CN101628873B - Method for synthesizing beta-hydroxymethyl butyrate - Google Patents

Abstract

A method for synthesizing methyl β-hydroxybutyrate, which mainly includes adding 125-625mmol/L of propylene oxide to a methanol solution containing 250-1000mmol/L propylene oxide, 8-16mmol/L cobalt acetate and cadmium iodide catalyst Methyl formate, wherein the molar ratio of cobalt acetate and cadmium iodide is 1:9, the reaction solution is irradiated with a 100-400W high-pressure mercury lamp for 15-55 hours, and the reaction temperature is 25-60°C. Preferably, 300-900 mmol/L sodium acetate is added to the methanol solution containing 250-1000 mmol/L propylene oxide and 8-16 mmol/L catalyst. The invention makes the carbonylation reaction easy and safe to operate; the non-precious metal compound is used as the catalyst, which is easy to obtain and convenient to store and use. The product of the invention has low cost and is suitable for the synthesis of methyl β-hydroxybutyrate with small scale and high added value.

Description

A kind of method for synthesizing methyl β-hydroxybutyrate

technical field

The invention relates to a method for synthesizing methyl β-hydroxybutyrate.

Background technique

In recent years, as the demand for β-hydroxy acid esters in materials, medicine and industry has gradually increased, people's research on them has also been continuously strengthened. The traditional synthesis of β-hydroxy acid esters is the Reformatsky reaction. The reaction substrate of this method is α-halogenated ester, which is a commercial compound that is not easy to obtain, and a large amount of Zn powder is required in the reaction, and the yield of β-hydroxy acid ester is low, forcing people to find other methods to synthesize β - Hydroxy esters. So someone invented the carbonylation reaction of propylene oxide, carbon monoxide and methanol to synthesize methyl β-hydroxybutyrate. It uses Co ₂ (CO) ₈ as a catalyst and reacts at 24.5MPa and 130°C for 4 hours. Although this method is better than the above-mentioned traditional synthetic method, the yield of methyl β-hydroxybutyrate is as low as 40%. In order to increase the yield, it was proposed to add 3-OH-Py to the Co ₂ (CO) ₈ catalyst, react at 4.2MPa, 75°C for 9 hours, and the yield of methyl β-hydroxybutyrate can reach 92%. But the biggest disadvantage of this conventional carbonylation reaction method is that the reaction should be completed under high pressure (≥6.0MPa), and the catalyst is not easy to preserve and use. In addition, it is necessary to use toxic CO gas, so that this method can be used on a small scale. The application of fine products is subject to certain restrictions.

Contents of the invention

The purpose of the present invention is to provide a kind of raw material is nontoxic, and catalyst is easy to store and use, and the method for synthesizing methyl β-hydroxybutyrate on a small scale under normal pressure.

The technical scheme of the present invention is mainly: use propylene oxide and methyl formate as raw materials, use cobalt acetate Co(OAc) ₂ and cadmium iodide CdI ₂ as catalysts, and synthesize β-hydroxybutyric acid under normal pressure and photopromoting conditions Methyl ester method.

Reaction equation of the present invention is as follows:

The raw material of the present invention is propylene oxide and methyl formate, and wherein substrate is propylene oxide, and methyl formate is as C ₁ source.

The synthetic method of the present invention is as follows:

1. Preparation of reaction solution

1 Mix propylene oxide and methanol to prepare a methanol solution with a concentration of 250-1000mmol/L.

2 Mix the catalyst cobalt acetate Co(OAc) ₂ , cadmium iodide CdI ₂ and methanol to prepare a methanol solution with a concentration of 8-16 mmol/L, wherein the catalyst cobalt acetate:cadmium iodide=1:9 (molar ratio).

3 Mix the above catalyst methanol solution with the above propylene oxide methanol solution.

4 It is preferable to add sodium acetate to the above mixed solution to improve the catalytic activity of cobalt acetate and cadmium iodide, and its concentration in the mixed solution is 300-900mmol/L.

2. Synthesis

1 At room temperature, add 250-1000mmol/L propylene oxide, 8-16mmol/L catalyst or add 250-1000mmol/L propylene oxide, 8-16mmol/L catalyst and 300-900mmol/L sodium acetate to the above Add 125-625mmol/L methyl formate directly into the methanol solution at one time.

2 Simultaneously irradiate the reaction solution with a 100-400W high-pressure mercury lamp for 15-55 hours, and control the reaction temperature at 25-60°C.

3 The product obtained by the above method is methyl β-hydroxybutyrate methanol solution. This product can be directly applied, and in this case, n-decane is used as an internal standard, and the product is analyzed by gas chromatography, and the results measured by gas chromatography are used to calculate the yield of 13%-55%, and the gas chromatography-mass spectrometry instrument for product identification.

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

1. The carbonylation reaction of the present invention can basically proceed smoothly under the conditions of normal temperature, normal pressure, and simple salt catalysis of non-noble metals. The process of the reaction is regulated by turning on and off the light source, neither using toxic carbon monoxide nor requiring High pressure and other harsh reaction conditions are used instead of mild reaction conditions to complete the carbonylation reaction, which is easy to operate and safe to operate.

2. The present invention uses non-precious metal compounds Co(OAc) ₂ and CdI ₂ as catalysts, which are easy to obtain and convenient to store and use.

3. Because the raw materials and catalysts of the present invention are cheap, and the reaction conditions are mild again, the product cost of the present invention is greatly reduced.

4. The present invention is suitable for the synthesis of methyl β-hydroxybutyrate with small scale and high added value.

Description of drawings

Fig. 1 is the gas chromatography spectrogram of example 1 product of the present invention.

Fig. 2 is the spectrogram measured by the gas chromatography-mass spectrometer of the product of Example 1 of the present invention.

Fig. 3 is the gas chromatogram of the product of Example 2 of the present invention.

Fig. 4 is the spectrogram measured by the gas chromatography-mass spectrometer of the product of Example 2 of the present invention.

Figure 5 is a gas chromatogram of the product of Example 3 of the present invention.

Fig. 6 is the spectrogram measured by the gas chromatography-mass spectrometer of the product of Example 3 of the present invention.

Detailed ways

example 1

Propylene oxide (analytically pure) was mixed with methanol to prepare a methanol solution with a concentration of 250mmol/L. Mix the catalyst cobalt acetate, cadmium iodide and methanol to prepare a methanol solution with a concentration of 8mmol/L, wherein the total concentration of cobalt acetate and cadmium iodide is 8mmol/L, and the molar ratio of cobalt acetate and cadmium iodide is 1:9 . The above methanol solution of the catalyst was mixed with the above methanol solution of propylene oxide. Add sodium acetate in the above mixed solution, its concentration in the mixed solution is 300mmol/L. A 100W high-pressure mercury lamp is placed inside a quartz photoreactor with a hollow interlayer, and circulating water is passed into the interlayer, and the entire reactor is placed in a water tank filled with water to cool the light source. Add 4ml of methanol solution containing 250mmol/L propylene oxide, 8mmol/L catalyst cobalt acetate and cadmium iodide, and 300mmol/L sodium acetate into the quartz test tube, and attach the quartz test tube to the outer wall of the photoreactor. At room temperature, 125 mmol/L methyl formate was directly added to the above mixed solution at one time, and at the same time, a high-pressure mercury lamp was turned on to irradiate the reaction solution for 15 hours, and the reaction temperature was controlled at 25-60°C. The product that obtains makes internal standard with n-decane, carries out gas chromatography analysis, and with the result that gas chromatography records, please see accompanying drawing 1, calculates β-hydroxybutyric acid methyl ester yield 13%, uses gas chromatography- Mass spectrometry was used to identify the product, please refer to accompanying drawing 2, and it was determined to be methyl β-hydroxybutyrate.

Example 2

Propylene oxide (analytical pure) was mixed with methanol to prepare a methanol solution with a concentration of 1000mmol/L. Mix the catalyst cobalt acetate, cadmium iodide and methanol to prepare a methanol solution with a concentration of 16mmol/L, wherein the total concentration of cobalt acetate and cadmium iodide is 16mmol/L, and the molar ratio of cobalt acetate and cadmium iodide is 1:9 . The above methanol solution of the catalyst was mixed with the above methanol solution of propylene oxide. Add sodium acetate to the above mixed solution, and its concentration in the mixed solution is 900mmol/L. A 400W high-pressure mercury lamp is placed inside a quartz photoreactor with a hollow interlayer, and circulating water is passed into the interlayer, and the entire reactor is placed in a water tank filled with water to cool the light source. Add 4ml of methanol solution containing 1000mmol/L propylene oxide, 16mmol/L catalyst cobalt acetate and cadmium iodide, and 900mmol/L sodium acetate into the quartz test tube, and attach the quartz test tube to the outer wall of the photoreactor. At room temperature, directly add 625mmol/L methyl formate to the above mixed solution at one time, turn on the high-pressure mercury lamp to irradiate the reaction solution for 55 hours, and control the reaction temperature at 25-60°C. The obtained product was analyzed by gas chromatography with n-decane as an internal standard, and the results obtained by gas chromatography were shown in Figure 3, and the calculated yield was 27%. Product identification was carried out by gas chromatography-mass spectrometry, see accompanying drawing 4, and it was determined to be methyl β-hydroxybutyrate.

Example 3

Propylene oxide (analytically pure) was mixed with methanol to prepare a methanol solution with a concentration of 250mmol/L. Mix the catalyst cobalt acetate, cadmium iodide and methanol to prepare a methanol solution with a concentration of 12mmol/L, wherein the total concentration of cobalt acetate and cadmium iodide is 12mmol/L, and the molar ratio of cobalt acetate and cadmium iodide is 1:9 . The above methanol solution of the catalyst was mixed with the above methanol solution of propylene oxide. Add sodium acetate to the above mixed solution, and its concentration in the mixed solution is 900mmol/L. A 400W high-pressure mercury lamp is placed inside a quartz photoreactor with a hollow interlayer, and circulating water is passed into the interlayer, and the entire reactor is placed in a water tank filled with water to cool the light source. Add 4ml of methanol solution containing 250mmol/L propylene oxide, 12mmol/L catalyst cobalt acetate and cadmium iodide, and 900mmol/L sodium acetate into the quartz test tube, and attach the quartz test tube to the outer wall of the photoreactor. At room temperature, directly add 625mmol/L methyl formate to the above mixed solution at one time, simultaneously turn on the high-pressure mercury lamp to irradiate the reaction solution for 45 hours, and control the reaction temperature at 25-60°C. The obtained product was analyzed by gas chromatography with n-decane as an internal standard, and the results measured by gas chromatography were shown in Figure 5, and the calculated yield was 55%. The product was identified by gas chromatography-mass spectrometry, see accompanying drawing 6, and it was determined to be methyl β-hydroxybutyrate.

Claims (1)

1. a method for synthesizing methyl β-hydroxybutyrate, is characterized in that: at room temperature, to containing 250～1000mmol/L propylene oxide and 8～16mmol/L cobalt acetate and cadmium iodide catalyst and 300～900mmol Add 125-625mmol/L methyl formate directly to the methanol solution of /L sodium acetate at one time. hours, the reaction temperature is 25-60°C.

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