Method for preparing pyruvic aldehyde dimethyl acetal
A technology of acetaldehyde dimethyl acetal and propylene glycol is applied in the field of compound preparation, which can solve the problems of excessive waste liquid, environmental pollution, and low product purity, and achieve the effects of reducing pollution, improving product quality, and improving yield.
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Embodiment 1
[0029] Methylglyoxal monohydrate embodiment: select a reactor with an inner diameter of 10mm and a length of 350mm, in which the constant temperature section is 55mm. Catalyst can choose Zn 2+ 、Ce 4+ , Pb 4+ 、Pr 3+ , La 3+ 、K + , ZrO 2 , α-Al 2 o 3 、Cu + , SiO 2 、H 3 PO 4 , (NH 4 )H 2 PO 4 , AgNO 3 It is obtained by modifying electrolytic silver, the dose is 3mL, and it is placed in a constant temperature section; the upper and lower parts are filled with quartz sand, and the reaction product is condensed in one stage to obtain aceglyoxal monohydrate, and the tail gas is then absorbed in multiple stages. The experimental device is entirely made of stainless steel. 1,2-propanediol is injected by a double plunger pump, water vapor is provided by a boiler and measured by a flow meter, and air and nitrogen are compressed air that is supplied by a steel cylinder after being measured by a flow meter. The optimum conditions for synthesis are: reaction temperature 350...
Embodiment 2
[0031] Add 100 grams of methylglyoxal monohydrate in a 1000ml three-necked flask equipped with a mechanical stirring device, a reflux condenser, and a thermometer. 3 COCHO.H 2 O meter 90%, 320.4 grams of industrial grade methanol, 40 grams of modified resin catalyst, vigorously stirred, heated and refluxed for 16 hours; cooled to room temperature, filtered, and filtered out the modified resin catalyst; the filtrate was injected into 1000ml equipped with a mechanical stirring device and a thermometer Distill in a three-necked flask with a distillation head with a controllable reflux ratio to distill off low boiling substances such as methylal and methyl acetate until the top temperature reaches 64°C; then recover methanol under the condition of variable reflux ratio to maintain the top Warm at 64~66°C until the temperature in the flask reaches 90°C; add water vapor to the lower part of the flask to continue distillation, and collect the crude acetoaldehyde dimethyl acetal solut...
Embodiment 3
[0033] Add 100 grams of methylglyoxal monohydrate (in CH 3 COCHO.H 2 (90% in O)), the front cut when refining in embodiment one, the raffinate after steam distillation, the front cut and raffinate when refining, the methyl alcohol that reclaims and fresh technical grade methanol total 320.4 grams, modified resin catalyst ( Recycling) 40 grams, stirred vigorously, heated to reflux for 16 hours; cooled to room temperature, filtered, and filtered out the modified resin catalyst; the filtrate was injected into a three-necked flask equipped with a mechanical stirring device, a thermometer and a distillation head with a controllable reflux ratio. Carry out distillation, distill out methylal, methyl acetate and other low boilers, until the top temperature reaches 64°C; then recover methanol under the condition of variable reflux ratio, maintain the top temperature at 64~66°C, until the temperature in the flask reaches 90 ℃; in the lower part of the flask, water vapor was introduced ...
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