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Diethyl Methylmalonic acid (MDEA) is an organic compound used in industrial chemistry. It is a transparent and colorless liquid with good stability, corrosion resistance and solubility. MDEA is applied in the fields of polyester, plastic, and pigment synthesis, and is an important organic synthesis raw material. Below, we will provide a detailed introduction to the production process of MDEA.

Step 1: Synthesis of MDEA raw material - propylene alcohol

The preparation process of MDEA requires the use of raw materials such as propylene alcohol and acetic acid, and propylene alcohol is the starting material for synthesizing MDEA. The preparation method is as follows.

Propylene alcohol is produced through the oxidation reaction of ethylene gas. Ethylene is heated to 250 ° C in air through a catalyst and mixed with air for reaction. The resulting mixture is further hydrated in a thermal reactor to obtain propylene alcohol. The chemical reaction formula for this process is as follows:

C2H4+ ½ O2 → C2H4O

C2H4O+H2O → C3H6O

Step 2: Hydrogenation to convert acetaldehyde

The synthesis of MDEA requires the use of acetaldehyde as one of the reactants. However, acetaldehyde cannot directly react with MDEA under weak acid conditions. Therefore, acetaldehyde is first converted into alcohol and then used for the synthesis of MDEA.

Acetaldehyde is converted into ethanol through hydrogenation reaction. This can be achieved by simultaneously heating and applying high pressure, adding hydrogen gas and catalyst to the reaction liquid for hydrogenation reaction. The chemical reaction formula is as follows:

C2H4O+2H2 → C2H6O

Step 3: Prepare MDEA with ethanol

Ethanol obtained through the second step of hydrogenation reaction is one of the raw materials for the reaction of MDEA. At this time, the reactants used are ethanol and Methylmalonic acid, and the reaction process is as follows:

① CH3CH (OH) CH3+HOOC (CH2) 2COOH → CH3C (H) (COOC2H5) 2+H2O

② CH3C (H) (COOC2H5) 2+CH3OH → CH3C (H) (COOCH3) 2+C2H5OH

In the reaction, Methylmalonic acid reacts with ethanol to generate methyl acetate and MDEA. In this reaction, methyl ester is used as one of the reactants, which allows for higher yields in incomplete reactions. Further thermal decomposition can be used to achieve the desired yield of the target product.

Step 4: Distillation purification of MDEA

When MDEA is synthesized and formed, it needs to be purified by distillation to remove any impurities and residual reactants, while obtaining a high-purity product. The distillation process of MDEA includes heating the primary synthetic product to high temperature, sublimating it and entering the recovery tank, and separating and removing impurities through cooling and solidification in the sublimation and condensation stages. This step can be carried out by Vacuum distillation, molecular sieve separation or activated carbon separation.

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