CN107176898A - A kind of method that aldehyde ketone is prepared as catalyst efficient catalytic molecular oxygen oxidation alcohol using houghite - Google Patents

Abstract

The invention belongs to the technical field of liquid-phase catalytic oxidation, and provides a method for preparing aldehydes and ketones by using hydrotalcite-like catalysts as catalysts to efficiently catalyze molecular oxygen oxidation of alcohols. The catalyst can be expressed as A ^n– _‑Nix M‑LDHs (A ^n– ＝OH ^– , CO ₃ ^2– , CH ₃ COO ^– and PO ₄ ^3– ; M=Ga or In; Ni/M=(2 ~ 4): 1). In the presence of the catalyst, without adding any auxiliary agent, the aerobic oxidation reaction of alcohol is carried out under mild conditions to prepare aldehyde and ketone compounds. The hydrotalcite-like material in the present invention can be synthesized in large quantities and can be recycled; the method has the advantages of high selectivity and yield of aldehydes and ketones, mild reaction conditions, low cost, easy industrialization and the like.

Description

A kind of hydrotalcite-like catalyst to efficiently catalyze molecular oxygen oxidation of alcohols to prepare aldehydes and ketones method

technical field

The invention belongs to the field of liquid-phase catalytic oxidation, and specifically relates to a method for preparing aldehydes and ketones by using hydrotalcite-like catalysts as catalysts to efficiently catalyze molecular oxygen oxidation of alcohols.

technical background

Aldehydes and ketones are important chemical intermediates widely used in the synthesis and production of medicines, dyes and agrochemicals. The direct oxidation of alcohols is one of the important methods to prepare aldehydes. The traditional method of preparing aldehydes and ketones by oxidation of alcohols usually uses a large number of oxidants, such as manganese dioxide, chromium oxide, and periodate. The use of metered oxidants in industry tends to cause excessive oxidation of aldehyde products, and the selectivity of the reaction is often low. Moreover, these metal oxides are highly toxic, generate a large amount of solid waste, and cause heavy pollution, making it difficult to apply them on a large scale. Selecting a mild oxidant, such as oxygen or air, and using catalytic oxidation is an important way to solve this problem. Although the efficient synthesis of aldehydes and ketones can be achieved by using homogeneous catalytic systems such as Fe/TEMPO, these homogeneous catalysts and additives in the reaction process complicate the separation and purification of products. At present, a variety of heterogeneous catalytic systems, such as supported Pd, Pt, Au, and Ru catalysts, have been developed for the efficient oxidation of alcohols, but these noble metal-based catalytic systems often limit their wide industrial applications. The cost advantage of non-precious metal catalysts makes them more promising. Currently, potassium manganese octahedral molecular sieves (OMS-2) (Makwana, V.D.; et al. J. Catal. 2002, 210, 46–52), MnGa oxides (Amini, M.; et al. J. Mol. Catal .A:Chem.2014,394,303–308), and NiAl hydrotalcites (Choudhary,B.M.; et al.Angew.Chem.Int.Ed.Engl. 2001,40,763–766.Kawabata,T.; et al.J .Mol.Catal.A:Chem.2005,236,206–215) and other heterogeneous catalysts have been used for this reaction, but the conversion and selectivity of the reaction are low, and the reaction efficiency still needs to be improved.

Therefore, the development of efficient catalytic systems based on cheap and readily available materials for the efficient oxidation of alcohols under mild conditions has great application potential. The invention aims to develop a method for preparing aldehydes and ketones by using hydrotalcite-like catalysts as catalysts to efficiently catalyze molecular oxygen oxidation of alcohols.

Contents of the invention

The purpose of the present invention is to develop a method for preparing aldehydes and ketones by using hydrotalcite-like catalysts to efficiently catalyze molecular oxygen oxidation of alcohols. This method has the characteristics of low energy consumption, little pollution, high reaction efficiency, and simple reaction operation.

The catalytic oxidation reaction comprises the following steps: under liquid phase conditions, in an organic solvent, using hydrotalcite as a catalyst, oxygen-containing gas as an oxidizing agent, the alcohol is oxidized to produce one or both of aldehydes and ketones; the reaction temperature 20-80°C, and the reaction time is 0.5-12 hours. The reaction formula is:

Wherein, R is phenyl, substituted aryl, substituted alkenyl or alkyl ^; R is H, phenyl, substituted aryl or alkyl ^;

In the reaction of the present invention, the hydrotalcite-like catalyst can be expressed as: A ^n– _-Nix M-LDHs (A ^n– ＝OH ^– , CO ₃ ^2– , CH ₃ COO ^– or PO ₄ ^3– ; M= Ga or In; Ni/M=(2～4)︰1);

In the reaction of the present invention, the molar ratio of Ni in the reaction substrate and the catalyst is 5～50;

In the reaction of the present invention, the solvent of reaction is mesitylene, toluene, acetonitrile, dioxane and n-octane;

Compared with the prior art, the present invention has the following advantages and effects:

(1) The method for preparing aldehydes and ketones by oxidation of alcohols provided by the present invention adopts a heterogeneous catalytic system to realize efficient oxidation of alcohols to generate aldehydes or ketones under mild conditions. The problem of low catalyst activity and the need to add various additives under mild conditions is solved.

(2) The catalytic reaction method of the present invention has good substrate applicability, and can efficiently catalyze various alcohol reactions to generate corresponding aldehydes and ketones.

Description of drawings

The structure of the catalyst OH ^– -Ni ₃ Ga-LDH sample is illustrated by Figure 1 and Figure 2. Figure 1OH ^– -Ni ₃ Ga-LDH sample XRD pattern; Figure 2OH ^– -Ni ₃ Ga-LDH sample SEM pattern.

detailed description

The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

The catalyst A ^n– _-Nix M-LDHs used for the oxidation of alcohols to prepare aldehydes or ketones according to the present invention can be prepared according to the following examples 1-3:

Example 1

Prepare 200 mL of mixed salt solution of 0.16 mol/L nickel nitrate hexahydrate and 0.08 mol/L gallium nitrate, and prepare 200 mL of mixed alkali solution of 0.2 mol/L sodium hydroxide and 0.2 mol/L ammonia water. Under the protection of N ₂ , the two mixed solutions prepared above were slowly added dropwise to 100 mL of water at 25 °C at the same time. During the dropping process, stir vigorously, and control the pH value of the system to maintain within the range of 10.0±0.2. After the dropping is completed, continue to stir for 6 hours, then age at 70°C for 12 hours, filter with suction, and wash with deionized water until neutral , dried at 70°C for 24h, and ground into powder. Obtain OH ^– -Ni ₂ Ga-LDH samples.

Example 2

Prepare 200 mL of 0.16 mol/L nickel nitrate hexahydrate and 0.08 mol/L gallium nitrate mixed salt solution, and prepare 200 mL of 0.2 mol/L sodium hydroxide and 0.04 mol/L sodium carbonate mixed alkali solution. At 25°C, slowly add the two mixed solutions prepared above dropwise into 100 mL of water at the same time. During the dropping process, stir vigorously, and control the pH value of the system to maintain within the range of 10.0±0.2. After the dropping is completed, continue to stir for 6 hours, then age at 70°C for 12 hours, filter with suction, and wash with deionized water until neutral , dried at 70°C for 24h, and ground into powder. CO ₃ ^2– -Ni ₂ Ga-LDH samples were obtained.

Example 3

Prepare 200 mL of mixed salt solution of 0.16 mol/L nickel nitrate hexahydrate and 0.08 mol/L indium nitrate, and 200 mL of mixed alkali solution of 0.2 mol/L sodium hydroxide and 0.04 mol/L sodium carbonate. Under the condition of 25°C, slowly add the two mixed solutions prepared above dropwise into 100 mL of water at the same time. During the dropping process, stir vigorously, and control the pH value of the system to maintain within the range of 9.5 to 10.0. After the dropping is completed, continue to stir for 6 hours, then age at 70°C for 12 hours, filter with suction, and wash with deionized water until neutral , dried at 70°C for 24h, and ground into powder. CO ₃ ^2– -Ni ₂ In-LDH samples were obtained.

The method for preparing aldehydes and ketones by using hydrotalcite-like catalysts as catalysts to catalyze the oxygen oxidation of alcohol molecules can be illustrated by Examples 4-10:

The catalytic activity of embodiment 4 different Ni-containing hydrotalcite catalysts

Typical reaction steps are as follows: add 0.108g (1mmol) benzyl alcohol, a certain amount of catalyst (the molar ratio of benzyl alcohol to Ni in the catalyst is 10), mesitylene 5mL, add in the reactor, feed oxygen, react under normal pressure, 60 The reaction was stirred at ℃ for 5h. The solid catalyst was removed by filtration, and the gas chromatography internal standard method (chlorobenzene was used as internal standard) was used to analyze the content of benzaldehyde in the liquid, and the calculated yield was 83%.

The reaction results are shown in Table 1.

Table 1 Catalytic reaction results of different hydrotalcite catalysts

serial number catalyst Reaction time/h Conversion rate/% selectivity/% 1 CO ₃ ^2– -Ni ₂ Ga-LDH 5 62 100 2 OH ^– -Ni ₂ Ga-LDH 5 82 100 3 OH ^– -Ni ₃ Ga-LDH 5 98 100 4 OH ^– -Ni ₄ Ga-LDH 5 90 100 5 CO ₃ ^2– -Ni ₂ In-LDH 5 72 100 6 OH ^– -Ni ₂ In-LDH 5 81 100 7 OH ^– -Ni ₃ In-LDH 5 86 100 8 (comparison results) CO ₃ ^2– -Ni ₂ Al-LDH 8 26 100 9 (comparison results) CO ₃ ^2– -Ni ₂ Fe-LDH 8 38 100

It can be seen from Table 1 that under normal pressure conditions, NiGa and NiIn hydrotalcites have excellent catalytic activity in catalyzing the reaction of molecular oxygen oxidation of alcohols to aldehydes and ketones. When OH ^– -Ni ₃ Ga-LDH was used as the catalyst, the conversion of benzyl alcohol reached 98% within 5 hours, and the selectivity of benzaldehyde was 100%. Compared with the comparative results, the catalytic system of the present invention has obvious advantages.

Example 5

Add 0.108g (1mmol) benzyl alcohol, OH ^– -Ni ₃ Ga-LDH 2.8mg (the molar ratio of benzyl alcohol to Ni in the catalyst is 50), mesitylene 5mL into the reactor, feed oxygen, and react under normal pressure , Stir the reaction at 60°C for 5h. The solid catalyst was separated and removed by filtration, and the content of benzaldehyde in the liquid was analyzed by gas chromatography internal standard method (chlorobenzene was used as internal standard), and the calculated yield was 58%.

Example 6

Add 0.108g (1mmol) benzyl alcohol, OH ^- -Ni ₃ Ga-LDH 28mg (the molar ratio of benzyl alcohol to Ni in the catalyst is 5), mesitylene 5mL into the reactor, feed oxygen, and react under normal pressure, The reaction was stirred at 60°C for 2h. The solid catalyst was separated and removed by filtration, and the content of benzaldehyde in the liquid was analyzed by gas chromatography internal standard method (chlorobenzene was used as internal standard), and the calculated yield was 100%.

Example 7

Add 0.108g (1mmol) benzyl alcohol, OH ^- -Ni ₃ Ga-LDH 14mg, n-octane 5mL into the reactor, feed oxygen, react under normal pressure, and stir at 60°C for 5h. The solid catalyst was separated and removed by filtration, and the content of benzaldehyde in the liquid was analyzed by gas chromatography internal standard method (chlorobenzene was used as internal standard), and the calculated yield was 91%.

Example 8 Application of this method in the reaction of other alcohols to oxidize aldehydes and ketones

The typical reaction steps are as follows: Add 1 mmol of the raw material alcohol shown in Table 2, 14 mg of OH ^– -Ni ₃ In-LDH, and 5 mL of mesitylene into the reactor, feed oxygen, react under normal pressure, and stir at 60 ° C Respond for a certain amount of time. The solid catalyst was separated and removed by filtration, the content of the product in the liquid was analyzed by gas chromatography internal standard method (chlorobenzene was used as internal standard), and the yield was calculated.

The results are shown in Table 2.

Table 2 Oxidation results of different reaction substrate alcohols

Continuation

The above examples are only used to illustrate the content of the present invention, in addition, the present invention also has other implementations. However, all technical solutions formed by equivalent replacement or equivalent deformation fall within the protection scope of the present invention.

Claims (4)

1. A method for preparing aldehydes and ketones by using hydrotalcite-like catalysts to efficiently catalyze molecular oxygen oxidation alcohols, the catalytic oxidation reaction comprises the steps of: under liquid phase conditions, in an organic solvent, using hydrotalcite-like catalyzers as catalyzers, oxygen-containing gas as Oxidant, oxidizing alcohol to produce aldehyde or ketone; the reaction temperature is 20-80°C, the reaction time is 0.5-12h, and the reaction formula is: Wherein, R ¹ is phenyl, substituted aryl, substituted alkenyl or alkyl; R ² is H, phenyl, substituted aryl or alkyl. 2. The method according to claim 1, characterized in that: the hydrotalcite-like catalyst can be expressed as: A ^n– _-Nix M-LDHs (A ^n– =OH ^– , CO ₃ ^2– , CH ₃ COO ^– or PO ₄ ^3– ; M=Ga or In; Ni/M=(2～4):1). 3. The method according to claim 1, characterized in that: the molar ratio of the reaction substrate to Ni in the catalyst is 5-50. 4. according to the described method of claim 1, it is characterized in that: the solvent of reaction is mesitylene, toluene, acetonitrile, dioxane or n-octane.