A cobalt metal-organic compound crystal, a preparation method thereof, and an application thereof

Abstract

The present invention discloses a cobalt metal-organic compound crystal, a preparation method and an application thereof, relating to the technical field of metal-organic compounds. Its molecular formula is [Co(L1)2(HL2)(H2O)]·HL2·2H2O, wherein L1 represents 1,10-phenanthroline, and HL2 represents the negative ion obtained after dehydrogenation of the 2-carboxyl group in the 3-nitrophthalic acid molecule. The preparation process of the present invention is simple, the operation is convenient, and the product purity is high; the prepared cobalt metal compound crystal shows good catalytic performance in the reaction of phenol hydroxylation to form dihydroxybenzene, the reaction conditions are mild, and the conversion rate can reach 52.6%.

Description

Technical Field

[0001] The present invention relates to the technical field of metal-organic compounds, and particularly relates to a cobalt metal-organic compound crystal, a preparation method thereof, and an application thereof. Background Art

[0002] Metal-organic compound crystal engineering has attracted great interest due to its potential applications in catalysis, chirality, conductivity, luminescence, magnetism, spin transition, nonlinear optics, and porosity or zeolite behavior. In recent years, the progress of metal-organic compound materials containing cobalt elements in the field of catalysis has been remarkable and has been successfully applied to various catalytic reactions.

[0003] So far, various metal-organic compounds have performed well in many fields such as catalysis. However, when using metal-organic compounds prepared with cobalt as the coordination center to catalyze the hydroxylation of phenol to prepare dihydroxybenzene, there are problems such as low catalytic efficiency and complex processes, which greatly limit the large-scale application of such catalysts in this catalytic field. Summary of the Invention

[0004] Based on the problems existing in the current technology, the present invention proposes a cobalt metal-organic compound crystal, a preparation method thereof, and an application thereof. The prepared cobalt metal compound crystal shows good catalytic performance in the reaction of hydroxylation of phenol to produce dihydroxybenzene.

[0005] A cobalt metal-organic compound crystal proposed by the present invention is characterized in that its molecular formula is [Co(L 1 ) 2 (HL 2 )(H 2 O)]·HL 2 ·2H 2 O, wherein L 1 represents 1,10-phenanthroline, and HL 2 represents the negative ion obtained after dehydrogenation of the 2-carboxyl group in the 3-nitrophthalic acid molecule; its structural formula is shown in formula (I):

[0006]

[0007] Preferably, the cobalt metal-organic compound crystal is in the triclinic system, the space group is P-1, and the unit cell parameters are: α = 73.700(8)°, β = 71.729(8)°, γ = 81.744(7)°.

[0008] The present invention also proposes a preparation method of the above cobalt metal-organic compound crystal, which is to use Co(NO 3 ) 2 ·6H 2O, 1,10 - phenanthroline and 3 - nitrophthalic acid are dissolved in an ethanol - aqueous solution according to a molar ratio of 1:2:2, and the mixture is subjected to a constant - temperature reaction at 180 °C for 60 h. After cooling to room temperature, orange - red square - shaped crystals are obtained.

[0009] Preferably, in the ethanol - aqueous solution, the volume ratio of ethanol to water is 1:1.

[0010] Preferably, it is cooled to room temperature at a rate of 5 °C / h.

[0011] The present invention also proposes the application of the above - mentioned cobalt metal - organic compound crystal in the catalytic hydroxylation of phenol to prepare dihydroxybenzene.

[0012] Beneficial effects: The present invention proposes a new cobalt metal - compound crystal synthesized with 1,10 - phenanthroline and 3 - nitrophthalic acid as organic ligands, and this compound crystal is obtained under hydrothermal / solvothermal synthesis conditions; the preparation process of the present invention is simple, easy to operate, and the product has high purity; the prepared cobalt metal - compound crystal shows good catalytic performance in the reaction of hydroxylation of phenol to form dihydroxybenzene, with mild reaction conditions and a conversion rate of up to 52.6%. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the crystal structure diagram of the cobalt metal - organic compound of the present invention;

[0014] Figure 2 It is the molecular crystal cell arrangement and packing diagram of the cobalt metal - organic compound of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Next, the technical solutions of the present invention will be described in detail through specific examples.

[0016] EXAMPLE

[0017] A preparation method of a cobalt metal - organic compound crystal is as follows: Weigh 0.2 mmol of 1,10 - phenanthroline, 0.2 mmol of 3 - nitrophthalic acid and 0.1 mmol of Co(NO 3 ) 2 ·6H 2 O, put them into a polytetrafluoroethylene tube, and then add an ethanol - aqueous solution (V 乙醇 :V 水 = 1:1) to make the filling degree in the polytetrafluoroethylene tube 70%. Seal this polytetrafluoroethylene tube in a stainless - steel autoclave, react at 180 °C for 60 h, and then cool it to room temperature at a rate of 5 °C per hour to obtain orange - red square - shaped cobalt metal - organic compound crystals, with a yield of 41%.

[0018] The prepared cobalt metal - organic compound crystal is subjected to structure characterization.

[0019] 1. Elemental analysis

[0020] Theoretical values: C 53.76%, H 3.38%, N 9.41%; Measured values: C 53.04%; H 3.11%; N 9.73%.

[0021] 2. Infrared spectroscopy analysis

[0022] The main IR absorption peaks of the product are (cm -1 ): 3410, 1630, 1560, 617;

[0023] 3. Determination of the crystal structure of the cobalt metal-organic compound

[0024] The crystal structure of the crystal material was determined and analyzed by X-ray diffraction. The crystal structure diagram and the crystal cell arrangement and packing diagram are shown in Figure 1 and Figure 2 respectively. The relevant crystallographic data are shown in Table 1, and the data of typical bond lengths and bond angles are shown in Table 2 and Table 3.

[0025] Table 1 Crystal data of the cobalt metal-organic compound crystal

[0026]

[0027]

[0028] Table 2 Typical bond lengths of the cobalt metal-organic compound crystal Data

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036] Table 3 Data of typical bond angles (°) of the cobalt metal-organic compound crystal

[0037]

[0038]

[0039]

[0040]

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[0042]

[0043]

[0044]

[0045] The prepared cobalt metal-organic compound is used in the reaction of catalyzing phenol hydroxylation, and the principle of this reaction is as follows:

[0046]

[0047] The specific operation is as follows: Weigh 1.0 g of phenol, dissolve it in 20 ml of ethanol-water (volume ratio 1:1), and place it in a 50-ml three-necked round-bottom flask; then add 10 mg of the cobalt metal-organic compound crystal material as a catalyst; and then slowly drop in 5 ml of 30% H 2 O 2 . Under the condition of a constant temperature water bath at 50 °C, reflux and stir the reaction for 5 h, and then cool it. Use a liquid chromatograph to detect hydroquinone, and the conversion rate is 52.6%.

[0048] As mentioned above, it is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A cobalt metal-organic compound crystal, Characterized in that, Its molecular formula is [Co(L 1 ) 2 (HL 2 )(H 2 O)]·HL 2 ·2H 2 O, where L 1 represents 1,10-phenanthroline, HL 2 represents the negative ion obtained after dehydrogenation of the 2-carboxyl group in the 3-nitrophthalic acid molecule; its structural formula is shown in Formula (I): The cobalt metal-organic compound crystal is triclinic, with the space group of P-1 and the unit cell parameters as follows: α = 73.700(8)°, β = 71.729(8)°, γ = 81.744(7)°.

2. The preparation method of the cobalt metal-organic compound crystal according to claim 1, Characterized in that, Dissolve Co(NO 3 ) 2 ·6H 2 O, 1,10-phenanthroline and 3-nitrophthalic acid in an ethanol aqueous solution according to a molar ratio of 1:2:2, react at a constant temperature of 180 °C for 60 h, and cool to room temperature to obtain orange-red block-shaped crystals.

3. The preparation method of the cobalt metal-organic compound crystal according to claim 2, Characterized in that, In the ethanol aqueous solution, the volume ratio of ethanol to water is 1:

1.

4. The preparation method of the cobalt metal-organic compound crystal according to claim 2, Characterized in that, Cool down to room temperature at a rate of 5 °C / h.

5. The application of the cobalt metal-organic compound crystal according to claim 1 in the catalytic hydroxylation of phenol to prepare dihydroxybenzene.

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