A method for preparing aromatic aldehydes or fatty aldehydes by electrocatalysis

Abstract

The present invention discloses an electrocatalytic preparation method of aromatic aldehyde or fatty aldehyde compounds. Aromatic alcohol or fatty alcohol compounds are used as reactants and prepared by electrocatalytic oxidation. In a non-diaphragm electrolyzer, aromatic aldehyde or fatty aldehyde compounds are obtained by electrocatalytic oxidation reaction in an electrolyte. In the electrocatalytic oxidation reaction of the present invention, no toxic or dangerous oxidants are required, and "electrons" are clean reaction reagents, which are an important part of the development of a "green chemical industry"; in the electrocatalytic oxidation process, the conversion rate and selectivity can be controlled by changing the electrolyte concentration and substrate concentration; thereby obtaining high-purity and high-yield intermediates; in industrial production, the process flow is simplified, the production cost is reduced, and it is safe and environmentally friendly, suitable for large-scale promotion and application.

Description

Technical Field

[0001] The invention relates to a method for preparing a compound, and in particular to an electrocatalytic preparation method for an aromatic aldehyde or aliphatic aldehyde compound. Background Art

[0002] Aldehyde compounds are important intermediates in organic synthesis and have been widely used in the fields of medicine, food and flavors and fragrances. In existing domestic and foreign literature reports, the methods for synthesizing aromatic aldehydes mainly include toluene chlorination hydrolysis method [CN 101786947 B, 2010], gas phase / liquid phase oxidation method [US 4137259, 1979; Catalysis Today, 2000, 57 (3): 231-239], styrene oxidation method [Reaction Kinetics Mechanisms & Catalysis, 2016, 119 (1): 305-318.], benzyl alcohol oxidation method [CN 102875341 A, 2013], etc. Among them, the aldehyde obtained by the chlorination hydrolysis method is not of high purity and cannot meet the application in the medicine and food industries. The gas phase / liquid phase oxidation method usually requires high temperature and is prone to over-oxidation. The benzyl alcohol oxidation method uses metal salts or metal oxides to catalyze the oxidation of alcohols in a stoichiometric manner to prepare the corresponding ketones and aldehydes. Although traditional oxidants can be used to oxidize alcohols relatively easily, the amount of oxidant required is relatively large, the reaction is difficult to control, the selectivity is poor, and a large amount of toxic and harmful substances such as halides and heavy metals are produced. Therefore, finding new, greener and more efficient methods for synthesizing aldehyde molecules is a very challenging and research-worthy task. Summary of the invention

[0003] In order to solve the above problems of easy over-oxidation, generation of toxic and harmful substances and poor selectivity, the present invention provides an electrocatalytic preparation method of aromatic aldehyde or fatty aldehyde compounds, the chemical structure of the aromatic aldehyde or fatty aldehyde compound is shown in I, and the preparation reaction is as follows:

[0004]

[0005] R is selected from the group consisting of phenyl, 4-fluorophenyl, 4-methoxyphenyl, 4-methylphenyl, 2-fluorophenyl, 2-methoxyphenyl, 2-methylphenyl, 3-fluorophenyl, 3-methoxyphenyl, 3-methylphenyl, phenylvinyl, benzyl, furanyl, 4-formylfuranyl, methyl, ethyl, propyl, butyl, and pentyl;

[0006] The preparation is carried out by electrocatalytic oxidation. In a non-diaphragm electrolytic cell, aromatic alcohol or fatty alcohol compounds are used as reactants, and aromatic aldehyde or fatty aldehyde compound I is obtained by electrocatalytic oxidation reaction in an electrolyte.

[0007] Furthermore, the anode of the electrolytic cell is selected from a nickel oxide (NiO / NF) electrode or a nickel hydroxide (β-Ni(OH)2 / NF) electrode, and the surface NiO of the nickel oxide electrode or the surface β-Ni(OH)2 of the nickel hydroxide electrode is a catalyst for the electrocatalytic reaction.

[0008] Furthermore, the preparation method of the nickel oxide electrode or the nickel hydroxide electrode is as follows:

[0009] (1) adding nickel nitrate and ammonium nitrate into deionized water and stirring for 15 to 20 minutes to dissolve to obtain solution A;

[0010] (2) adding 25-28 wt % ammonia water to solution A under stirring to obtain solution B;

[0011] (3) transferring solution B to a petri dish, adding clean nickel foam, maintaining at 90° C. for 12 hours, rinsing with deionized water and anhydrous ethanol 2 to 5 times, and drying at 50 to 70° C. for 8 to 12 hours to obtain β-Ni(OH)2 / NF;

[0012] (4) β-Ni(OH)2 / NF is heated at 300-350°C in an argon atmosphere tube furnace for 1-3 hours to obtain NiO / NF.

[0013] Furthermore, the working electrode current density of the anode is 20 mA / cm 2 ~400mA / cm 2 ; The electrolysis temperature is 25℃~65℃.

[0014] Furthermore, the cathode of the electrolytic cell is selected from a platinum sheet electrode, a nickel foam electrode or a carbon rod electrode, preferably a platinum sheet electrode.

[0015] Furthermore, the solvent of the electrolyte is selected from any one or more of water, acetonitrile or tetrahydrofuran, preferably water.

[0016] Furthermore, the concentration of the aromatic alcohol or fatty alcohol compound in the electrolyte is 0.05 mol / L to 0.5 mol / L.

[0017] Furthermore, the electrolyte of the electrolyte solution is selected from one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, lithium carbonate or potassium bicarbonate, preferably potassium carbonate.

[0018] Furthermore, the concentration of potassium carbonate is 0.1 mol / L to 3 mol / L.

[0019] The beneficial effects of the present invention are:

[0020] (1) The electrocatalytic oxidation reaction of the present invention does not require toxic or dangerous oxidants. "Electrons" are clean reaction reagents, which is an important component of the development of the "green chemical industry".

[0021] (2) In the electrocatalytic oxidation process, the present invention can control the conversion rate and selectivity by changing the electrolyte concentration and substrate concentration, thereby obtaining a high-purity and high-yield intermediate.

[0022] (3) The present invention can simplify the process flow and reduce production costs in industrial production, and is safe and environmentally friendly, and is suitable for large-scale promotion and application. DETAILED DESCRIPTION

[0023] The following examples are intended to illustrate the present invention rather than to further limit the present invention.

[0024] Example 1

[0025] Preparation of Benzaldehyde by Electrocatalytic Oxidation

[0026]

[0027] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 1.5mmol (0.162g) benzyl alcohol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, the concentration of benzyl alcohol in the electrolyte is 0.3mol / L, the concentration of potassium carbonate in the electrolyte is 1.5mol / L, constant current 20mA electrolysis for 4h, the reaction solution is extracted with ethyl acetate, the organic layer is dried over anhydrous sodium sulfate, and rotary evaporated to obtain 0.153g benzaldehyde; yield 96%; 1 H NMR (400MHz, Chloroform-d) δ 10.01 (s, 1H), 7.87 (d, J = 8.2 Hz, 2H), 7.62 (t, J = 7.4 Hz, 1H), 7.52 (t, J = 7.6 Hz, 2H).

[0028] Example 2

[0029] Preparation of Benzaldehyde by Electrocatalytic Oxidation

[0030]

[0031] Install the anode (β-Ni(OH)2 / NF: 10×10mm) in the electrolytic cell 2 ) and cathode (platinum sheet: 10×10mm 2); add a magnetic stirrer, 1.5mmol (0.162g) benzyl alcohol, 7.5mol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 4h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.130g benzaldehyde; yield 82%; 1 H NMR (400MHz, Chloroform-d) δ 10.01 (s, 1H), 7.87 (d, J = 8.2 Hz, 2H), 7.62 (t, J = 7.4 Hz, 1H), 7.52 (t, J = 7.6 Hz, 2H).

[0032] Example 3

[0033] Preparation of Benzaldehyde by Electrocatalytic Oxidation

[0034]

[0035] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 1.5mmol (0.162g) benzyl alcohol, 2.5mol (0.345g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 4h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.137g benzaldehyde; yield 86%; 1 H NMR (400MHz, Chloroform-d) δ 10.01 (s, 1H), 7.87 (d, J = 8.2 Hz, 2H), 7.62 (t, J = 7.4 Hz, 1H), 7.52 (t, J = 7.6 Hz, 2H).

[0036] Example 4

[0037] Preparation of Benzaldehyde by Electrocatalytic Oxidation

[0038]

[0039] Install the anode (Ni(OH)2 / NF: 10×10mm) in the electrolytic cell 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 0.25mmol (0.027g) benzyl alcohol, 7.5mol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 40min, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.017g benzaldehyde; yield 66%; 1H NMR (400MHz, Chloroform-d) δ 10.01 (s, 1H), 7.87 (d, J = 8.2 Hz, 2H), 7.62 (t, J = 7.4 Hz, 1H), 7.52 (t, J = 7.6 Hz, 2H).

[0040] Example 5

[0041] Preparation of Benzaldehyde by Electrocatalytic Oxidation

[0042]

[0043] Install the anode (NiO / NF: 80×80mm) in the electrolytic cell 2 ) and cathode (nickel foam: 80×80mm 2 ); add a magnetic stirrer, 0.2 mol (21.6 g) benzyl alcohol, 1.2 mol (165.6 g) potassium carbonate to the electrolytic cell, add 800 mL of water, dissolve, electrolyze at a constant current of 1 A for 15 h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 19.9 g benzaldehyde; yield 94%; 1 H NMR (400MHz, Chloroform-d) δ 10.01 (s, 1H), 7.87 (d, J = 8.2 Hz, 2H), 7.62 (t, J = 7.4 Hz, 1H), 7.52 (t, J = 7.6 Hz, 2H).

[0044] Example 6

[0045] Preparation of 4-Fluorobenzaldehyde by Electrocatalytic Oxidation

[0046]

[0047] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 1.5mmol (0.189g) 4-fluorobenzyl alcohol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 4h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.171g 4-fluorobenzaldehyde; yield 92%; 1 H NMR (400MHz, Chloroform-d) δ9.97 (s, 1H), 7.92 (dd, J = 8.6, 5.5Hz, 2H), 7.21 (t, J = 8.6Hz, 2H).

[0048] Example 7

[0049] Preparation of 4-methoxybenzaldehyde by electrocatalytic oxidation

[0050]

[0051] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 1.5mmol (0.207g) 4-methoxybenzyl alcohol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 4h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.198g 4-methoxybenzaldehyde; yield 97%; 1 H NMR (400MHz, Chloroform-d) δ9.87 (s, 1H), 7.82 (d, J = 8.7Hz, 2H), 6.99 (d, J = 8.7Hz, 2H), 3.87 (s, 3H).

[0052] Example 8

[0053] Preparation of 4-Methylbenzaldehyde by Electrocatalytic Oxidation

[0054]

[0055] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 1.5mmol (0.183g) 4-methylbenzyl alcohol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 4h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.153g 4-methylbenzaldehyde; yield 85%; 1 H NMR (400MHz, Chloroform-d) δ9.96 (s, 1H), 7.78 (d, J = 8.1 Hz, 2H), 7.33 (d, J = 7.9 Hz, 2H), 2.43 (s, 3H).

[0056] Example 9

[0057] Preparation of 2-Fluorobenzaldehyde by Electrocatalytic Oxidation

[0058]

[0059] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 1.5mmol (0.189g) 2-fluorobenzyl alcohol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 4h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.166g 2-fluorobenzaldehyde; yield 89%; 1 H NMR (400MHz, Chloroform-d) δ10.37(s,1H),7.87(t,J=7.3Hz,1H),7.65–7.57(m,1H),7.27(t,J=7.7Hz,1H),7.21–7.14(m,1H).

[0060] Example 10

[0061] Preparation of 2-methoxybenzaldehyde by electrocatalytic oxidation

[0062]

[0063] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 1.5mmol (0.207g) 2-methoxybenzyl alcohol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 6h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.196g 2-methoxybenzaldehyde; yield 96%; 1 H NMR (400MHz, Chloroform-d) δ 10.44 (s, 1H), 7.79 (d, J = 7.7Hz, 1H), 7.56–7.46 (m, 1H), 7.03–6.91 (m, 2H), 3.87 (s, 3H).

[0064] Embodiment 11

[0065] Preparation of 2-Methylbenzaldehyde by Electrocatalytic Oxidation

[0066]

[0067] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2); add a magnetic stirrer, 1.5mmol (0.183g) 2-methylbenzyl alcohol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 4h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.144g 2-methylbenzaldehyde; yield 80%; 1 H NMR (400MHz, Chloroform-d) δ10.25(s,1H),7.78(d,J=7.6Hz,1H),7.50–7.42(m,1H),7.34(t,J=7.5Hz,1H),7.24(d,J=7.6Hz,1H),2.66(s,3H).

[0068] Example 12

[0069] Preparation of 3-Fluorobenzaldehyde by Electrocatalytic Oxidation

[0070]

[0071] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 1.5mmol (0.189g) 3-fluorobenzyl alcohol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 4h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.182g 4-methoxybenzaldehyde; yield 98%; 1 H NMR (400MHz, Chloroform-d) δ10.00 (s, 1H), 7.68 (d, J = 7.6Hz, 1H), 7.61–7.50 (m, 2H), 7.34 (tdd, J = 8.3, 2.6, 1.1Hz, 1H).

[0072] Embodiment 13

[0073] Preparation of 3-methoxybenzaldehyde by electrocatalytic oxidation

[0074]

[0075] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2); add a magnetic stirrer, 1.5mmol (0.207g) 3-methoxybenzyl alcohol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 6h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.196g 3-methoxybenzaldehyde; yield 96%; 1 H NMR (400MHz, Chloroform-d) δ9.84 (s, 1H), 7.32 (s, 2H), 7.26 (s, 1H), 7.04 (dd, J = 6.5, 3.0Hz, 1H), 3.73 (s, 3H).

[0076] Embodiment 14

[0077] Preparation of 3-Methylbenzaldehyde by Electrocatalytic Oxidation

[0078]

[0079] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 1.5mmol (0.183g) 3-methylbenzyl alcohol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 6h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.124g 3-methylbenzaldehyde; yield 69%; 1 H NMR (400MHz, Chloroform-d) δ9.98(s,1H),7.71–7.63(m,2H),7.46–7.36(m,2H),2.43(s,3H).

[0080] Embodiment 15

[0081] Preparation of Cinnamaldehyde by Electrocatalytic Oxidation

[0082]

[0083] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer to the electrolytic cell, 1.5mmol (0.201g) cinnamyl alcohol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 6h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.120g 4-methoxybenzaldehyde; yield 60%.1 H NMR (400MHz, Chloroform-d) δ9.71 (d, J = 7.7 Hz, 1H), 7.61–7.54 (m, 2H), 7.52–7.41 (m, 4H), 6.73 (dd, J = 16.0, 7.7 Hz, 1H).

[0084] Example 16

[0085] Preparation of Phenylacetaldehyde by Electrocatalytic Oxidation

[0086]

[0087] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 1.5mmol (0.183g) phenylethanol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 6h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.076g phenylacetaldehyde; yield 42%; 1 H NMR (400MHz, Chloroform-d) δ9.77 (s, 1H), 7.43–7.25 (m, 5H), 3.72 (d, J = 2.5Hz, 2H).

[0088] Embodiment 17

[0089] Preparation of Furfural by Electrocatalytic Oxidation

[0090]

[0091] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 1.5mmol (0.147g) furfuryl alcohol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 4h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.124g furfural; yield 86%; 1 H NMR (400MHz, Chloroform-d) δ9.67 (s, 1H), 7.72 (s, 1H), 7.29 (d, J = 3.7Hz, 1H), 6.64–6.61 (m, 1H).

[0092] Embodiment 18

[0093] Preparation of 2,5-diformylfuran by electrocatalytic oxidation

[0094]

[0095] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer to the electrolytic cell, 1.5mmol (0.189g) 5-hydroxymethylfurfural, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water to dissolve, electrolyze at a constant current of 20mA for 4h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.084g 2,5-diformylfuran; yield 45%; 1 H NMR (400MHz, Chloroform-d) δ9.87 (s, 2H), 7.34 (s, 2H).

[0096] Embodiment 19

[0097] Preparation of acetaldehyde by electrocatalytic oxidation

[0098]

[0099] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 2.5mmol (0.115g) ethanol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water, dissolve, electrolyze at a constant current of 20mA for 6h, and the reaction solution is detected by GC, with a yield of 36%.

[0100] Embodiment 20

[0101] Preparation of Propionaldehyde by Electrocatalytic Oxidation

[0102]

[0103] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 2.5mmol (0.150g) propanol, 7.5mmol (1.035g) potassium carbonate to the electrolytic cell, add 5mL water, dissolve, electrolyze at a constant current of 20mA for 6h, and detect the reaction solution by GC. The yield is 40%.

[0104] Embodiment 21

[0105] Preparation of n-butyraldehyde by electrocatalytic oxidation

[0106]

[0107] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 1.5mmol (0.185g) of n-butanol, 7.5mmol (1.035g) of potassium carbonate to the electrolytic cell, add 5mL of water to dissolve, electrolyze at a constant current of 20mA for 6h, and the reaction solution is detected by GC, with a yield of 40%.

[0108] Embodiment 22

[0109] Preparation of n-Valeraldehyde by Electrocatalytic Oxidation

[0110]

[0111] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 2.5mmol (0.220g) of n-pentanol, 7.5mmol (1.035g) of potassium carbonate to the electrolytic cell, add 5mL of water to dissolve, electrolyze at a constant current of 20mA for 6h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.097g of n-pentanal; yield 45%.

[0112] Embodiment 23

[0113] Preparation of n-hexanal by electrocatalytic oxidation

[0114]

[0115] Install the anode (NiO / NF: 10×10mm) in the electrolytic cell. 2 ) and cathode (platinum sheet: 10×10mm 2 ); add a magnetic stirrer, 2.5mmol (0.255g) of n-hexanol, 7.5mmol (1.035g) of potassium carbonate to the electrolytic cell, add 5mL of water to dissolve, electrolyze at a constant current of 20mA for 6h, extract the reaction solution with ethyl acetate, dry the organic layer with anhydrous sodium sulfate, and rotary evaporate to obtain 0.110g of n-hexanal; yield 44%.

Claims

1. A method for electrocatalytic preparation of aromatic aldehydes or aliphatic aldehyde compounds, characterized in that: The chemical structural formula of the aromatic aldehyde or aliphatic aldehyde compound is shown in I, and the preparation reaction is as follows: ，（Ⅰ)， R is selected from the group consisting of phenyl, 4-fluorophenyl, 4-methoxyphenyl, 4-methylphenyl, 2-fluorophenyl, 2-methoxyphenyl, 2-methylphenyl, 3-fluorophenyl, 3-methoxyphenyl, 3-methylphenyl, phenylvinyl, benzyl, furanyl, 4-formylfuranyl, methyl, ethyl, propyl, butyl, and pentyl; Preparation by electrocatalytic oxidation: in a non-diaphragm electrolyzer, aromatic alcohol or fatty alcohol compound is used as reactant, and aromatic aldehyde or fatty aldehyde compound I is obtained by electrocatalytic oxidation reaction in electrolyte; The anode of the electrolytic cell is selected from nickel oxide electrode NiO / NF or nickel hydroxide electrode β -Ni(OH)2 / NF, the surface layer NiO of the nickel oxide electrode or the surface layer NiO of the nickel hydroxide electrode β -Ni(OH)2 as a catalyst for the electrocatalytic reaction; The preparation method of the nickel oxide electrode or the nickel hydroxide electrode is as follows: (1) Add nickel nitrate and ammonium nitrate into deionized water and stir for 15 to 20 minutes to dissolve to obtain solution A; (2) adding 25-28 wt % ammonia water to solution A under stirring to obtain solution B; (3) Transfer solution B to a petri dish, add clean nickel foam, keep at 90°C for 12 hours, rinse with deionized water and anhydrous ethanol 2 to 5 times, and dry at 50 to 70°C for 8 to 12 hours to obtain β -Ni(OH)2 / NF; (4) β -Ni(OH)2 / NF was heated at 300-350°C in an argon atmosphere tube furnace for 1-3 hours to obtain NiO / NF.

2. The electrocatalytic preparation method of aromatic aldehyde or aliphatic aldehyde compounds according to claim 1, characterized in that: The working electrode current density of the anode is 20 mA / cm 2 ~ 400 mA / cm 2 ; The electrolysis temperature is 25℃~65℃.

3. The electrocatalytic preparation method of aromatic aldehyde or aliphatic aldehyde compounds according to claim 1, characterized in that: The cathode of the electrolytic cell is selected from a platinum sheet electrode, a nickel foam electrode or a carbon rod electrode.

4. The electrocatalytic preparation method of aromatic aldehyde or aliphatic aldehyde compounds according to claim 1, characterized in that: The solvent of the electrolyte solution is selected from any one or more of water, acetonitrile or tetrahydrofuran.

5. The electrocatalytic preparation method of aromatic aldehyde or aliphatic aldehyde compounds according to claim 1, characterized in that: The concentration of the aromatic alcohol or fatty alcohol compound in the electrolyte is 0.05 mol / L to 0.5 mol / L.

6. The electrocatalytic preparation method of aromatic aldehyde or aliphatic aldehyde compounds according to claim 1, characterized in that: The electrolyte of the electrolyte solution is selected from one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, lithium carbonate or potassium bicarbonate.

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