APPLICATION OF THE IONIC IRON (III) COMPLEX AS CATALYST IN PREPARATION OF BENZYLAMINE COMPOUND

Abstract

Disclosed is an application of an ionic iron (III) complex as a catalyst in preparation of a benzylamine compound, that is, an ionic iron (III) complex having a molecular formula of [(RNCHCHNR)CH][FeBr.sub.4] (R is tert-butyl) and containing 1,3-di-tert-butyl imidazolium cation is used as a catalyst, di-tert-butyl peroxide is used as an oxidizing agent, and a benzylamine compound is synthesized by oxidation reaction of a toluene/ethylbenzene compound with an aromatic amine. The present invention has a wide application range, and is applicable not only to a toluene compound containing a benzylic primary carbon-hydrogen bond but also to an ethylbenzene compound containing a benzyl secondary carbon-hydrogen bond. This is the first example of the preparation of a benzylamine compound by oxidation reaction of a toluene/ethylbenzene compound and an aromatic amine by an iron-based catalyst.

Claims

1. A method for preparing a catalyst for preparing a benzylamine compound comprising: adding 1,3-di-tert-butylimidazole bromide into a tetrahydrofuran solution of ferric tribromide, reacting at 60° C. for 24 h, removing tetrahydrofuran under vacuum, washing with hexane, drying and extracting with tetrahydrofuran, centrifugating to collecting a supernatant, and adding hexane to the supernatant to precipitate the catalyst at room temperature as a red brown crystal, wherein the catalyst is an ionic iron (III) complex having the following structure: ##STR00006##

2. The method of claim 1, further comprising: adding aryl compound, an arylamine, an oxidizing agent, and the catalyst to form a reaction mixture; and conducting a reaction by heating the reaction mixture to obtain the benzylamine compound, wherein: the benzylamine compound has the following structure: ##STR00007## the aryl compound has the following structure: ##STR00008## the arylamine has the following structure: ##STR00009## the oxidizing agent is di-tert-butyl peroxide; and R is hydrogen or methyl; R.sup.1 is cyano, nitro, trifluoromethyl or acetyl; and R.sup.2 is hydrogen or methyl; and Ar is phenyl, p-tert-butylphenyl, o-methylphenyl, mesitylphenyl, p-chlorophenyl, o-chlorophenyl, naphthyl, or thienyl.

3. The method of claim 2, wherein the reaction is conducted with the aryl compound as a reaction solvent.

4. The method of claim 2, wherein the reaction mixture is heated at 80 to 150° C. for 15 to 60 hours.

5. The method of claim 2, wherein a molar ratio of the oxidizing agent:the arylamine is 1:1-1.6; and a molar ratio of the catalyst:the arylamine is 1:5-20.

6. The method of claim 5, wherein the molar ratio of the oxidizing agent:the arylamine is 1:1.5; and the molar ratio of the catalyst:the arylamine is 1:10.

Description

EMBODIMENTS OF THE INVENTION

[0025] The present invention will be further described in combination with the following embodiments:

Example 1 Synthesis of Ionic Iron Complex Containing 1,3-di-tert-butylimidazole Cation (Molecular Formula [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH] [FeBr.SUB.4.])

[0026] 1, 3-Di-tert-butylimidazole bromide (0.26 g, 1.0 mmol) was added into the tetrahydrofuran solution of ferric tribromide (0.27 g, 0.9 mmol), reacting at 60° C. for 24 h. When the reaction was complete, the solvent was removed under vacuum, washed with hexane, dried, extracted with tetrahydrofuran, and centrifuged to collect the supernatant. Hexane was added to the supernatant to precipitate to obtain a red-brown crystal at room temperature, a yield of 89%.

[0027] Elemental Analysis

TABLE-US-00001 TABLE 1 C: (%) H: (%) N: (%) Theoretical value 23.73 3.80 5.03 Actual value 23.88 3.89 5.14

[0028] The complex [(.sup.tBuNCHCHN.sup.tBu)CH][FeBr.sub.4] existed in the form of ion pairs, where [FeBr.sub.4].sup.− was characterized by Raman spectroscopy and it was found to have a characteristic peak at 204 cm.sup.−1.

[0029] The cationic part of the complex, [(.sup.tBuNCHCHN.sup.tBu)CH].sup.+, was characterized by mass spectrometry and found to have a molecular ion peak at 181.1699. The theoretic molecular ion peak is at 181.1699. The measured results are consistent with the theoretic value.

[0030] It was confirmed that the obtained compound was the target compound, and the chemical structural formula is as follows:

##STR00005##

Example 2 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of p-Cyanoaniline and Toluene

[0031] In a reaction bottle, p-cyanoaniline (59 mg, 0.5 mmol), catalyst (28 mg, 0.05 mmol), di-tert-butyl peroxide (138 μL, 0.75 mmol), and toluene (7 mL) were added sequentially. The reaction was carried out at 120° C. for 24 hours. After the reaction was complete, the reaction mixture was cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:50, a yield of 88%.

[0032] When iron bromide (10 mol %) was used as the catalyst, the yield was only 8%. When tert-butyl hydroperoxide (1.5 times) was used as the oxidizing agent, the yield was only 22%.

[0033] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: .sup.1H NMR (400 MHz, CDCl.sub.3, TMS): 7.38-7.28 (m, 7H), 6.58-6.55 (m, 2H), 4.73 (s, 1H), 4.35 (s, 2H) ppm.

Example 3 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of p-Cyanoaniline and p-Tert-Butyltoluene

[0034] In a reaction bottle, p-cyanoaniline (59 mg, 0.5 mmol), catalyst (14 mg, 0.025 mmol), di-tert-butyl peroxide (138 μL, 0.75 mmol), and p-tert-butyltoluene (7 mL) were added sequentially. The reaction was carried out at 80° C. for 60 hours. After the reaction was completed, the reaction mixture was is cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:50, a yield of 86%.

[0035] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: .sup.1H NMR (400 MHz, CDCl.sub.3, TMS): 7.45 (m, 4H), 7.32 (d, J=7.9 Hz, 2H), 6.69-6.60 (m, 2H), 4.65 (s, 1H), 4.39 (s, 2H), 1.38 (s, 9H) ppm.

Example 4 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of p-Cyanoaniline and o-Xylene

[0036] In a reaction bottle, p-cyanoaniline (59 mg, 0.5 mmol), catalyst (14 mg, 0.025 mmol), di-tert-butyl peroxide (138 μL, 0.75 mmol), and o-xylene (7 mL) were added sequentially. The reaction was carried out at 90° C. for 52 hours. After the reaction was completed, the reaction mixture cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:30, a yield of 83%.

[0037] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: .sup.1H NMR (400 MHz, CDCl.sub.3, TMS): 7.50-7.45 (m, 2H), 7.35-7.21 (m, 4H), 6.68-6.61 (m, 2H), 4.57 (s, 1H), 4.37 (d, J=4.7 Hz, 2H), 2.42 (s, 3H) ppm.

Example 5 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of p-Cyanoaniline and Mesitylene

[0038] In a reaction bottle, adding p-cyanoaniline (59 mg, 0.5 mmol), catalyst (28 mg, 0.05 mmol), di-tert-butyl peroxide (92 μL, 0.5 mmol), and mesitylene (7 mL) were added sequentially. The reaction was carried out at 100° C. for 40 hours. After the reaction was completed, the action mixture was cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:10, a yield of 84%.

[0039] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: .sup.1H NMR (400 MHz, CDCl.sub.3, TMS): 7.52-7.39 (m, 2H), 7.01 (s, 3H), 6.74-6.58 (m, 2H), 4.75 (s, 1H), 4.35 (d, J=5.1 Hz, 2H), 2.38 (s, 6H) ppm.

Example 6 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of p-Cyanoaniline and p-Chlorotoluene

[0040] In a reaction bottle, p-cyanoaniline (59 mg, 0.5 mmol), catalyst (42 mg, 0.075 mmol), di-tert-butyl peroxide (138 μL, 0.75 mmol), and p-chlorotoluene (7 mL) were added sequentially. The reaction was carried out at 110° C. for 32 hours. After the reaction was completed, the reaction mixture was cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:50, a yield of 80%.

[0041] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: .sup.1H NMR (400 MHz, CDCl.sub.3, TMS): 7.51-7.46 (m, 2H), 7.43-7.39 (m, 2H), 7.22 (d, J=8.4 Hz, 2H), 6.61-6.56 (m, 2H), 4.77 (s, 1H), 4.36 (s, 2H) ppm.

Example 7 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of p-Cyanoaniline and o-Chlorotoluene

[0042] In a reaction bottle, p-cyanoaniline (59 mg, 0.5 mmol), catalyst (28 mg, 0.05 mmol), di-tert-butyl peroxide (138 μL, 0.75 mmol), and o-chlorotoluene (7 mL) were added sequentially. The reaction was carried out at 120° C. for 24 hours. After the reaction was completed, the reaction mixture cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:10, a yield of 82%.

[0043] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: .sup.1H NMR (400 MHz, CDCl.sub.3, TMS): 7.47-7.42 (m, 3H), 7.37 (d, J=4.2 Hz, 1H), 7.34-7.24 (m, 2H), 6.63 (d, J=8.8 Hz, 2H), 4.94 (s, 1H), 4.52 (d, J=5.9 Hz, 2H) ppm.

Example 8 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of p-Cyanoaniline and 1-Methylnaphthalene

[0044] In a reaction bottle, p-cyanoaniline (59 mg, 0.5 mmol), catalyst (56 mg, 0.1 mmol), di-tert-butyl peroxide (138 μL, 0.75 mmol), and 1-methylnaphthalene (7 mL) were added sequentially. The reaction was carried out at 130° C. for 18 hours. After the reaction was completed, the reaction mixture was cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:10, a yield of 82%.

[0045] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: 41 NMR (400 MHz, CDCl.sub.3, TMS): 8.03 (dd, J=7.8, 1.9 Hz, 1H), 8.01-7.94 (m, 1H), 7.90 (d, J=7.6 Hz, 1H), 7.65-7.57 (m, 2H), 7.50 (dd, J=8.8, 5.4, 1.8 Hz, 4H), 6.73-6.62 (m, 2H), 4.81 (d, J=5.1 Hz, 2H), 4.68 (s, 1H) ppm.

Example 9 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of p-Cyanoaniline and 2-Methylthiophene

[0046] In a reaction bottle, p-cyanoaniline (59 mg, 0.5 mmol), catalyst (56 mg, 0.1 mmol), di-tert-butyl peroxide (138 μL, 0.75 mmol), and 2-methylthiophene (7 mL) were added sequentially. The reaction was carried out at 130° C. for 38 hours. After the reaction was completed, the reaction mixture cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:10, a yield of 83%.

[0047] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: .sup.1H NMR (400 MHz, CDCl.sub.3, TMS): 7.47 (d, J=8.8 Hz, 2H), 7.29 (dd, J=5.0, 1.2 Hz, 1H), 7.06 (d, J=0.7 Hz, 1H), 7.04 (d, J=5.0 Hz, 1H), 6.68 (d, J=8.8 Hz, 2H), 4.77 (s, 1H), 4.60 (d, J=5.5 Hz, 2H) ppm.

Example 10 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of p-Trifluoromethylaniline and Toluene

[0048] In a reaction bottle, p-trifluoromethylaniline (64 mg, 0.5 mmol), catalyst (28 mg, 0.05 mmol), di-tert-butyl peroxide (147 μL, 0.8 mmol), and toluene (7 mL) were added sequentially. The reaction was carried out at 140° C. for 16 hours. After the reaction was completed, the reaction mixture was cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:50, a yield of 75%.

[0049] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: .sup.1H NMR (400 MHz, CDCl.sub.3, TMS): 7.38-7.26 (m, 7H), 6.58 (d, J=8.8 Hz, 2H), 4.31 (s, 3H) ppm.

Example 11 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of p-Acetylaniline and Toluene

[0050] In a reaction bottle, p-acetylaniline (68 mg, 0.5 mmol), catalyst (28 mg, 0.05 mmol), di-tert-butyl peroxide (147 μL, 0.8 mmol), and toluene (7 mL) were added sequentially. The reaction was carried out at 150° C. for 15 hours. After the reaction was completed, the reaction mixture was cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:100, a yield of 74%.

[0051] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: .sup.1H NMR (400 MHz, CDCl.sub.3, TMS): 7.82-7.79 (m, 2H), 7.36-7.27 (m, 5H), 6.60-6.57 (m, 2H), 4.69 (s, 1H), 4.39 (d, J=4.8 Hz, 2H), 2.47 (s, 3H) ppm.

Example 12 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of p-Cyanoaniline and Ethylbenzene

[0052] In a reaction bottle, p-cyanoaniline (59 mg, 0.5 mmol), catalyst (28 mg, 0.05 mmol), di-tert-butyl peroxide (147 μL, 0.8 mmol), and ethylbenzene (7 mL) were added sequentially. The reaction was carried out at 130° C. for 18 hours. After the reaction was completed, the reaction mixture was cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:5, a yield of 81%.

[0053] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: .sup.1H NMR (400 MHz, CDCl.sub.3, TMS): 7.34-7.28 (m, 6H), 7.26-7.21 (m, 1H), 6.48-6.45 (m, 2H), 4.70 (s, 1H), 4.51 (q, J=6.7 Hz, 1H), 1.53 (d, J=6.7 Hz, 3H) ppm.

Example 13 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of p-Nitroaniline and Ethylbenzene

[0054] In a reaction bottle, p-nitroaniline (69 mg, 0.5 mmol), catalyst (28 mg, 0.05 mmol), di-tert-butyl peroxide (138 μL, 0.75 mmol), and ethylbenzene (7 mL) were added sequentially. The reaction was carried out at 140° C. for 16 hours. After the reaction was completed, it is cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:20, a yield of 80%.

[0055] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: .sup.1H NMR (400 MHz, CDCl.sub.3, TMS): 7.98-7.97 (m, 2H), 7.37-7.30 (m, 4H), 7.27-7.23 (m, 1H), 6.47-6.43 (m, 2H), 4.95 (d, J=4.8 Hz, 1H), 4.58 (q, J=6.4 Hz, 1H), 1.57 (d, J=6.8 Hz, 3H) ppm.

Example 14 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of n-Methyl-p-Nitroaniline and Toluene

[0056] In a reaction bottle, n-methyl-p-nitroaniline (76 mg, 0.5 mmol), catalyst (42 mg, 0.075 mmol), di-tert-butyl peroxide (138 μL, 0.75 mmol), and toluene (7 mL) were added sequentially. The reaction was carried out at 140° C. for 16 hours. After the reaction was completed, the reaction mixture was cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:10, a yield of 68%.

[0057] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: .sup.1H NMR (400 MHz, CDCl.sub.3, TMS): 8.14 (d, J=9.4 Hz, 2H), 7.39 (d, J=7.6 Hz, 3H), 7.22 (d, J=7.1 Hz, 2H), 6.71 (d, J=9.4 Hz, 2H), 4.73 (s, 2H), 3.24 (s, 3H) ppm.

Example 15 [(.SUP.t.BuNCHCHN.SUP.t.Bu)CH][FeBr.SUB.4.] Catalyzed Reaction of n-Methyl-p-Cyanoaniline and Toluene

[0058] In a reaction bottle, n-methyl-p-cyanoaniline (66 mg, 0.5 mmol), catalyst (56 mg, 0.1 mmol), di-tert-butyl peroxide (138 μL, 0.75 mmol), and toluene (7 mL) were added sequentially. The reaction was carried out at 130° C. for 18 hours. After the reaction was completed, the reaction mixture was cooled to room temperature. The product was purified by column chromatography eluting with ethyl acetate/petroleum ether with a volume ratio of 1:10, a yield of 75%.

[0059] The product was dissolved in CDCl.sub.3 (ca. 0.4 mL), sealed, and characterized on a Unity Inova-400 NMR apparatus at room temperature: .sup.1H NMR (400 MHz, CDCl.sub.3, TMS): 7.52-7.46 (m, 2H), 7.37 (dd, J=25.5, 3.8 Hz, 3H), 7.22 (d, J=7.3 Hz, 2H), 6.77-6.71 (m, 2H), 4.67 (s, 2H), 3.18 (s, 3H) ppm.