CN102311328A - Method for preparing acetophenone - Google Patents

Abstract

The preparation method of acetophenone adopts cobalt and pyridine as the Dawson type molybdomolybdovanadium polyoxometalate and bromide as counter ions as a catalyst, and in this catalyst, the mol ratio of cobalt to Dawson type molybdovanadium heteropolyacid is 1～5:1, the molar ratio of pyridine Cpyr=(C ₁₆ H ₃₂ C ₅ H ₄ N) ⁺ to Dawson type molybdovanadium heteropolyacid is 1～10:1; the molar ratio of bromide to the aforementioned main catalyst is 0.1～ 2:1; ethylbenzene and oxygen source are used as reactants, the amount of catalyst added per 100ml of ethylbenzene is 3-8g, the reaction temperature is 45-95°C, and the reaction time is 4-11 hours.

Description

The preparation method of acetophenone

technical field

The present invention relates to a process for the preparation of acetophenone.

Background technique

At present, when benzene and acetyl chloride are used in industry to synthesize acetophenone in the presence of aluminum trichloride, strong acid will be generated after the reaction, which will easily cause corrosion of production equipment and environmental pollution; acetophenone is prepared by direct air oxidation of ethylbenzene When , the conversion rate of the catalytic system is not high and there are many by-products.

Contents of the invention

The purpose of this invention is to provide a kind of preparation method of acetophenone.

The present invention is a preparation method of acetophenone, which is characterized in that cobalt and pyridine are used as the Dawson type molybdenum vanadium polyoxometalate and bromide as the counter ions as the catalyst, in this catalyst, cobalt and molybdenum vanadium of the Dawson type The mol ratio of heteropolyacid is 1～5: 1, and the mol ratio of pyridine Cpyr=(C ₁₆ H ₃₂ C ₅ H ₄ N) ⁺ and Dawson type phosphomolybdenum vanadium heteropolyacid is 1～10: 1; Bromide and aforementioned The molar ratio of the main catalyst is 0.1-2:1; ethylbenzene and oxygen source are used as reactants, the amount of catalyst added per 100ml of ethylbenzene is 3-8g, the reaction temperature is 45-95°C, and the reaction time is 4-11 hours.

Compared with the traditional cobalt salt catalytic oxidation method, the present invention has the following advantages: (1) the reaction is completed in one step, and the process is simple; (2) the reaction temperature is 45-95°C, and the conditions are mild; (3) the conversion rate of ethylbenzene is high; (4) the selectivity of acetophenone is high; (5) oxidizing agent is hydrogen peroxide, hydrogen peroxide, tert-butyl hydroperoxide, air, oxygen, and the price is relatively cheap, and has no pollution to environment; (6) catalyst can be separated with solution, Renewable and reusable. Therefore, it is an economical and environmentally friendly synthesis method.

Description of drawings

Figure 1 is the XRD spectrum of (Cpyr) ₄ Co _2.5 P ₂ Mo ₁₅ V ₃ O ₆₂ , and Figure 2 is the ³¹ P NMR spectrum of (Cpyr) ₄ Co _2.5 P ₂ Mo ₁₅ V ₃ O ₆₂ .

Specific implementation method

Example 1:

Catalyst: Hexadecylpyridine is used to provide pyridinium cation, and Dawson type phosphomolybdovanadium heteropolyacid is used as raw material, wherein the molar ratio of hexadecylpyridine to H ₉ P ₂ Mo ₁₅ V ₃ O ₆₂ is 4:1, synthesized The steps are as follows: Dissolve H ₉ P ₂ Mo ₁₅ V ₃ O ₆₂ and cetylpyridine bromide in hot water at 60°C and PH=2, and dissolve the cetylpyridine bromide solution under magnetic stirring. , slowly drop it into the H ₇ P ₂ Mo ₁₇ VO ₆₂ aqueous solution from the dropping funnel, a large amount of egg yellow precipitates will be formed during the dropping process, after the drop is completed, age the reaction mixture for 2-3 hours, filter it with suction, and then Wash the precipitate with boiling water, absolute ethanol, and diethyl ether in sequence, and then place it in a fume hood overnight. After the diethyl ether evaporates, dry it in a vacuum oven at 80°C to obtain the preliminary product (Cpyr) ₄ H ₅ P ₂ Mo ₁₅ V ₃ O ₆₂ .

Basic cobalt carbonate (2CoCO ₃ 3Co(OH) ₂ xH ₂ O) was used to provide the cobalt source, and the preliminary product (Cpyr) ₄ H ₅ P ₂ Mo ₁₅ V ₃ O ₆₂ was used as the raw material, where (2CoCO ₃ 3Co( The molar ratio of OH) ₂ ·xH ₂ O) to (Cpyr) ₄ H ₅ P ₂ Mo ₁₅ V ₃ O ₆₂ is 0.5:1. In a 100ml three-necked flask equipped with a condenser tube and a thermometer, add 0.025mol ethylbenzene, 10mL glacial acetic acid and a certain amount of catalyst, heat to a certain temperature under electromagnetic stirring, and add a certain amount of tert-butyl hydroperoxide drop by drop , the dropping time is about 50 minutes. After the reaction is finished, pour the reaction solution into the separatory funnel, let it stand for stratification, extract the filtrate for product analysis, detect the composition of the oxidation product by gas chromatography, and use the internal standard method for quantitative analysis. The conversion rate of ethylbenzene is 81.55%, and the selectivity of acetophenone reaches 92.49%.

Embodiment 2～9:

According to the method and steps of Example 1, the ratio of cetylpyridine to H ₉ P ₂ Mo ₁₅ V ₃ O ₆₂ was changed, and the molar ratios were 1:1, 2:1, 3:1, and 5:1, respectively. , 6:1, 7:1, 8:1, 9:1, and then change the ratio of its initial product and basic cobalt carbonate (2CoCO ₃ 3Co(OH) ₂ xH ₂ O), the corresponding molar ratio Respectively: 0.8: 1, 0.7: 1, 0.6: 1, 0.4: 1, 0.3: 1, 0.2: 1, 0.1: 1, the result is that the conversion rate of ethylbenzene is less than 81.55%, and the selectivity of acetophenone is less than 92.49% %.

Embodiment 10～12:

According to the method and steps of Example 1, the vanadium content of the Dawson type molybdovanadium heteropolyacid was changed to H ₇ P ₂ Mo ₁₇ VO ₆₂ , H ₈ P ₂ Mo ₁₆ V ₂ O ₆₂ , H ₁₀ P ₂ Mo ₁₄ V ₄ O ₆₂ , the results are respectively 63.24% conversion of ethylbenzene and less than 73.24% selectivity of acetophenone; 80.85% conversion of ethylbenzene and 94.12% selectivity of acetophenone; 54.85% conversion of ethylbenzene , the selectivity of acetophenone is 80.16%.

Embodiment 13～15:

According to the method and steps of Example 1, the type of oxygen source was changed to hydrogen peroxide, air, and oxygen respectively. The selectivity of ethyl ketone is 91.53%; the conversion rate of ethylbenzene is 85.99% and the selectivity of acetophenone is 88.28%.

Figure 1 is the XRD spectrum of (Cpyr) ₄ Co _2.5 P ₂ Mo ₁₅ V ₃ O ₆₂ , the diffraction peaks of (Cpyr) ₄ Co _2.5 P ₂ Mo ₁₅ V ₃ O ₆₂ are mainly concentrated at 2θ=7°～9°, In the four intervals of 14°～20°, 26°～30°, and 37°～39°, the intensity of the diffraction peak at 2θ=7°～9° is the strongest, and the intensity of the diffraction peak at 2θ=26°～30° is the second Among them, the intensity of the diffraction peak at 2θ=37°～39° is the weakest, which is consistent with the literature (Liu Xia, Zhao Jun, Feng Changgen, etc., Synthesis and Spectral Research of Dawson Type Phosphomolybdenum Vanadium Glycine Heteropoly Compounds Substituted by Three Vanadium, Spectroscopy It is consistent with the chemical shift of the Dawson structure molybdovanadium heteropolyacid salt provided by spectral analysis, 2006, 26(12), p2226～2228), indicating that the synthesized phosphoromolybdenum vanadium cobalt salt (Cpyr) ₄ Co _2.5 P ₂ Mo ₁₅ V ₃ O ₆₂ has a Dawson structure. Figure 2 is the ³¹ P NMR spectrum of (Cpyr) ₄ Co _2.5 P ₂ Mo ₁₅ V ₃ O ₆₂ , which is consistent with the literature (Yu Jianfeng, Liu Yan, Yang Yu, Wu Tonghao, etc., Dawson type molybdenum vanadium heteropoly The nature of the compound [J], Journal of Natural Sciences of Jilin University, 1996, 2 (1), p89 ~ 93.) The Dawson structure phosphomolybdovanadate heteropolyacid ³¹ PNMR chemical shifts provided are consistent, which again shows that the synthesized phosphorus Molybdenum vanadium cobalt salt (Cpyr) ₄ Co _2.5 P ₂ Mo ₁₅ V ₃ O ₆₂ has a Dawson structure.

Claims (2)

1. the preparation method of methyl phenyl ketone; It is characterized in that adopting cobalt and pyridine is catalyzer as the Dawson type phosphorus molybdenum-vanadium multi-metal oxygen hydrochlorate and the bromide of gegenion; In this catalyzer, the mol ratio of cobalt and Dawson type phosphorus molybdenum vanadium heteropolyacid is 1～5: 1, pyridine Cpyr=(C ₁₆H ₃₂C ₅H ₄N) ⁺Mol ratio 1～10: 1 with Dawson type phosphorus molybdenum vanadium heteropolyacid; Bromide and aforementioned Primary Catalysts mol ratio 0.1～2: 1; As reactant, the catalyst levels that adds in every 100ml ethylbenzene is 3～8g with ethylbenzene and oxygen source, and temperature of reaction is 45～95 ℃, and the reaction times is 4～11 hours.

2. according to the preparation method of the said methyl phenyl ketone of claim 1, it is characterized in that oxygen source is a ydrogen peroxide 50, perhaps is tertbutyl peroxide; Perhaps being air, perhaps is oxygen, calculates by every 100ml ethylbenzene; The add-on of ydrogen peroxide 50 is 50～150ml; The add-on of tertbutyl peroxide is 20～60ml, air 2-10L/h, oxygen 1-3L/h.

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