Method for preparing diethoxymethane by using active carbon supported solid acid catalyst

Abstract

The invention relates to a method for preparing diethoxymethane by using an active carbon supported solid acid catalyst. The method is characterized in that formaldehyde and ethanol are used as raw materials and reacted under normal pressure under the action of a solid acid catalyst at the temperature of 70 to 100 DEG C, the reflux ratio is controlled to be 1:1-4:1, distillate of 74 to 76 DEG C is collected on the top of a tower, and the diethoxymethane product is obtained; after the aqueous solution in a tower kettle is filtered, the solid acid catalyst is recycled in the kettle; the molar ratio of the formaldehyde to the ethanol is 1:2-1:5, the formaldehyde raw material is a formaldehyde solution at the concentration of over 37 weight percent, and the ethanol raw material is absolute ethanol or an ethanol solution at the concentration of 75-95 weight percent; the solid acid catalyst is the active carbon supported solid acid catalyst, the active acid ingredient is sulfuric acid, and the acid solid capacity is 15 to 25 mass percent; and the consumption of the solid acid catalyst is 0.3 to 10 percent of the total mass of the reactants. The method has the advantages that the catalyst is economic in preparation, easy to separate from the product and low in equipment corrosion, and the waste catalyst is easy and convenient to reclaim and treat.

Description

technical field [0001] The invention relates to a method for preparing diethoxymethane by an activated carbon-supported acid catalyst; diethoxymethane is also called formaldehyde diethyl acetal, and the structural formula is: CH 3 CH 2 OCH 2 O CH 2 CH 3 ; belongs to the technical field of organic chemical industry. Background technique [0002] Diethoxymethane, is a colorless transparent liquid, the molecular formula is C 5 H 12 O 2 , the molecular weight is 104.15, the pure product has a boiling point of 88 °C, a melting point of -66.50 °C, and a solubility of 9% (wt) in water at 20 °C. It has good properties and can be used in organic synthesis and extraction, dilution, recrystallization and other solvents. [0003] As a solvent in organic synthesis, diethoxymethane is an aprotic solvent with low affinity for water, insoluble in water and non-hygroscopic, so it can be directly used in some water-repellent compounds without further drying. Sensitive reactions such...

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Problems solved by technology

[0007] Dimethyl sulfoxide is unstable to acid, and it will be decomposed by heating to generate formaldehyde, which will undergo addition reaction with ethanol to obtain diethoxymethane, which will produce SO as a by-product. 2 , which pollutes the environment and thus is not conducive to large-scale production

The classic aldol condensation reaction uses mineral acids (such as H 2 SO 4 , HF, H 3 PO 4 , p-toluenesulfonic acid, etc.) and Lewis acids (such as A1C1 3 , FeC1 3 etc.) catalysts, all have good catalytic activity, but there are disadvantages such as difficulty in separation and recovery, serious corrosion to equipment, etc.