spectrum, and infrared spectrum of 4,4',4”-triaminotriphenylmethane obtained in this embodiment are the same as those in Example 1, proving that 4,4',4”-triaminotriphenylmethane was successfully synthesized in this embodiment, and will not be shown again here.

[0084] Example 3

[0085] The implementation content of this embodiment is similar to that of Embodiment 1 above, except that: the Friedel-Crafts alkylating agent used is triethyl orthoformate, the catalyst is ferric chloride, the solvent used for catalytic hydrogenation debenzylation is ethyl acetate, and the catalyst is 10% Pd(OH)2 / C.

[0086] (1) Preparation of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane

[0087] N,N'-dibenzylaniline (21.87 g, 80 mmol) was added to a 250 mL three-necked flask, purged three times with argon gas, and then excess triethyl orthoformate (100 mL) and ferric chloride (3.41 g) were added. The mixture was heated to reflux at 100 °C for 3 h. The reaction of the starting material N,N'-dibenzylaniline was confirmed by TLC to be complete, and heating was stopped. After cooling to room temperature, ferric chloride was removed by filtration, and triethyl orthoformate was removed by rotary evaporation. The resulting solid was recrystallized from methanol to give 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane, which was used in the next reaction (20.15 g, 25 mmol, yield 91%).

[0088] (2) Synthesis of 4,4',4”-triaminotriphenylmethane

[0089] 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane (3.22 g, 4 mmol), 10% Pd(OH)₂ / C catalyst (0.2 mmol, 280.86 mg), and 10 mL of ethyl acetate were added to a high-pressure reactor. The reactor was evacuated and purged with argon gas three times, replacing the argon atmosphere. The reactor was then purged with hydrogen gas and heated at 60 °C with stirring at 1 MPa. The reaction was monitored by TLC until complete. The Pd(OH)₂ / C catalyst was filtered, and the filtrate was rotary evaporated to obtain relatively pure 4,4',4”-triaminotriphenylmethane (1.11 g, 3.84 mmol, yield 96%).

[0090] The carbon NMR spectrum, hydrogen NMR spectrum, mass spectrum, and infrared spectrum of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane obtained in this embodiment are the same as those in Example 1. They will not be shown again here.

[0091] The NMR carbon spectrum, NMR hydrogen spectrum, and infrared spectrum of 4,4',4”-triaminotriphenylmethane obtained in this embodiment are the same as those in Example 1, proving that 4,4',4”-triaminotriphenylmethane was successfully synthesized in this embodiment, and will not be shown again here.

[0092] Example 4

[0093] The implementation content of this embodiment is similar to that of Embodiment 1 above, except that: the Friedel-Crafts alkylating agent used is tripropyl orthoformate, the catalyst used is aluminum trichloride, and the solvent used for catalytic hydrogenation debenzylation is tetrahydrofuran.

[0094] (1) Preparation of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane

[0095] N,N'-dibenzylaniline (21.87 g, 80 mmol) was added to a 250 mL three-necked flask, purged three times with argon gas, and then excess tripropyl orthoformate (100 mL) and aluminum trichloride (3.41 g) were added. The mixture was heated to reflux at 100 °C for 3 h. The reaction of the starting material N,N'-dibenzylaniline was confirmed by TLC to be complete, and heating was stopped. After cooling to room temperature, aluminum trichloride was removed by filtration, and tripropyl orthoformate was removed by rotary evaporation. The resulting solid was recrystallized from methanol to give 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane, which was used in the next reaction (14.98 g, 23 mmol, yield 88%).

[0096] (2) Synthesis of 4,4',4”-triaminotriphenylmethane

[0097] 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane (3.22 g, 4 mmol), 5% Pd / C catalyst (0.2 mmol, 425.7 mg), and 10 ml tetrahydrofuran were added to a high-pressure reactor. The reactor was evacuated, and argon gas was introduced. This process was repeated three times to replace the argon atmosphere. The reactor was then purged with hydrogen gas and heated at 60 °C with stirring at 1 MPa. The reaction was monitored by TLC until complete. The Pd / C catalyst was filtered, and the filtrate was rotary evaporated to obtain relatively pure 4,4',4”-triaminotriphenylmethane (1.1 g, 3.8 mmol, 95% yield).

[0098] The carbon NMR spectrum, hydrogen NMR spectrum, mass spectrum, and infrared spectrum of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane obtained in this embodiment are the same as those in Example 1. They will not be shown again here.

[0099] The NMR carbon spectrum, NMR hydrogen spectrum, and infrared spectrum of 4,4',4”-triaminotriphenylmethane obtained in this embodiment are the same as those in Example 1, proving that 4,4',4”-triaminotriphenylmethane was successfully synthesized in this embodiment, and will not be shown again here.

[0100] Example 5

[0101] The implementation content of this embodiment is similar to that of Embodiment 1 above, except that the solvent used for catalytic hydrogenation debenzylation is N,N-dimethylformamide and the catalyst is 10% Pd / C.

[0102] (1) Preparation of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane

[0103] N,N'-dibenzylaniline (21.87 g, 80 mmol) was added to a 250 mL three-necked flask, purged three times with argon gas, and then excess trimethyl orthoformate (100 mL) and boron trifluoride diethyl ether (3.41 g) were added. The mixture was heated to reflux at 100 °C for 3 h. The reaction of the starting material N,N'-dibenzylaniline was confirmed by TLC to be complete, and heating was stopped. After cooling to room temperature, boron trifluoride diethyl ether and trimethyl orthoformate were removed by rotary evaporation. The resulting solid was recrystallized from methanol to give 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane, which was used in the next reaction (19.92 g, 24 mmol, 90% yield).

[0104] (2) Synthesis of 4,4',4”-triaminotriphenylmethane

[0105] 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane (3.22 g, 4 mmol), 10% Pd / C catalyst (0.2 mmol, 212.8 mg), and 10 ml N,N-dimethylformamide were added to a high-pressure reactor. The reactor was evacuated and purged with argon gas, repeated three times to replace the argon atmosphere. The reactor was then purged with hydrogen gas and heated at 60 °C with stirring at 1 MPa. The reaction was monitored by TLC until complete. The Pd / C catalyst was filtered, and the filtrate was rotary evaporated to obtain pure 4,4',4”-triaminotriphenylmethane (1.10 g, 3.8 mmol, 95% yield).

[0106] The carbon NMR spectrum, hydrogen NMR spectrum, mass spectrum, and infrared spectrum of 4,4',4”-tris(N,N'-dibenzylaminophenyl)methane obtained in this embodiment are the same as those in Example 1. They will not be shown again here.

[0107] The NMR carbon spectrum, NMR hydrogen spectrum, and infrared spectrum of 4,4',4”-triaminotriphenylmethane obtained in this embodiment are the same as those in Example 1, proving that 4,4',4”-triaminotriphenylmethane was successfully synthesized in this embodiment, and will not be shown again here.

[0108] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0109] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0110] The above provides a detailed description of a method for synthesizing 4,4',4”-triaminotriphenylmethane. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the invention. At the same time, those skilled in the art will recognize that, based on the ideas of the invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the invention.

Claims

1. A method for synthesizing triaminotriphenylmethane, characterized in that, The method includes: Step 1: In an acidic environment, N,N'-dibenzylaniline and trialkoxymethane in a molar ratio of 1:4-1:10 undergo a Friedel-Crafts alkylation reaction at 60-140 °C to prepare 4,4',4''-tris(N,N'-dibenzylaminophenyl)methane; Step 2: Mix the 4,4',4''-tris(N,N'-dibenzylaminophenyl)methane with an appropriate amount of neutral organic solvent, add a catalyst to the mixture and continuously pass hydrogen gas through it, or add an appropriate amount of hydrazine hydrate. The 4,4',4''-tris(N,N'-dibenzylaminophenyl)methane undergoes a debenzylation reaction. After the reaction is complete, remove the volatile components to obtain the 4,4',4''-triaminotriphenylmethane product. in: The trialkoxymethane is any one of trimethyl orthoformate, triethyl orthoformate, or tripropyl orthoformate. The acid used in the acidic conditions is any one of ferric chloride, aluminum chloride, boron trifluoride ether, ferric bromide, trifluoromethanesulfonic acid, bismuth trifluoromethanesulfonate, and bismuth nitrate. The catalyst is 3%-10% palladium hydroxide / carbon or 3%-10% palladium / carbon.

2. The method for synthesizing triaminotriphenylmethane according to claim 1, characterized in that, In step 1, the molar ratio of N,N'-dibenzylaniline to the trialkoxymethane is 1:6-1:

8.

3. The method for synthesizing triaminotriphenylmethane according to claim 1, characterized in that, In step 1, the Friedel-Crafts alkylation reaction is carried out at 80-120 °C for 1-12 h.

4. The method for synthesizing triaminotriphenylmethane according to claim 1, characterized in that, In step 2, the molar ratio of palladium to 4,4',4''-tris(N,N'-dibenzylaminophenyl)methane in the catalyst is 0.01:1-0.4:

1.

5. The method for synthesizing 4,4',4''-triaminotriphenylmethane according to claim 1, characterized in that, In step 2, the debenzylation reaction is carried out at room temperature - 100°C.

6. The method for synthesizing 4,4',4''-triaminotriphenylmethane according to claim 1, characterized in that, In step 2, the mass ratio of 4,4',4''-tris(N,N'-dibenzylaminophenyl)methane to the organic solvent is 1:5-1:10; The organic solvent is selected from at least one of toluene, methanol, ethanol, propanol, butanol, tetrahydrofuran, ethylene glycol, ethyl acetate, tert-butyl acetate, N,N-dimethylformamide, and water.

7. The method for synthesizing 4,4',4''-triaminotriphenylmethane according to claim 1, characterized in that, In step 2, the pressure range of the hydrogen gas is 0.4-2 MPa.

8. The method for synthesizing 4,4',4''-triaminotriphenylmethane according to claim 1, characterized in that, In step 2, the purification process includes: after the reaction is complete, distilling to remove excess solvent from the mixed system to obtain the residue, which is the triaminotriphenylmethane, wherein the purity of the 4,4',4''-triaminotriphenylmethane is not less than 95%.

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