CN1609089A - A kind of catalytic synthesis method of methyl succinic acid - Google Patents

Abstract

The present invention is catalytic synthesis process of methyl succinic acid. The present invention adopts Pd/C catalyst and itaconic acid as material to synthesize methyl succinic acid through liquid phase hydrogenation in certain mixed solvent. The reaction is completed at 10-80 deg.c; and the coarse product is purified through re-crystallization inside cold ethyl ether to reach methyl succinic acid content over 99 %. The said preparation process has mild reaction condition, short reaction time, high itaconic acid conversion rate of 98-99 % and high selectivity of 99 %.

Description

A kind of catalytic synthesis method of methyl succinic acid

technical field

The invention relates to the field of chemistry and chemical engineering, in particular to a synthesis method of methylsuccinic acid.

Background technique

The molecular formula of methylsuccinic acid is C ₅ H ₈ O ₄ , and the English name is methylsuccnic acid. It is a chiral compound (CA registration number is [498-21-5], (+-)[630-60-2], R [3641-51-8], S[2174-58-5]), white prismatic crystal, widely used, generally used, waste paper bleaching, etchant, esterification reaction, photochemical reaction, chiral molecule is widely used , is an indispensable reagent for the synthesis of a large number of chiral compounds and pharmaceutical macromolecules.

There are many methods for synthesizing methylsuccinic acid in the existing literature, which can be roughly divided into two categories: chiral synthesis and achiral synthesis.

There are two routes for chiral synthesis. One is that Mateoli, Tefort, Dawson et al. use itaconic acid as a raw material, and use Rh, Ru, Pd and other metal complexes in the presence of special complexes with group VIII elements as central atoms. Mol catalyst, asymmetric hydrogenation synthesis (Journal of Mol Catalyst A: Chem.1996, 109 (1), CA 125 166884r, Synthesis 1992 (10), 951-3, CA 118 38537y, Tetrahedron: Asymmetry 1995, 6 (10 ), 2535-46, CA 124116988m), or Tsubokura, Akira et al. Enzyme-catalyzed synthesis (EP 481,712, CA 117 46739k, Chemical letters 1992(5), 785-6, CA 117 25906x). Another kind, exactly Mizoguchi, Akio etc. use achiral methylsuccinic acid, dissolve in chiral solvent and react to make chiral methylsuccinic acid (JP 0789,897[9889,897], CA 123 143292r. JP 06100,430 [94 100,430], CA 121 230337m). The chiral method has low yield, complicated preparation and separation process, and high cost due to the use of chiral solvents.

There are many achiral synthesis methods, such as the oxidation method of Saito, Hidekazu et al. (JP 08 81,410[96 81,410], CA 125 33177r,) the yield of the oxidation method is not higher than 59%, and the reaction is high temperature and high pressure, (130°C , 5atm), it takes a long time (60h). There is also the ester hydrolysis method of Saito, Hidekazu et al. (JP 07,258,149 [95 258,149], CA 124 145443k). The process of ester hydrolysis is complex, with many operation steps, high cost and low yield.

Contents of the invention

The purpose of the present invention is to obtain a kind of preparation method is simple and convenient, and reaction condition is gentle, and yield is high, and cost is low, the catalytic synthesis method of methyl succinic acid.

The invention uses itaconic acid (ie, methylene succinic acid) as a raw material, palladium carbon (Pd/C) as a catalyst, and uses a mixed solvent of ethanol and tetrahydrofuran to react with stirring, and liquid-phase hydrogenation to synthesize methyl succinic acid. Really efficiently synthesize products from raw materials in one step,

The invention uses diethyl ether as a solvent to recrystallize the methyl succinic acid containing itaconic acid, thereby purifying simply and efficiently to obtain the methyl succinic acid with a content of 99%.

The present invention is carried out in a batch-type still-type reactor, first put palladium-carbon catalyst and raw material itaconic acid, add mixed solvent ethanol and tetrahydrofuran, after dissolving, put into batch-type still-type reactor, leak detection, ventilation, stirring, constant temperature , hydrogenation reaction. After the reaction is basically completed, settle, filter, distill under reduced pressure, and dry. get the product.

Concrete preparation condition of the present invention is:

<1>The reaction temperature is 10-80°C, the reaction pressure is 1.0-10atm, and the reaction time is 2 hours-16 hours;

<2>The mass ratio of reaction feed is palladium carbon catalyst: itaconic acid=0.015-2;

<3> the palladium content of palladium carbon catalyst is 0.1%-10wt%;

<4> The mixed solvent is ethanol and tetrahydrofuran, and the volume ratio of ethanol and tetrahydrofuran is 0-4.

In the above reaction conditions, the temperature is low, the reaction time can be slightly longer, and the pressure is higher. On the contrary, the reaction time and pressure are relatively low, which can be properly selected according to the conditions.

In the above conditions, although the mixed solvent can be a single tetrahydrofuran solvent, it is not as good as the mixed solvent in terms of high conversion rate and high selectivity.

The better reaction conditions of the present invention are as follows:

The reaction temperature is 20-40°C;

Reaction time 2-10 hours;

Reaction pressure 1.0-5.0 atmosphere;

The solvent ratio of ethanol and tetrahydrofuran is 0-1;

The reaction feed mass ratio is palladium carbon catalyst:itaconic acid=0.025-1.5.

After the reaction, the crude product can be purified by recrystallization with cold diethyl ether, i.e. unheated diethyl ether, so that the content of methyl succinic acid can reach more than 99%, which is a good way to separate itaconic acid and methyl succinic acid. acid treatment. Recrystallization is also unnecessary, and the product quality can meet industrial needs.

The catalyst used in the invention can be reused 5-7 times, which reduces the reaction cost.

The crude product was dissolved in cold ether for recrystallization, and after filtration, the filtrate was poured into the solvent, and after the ether was volatilized, a product with higher purity was left.

The reaction formula of the present invention is as follows:

The selection of the mixed solvent of the present invention is very important. The mixture of ethanol and tetrahydrofuran is a better mixed solvent. Under the mixing ratio of the present invention, there is satisfactory conversion rate and selectivity.

Cold diethyl ether is used as a solvent for recrystallization. The structure of the raw material and the product are very similar, and it is difficult to separate them with general solvents. Even if diethyl ether is used, the temperature is different, and the result is also different.

The purity of the product obtained in the present invention is more than 99.5%, and the product is tested by IR and NMR hydrogen spectrum and carbon spectrum, and the results are shown in the figure.

The method of the invention has mild and easy reaction conditions, uses a suitable solvent, is simple to operate, and takes less time. Compared with the traditional method, the conversion rate and selectivity of the one-step reaction are very high; both of them can reach more than 99%, which has great advantages. In addition, the catalytic stability of Pd/C is very strong, and the conversion rate and selectivity of the product used continuously for more than 3 times are >99%. The recrystallization method used in the present invention is simple and has few steps. The recrystallized product has high purity.

Description of drawings

Fig. 1 is the IR spectrogram of the product of the present invention, and the instrument used for FT-IR uses the NEXUS 470 infrared spectrometer 4000cm ^- 1-400cm ^-1 of NICOLET Company of the United States to analyze the tablet and use KBr.

Fig. 2 is the NMR hydrogen spectrogram of the product of the present invention, the instrument used for NMR is a DMX 500 nuclear magnetic resonance instrument, and the reference substance is CDCl ₃ .

Fig. 3 is the NMR mass spectrogram of the product of the present invention, the instrument used for NMR is a DMX 500 nuclear magnetic resonance instrument, and the reference substance is CDCl ₃ .

Detailed ways

Embodiment: 1 is carried out in long 13 centimeters, the intermittent tank reactor of diameter 3.8 centimetres, puts into palladium carbon catalyst (palladium content 5wt%) 1.0g and 10g raw material itaconic acid, adds mixed solvent 10ml ethanol and 50ml THF, After dissolving, check for leaks, pass hydrogen gas, stir, keep constant temperature at 50°C and constant pressure at 2.5atm for hydrogenation reaction. The reaction was almost complete after 12 hours. Sedimentation, filtration, vacuum distillation, drying. The obtained product has a conversion rate of 99.15% and a selectivity of 99.95%.

Embodiment: 2 same reaction apparatus, with 18g palladium-carbon catalyst (w0.25%) 10g raw material, mixed solvent ratio is 0ml ethanol/60ml tetrahydrofuran, 10 ℃, 1.0atm, reacted 16 hours, obtained product transformation rate 99.83%, The selectivity is 99.67%.

Embodiment: 3 same as above reaction apparatus, with 0.15g (w10%) catalyst 10g raw material, mixed solvent ratio is 48ml ethanol/12ml tetrahydrofuran, 80 ℃, 9.5atm, reaction 2 hours, obtain product transformation rate 99.83%, selectivity is 99.90%.

Embodiment: 4 same reaction apparatus, with 1.0g palladium carbon catalyst (w5%) 10g raw material, mixed solvent ratio is 20ml ethanol/40ml tetrahydrofuran, 50 ℃, 2.5atm, reaction 12 hours, reuse catalyst reaction three times, obtain product as 1) The conversion rate is 99.83%, and the selectivity is 99.67%. 2) The conversion rate is 99.72%, and the selectivity is 99.53%. 3) The conversion rate is 99.62%, and the selectivity is 99.73%.

Example: 5 0.7 g of the crude product with a content of 85% was purified by recrystallization with 5 ml of cold diethyl ether, the residue was 0.135 g, and the collected product was 0.40 g with a content of 98%.

Example: 6 0.6 g of the crude product with a content of 98% was purified by recrystallization with 5 ml of cold diethyl ether, the residue was 0.095 g, and the collected product was 0.50 g with a content of 99%.

Claims (8)

1. the process for catalytic synthesis of pyrovinic acid under the normal temperature is characterized in that adopting palladium-carbon catalyst, is raw material with methylene-succinic acid, and by certain mixed solvent liquid-phase hydrogenatin stirring reaction synthesizing methyl Succinic Acid, concrete preparation condition is:

＜1〉temperature of reaction 10-80 ℃, reaction pressure 1.0-10atm, the reaction times is 2 hours-16 hours;

＜2〉reacting the mass ratio that feeds intake is palladium-carbon catalyst/methylene-succinic acid=0.015-2;

＜3〉the palladium content of palladium-carbon catalyst is 0.1-10wt%;

＜4〉mixed solvent is ethanol and tetrahydrofuran (THF), and ethanol and tetrahydrofuran (THF) volume ratio are 0-4.

2. the process for catalytic synthesis of pyrovinic acid under the normal temperature according to claim 1, the catalytic synthesis temperature that it is characterized in that pyrovinic acid is 20--50 ℃.

3. the process for catalytic synthesis of pyrovinic acid under the normal temperature according to claim 1, the catalytic synthesis time that it is characterized in that pyrovinic acid is 2-10 hour.

4. the process for catalytic synthesis of pyrovinic acid under the normal temperature according to claim 1, the catalytic synthesis pressure that it is characterized in that pyrovinic acid is the 1-5.0 normal atmosphere

5. the process for catalytic synthesis of pyrovinic acid under the normal temperature according to claim 1 is characterized in that the synthetic use of the catalysis mixed solvent of pyrovinic acid is ethanol and tetrahydrofuran (THF), and volume ratio is 0-1.

6. the process for catalytic synthesis of pyrovinic acid under the normal temperature according to claim 1 is characterized in that reacting the mass ratio that feeds intake is palladium-carbon catalyst: methylene-succinic acid=0.025-1.5.

7. the process for catalytic synthesis of pyrovinic acid under the normal temperature according to claim 1 is characterized in that the aftertreatment of reaction use cold diethyl ether recrystallization.

8. the process for catalytic synthesis of pyrovinic acid under the normal temperature according to claim 1 is characterized in that palladium-carbon catalyst repeated use 5-7 time.

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