Synthesis method of metaldehyde

A synthetic method, metaldehyde technology, applied in the direction of organic chemistry, etc., can solve the problems of high acidity in the reaction environment, corrosive equipment, high cost consumption, etc., to simplify the synthesis process and operation steps, save time and cost, and achieve high efficiency. The effect of production

Inactive Publication Date: 2019-04-12
JIANGSU NOON CROP SCI CO LTD
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

) under the effect of reaction to generate metaldehyde, yield 6-10%, this process needs to be carried out at a lower temperature, resulting in high energy consumption, and the reactio

Method used

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  • Synthesis method of metaldehyde
  • Synthesis method of metaldehyde
  • Synthesis method of metaldehyde

Examples

Experimental program
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Effect test

Embodiment 1

[0017] Put 50kg of acetaldehyde and 2.5kg of ether into the fixed-bed reactor filled with heterogeneous solid heteropolyacid-loaded cesium carbonate catalyst and the carrier as Mg-based SiO2, cool to -15°C, start the reaction, and control the temperature during the reaction At -10°C, filter after the reaction, wash the solid with water, and dry to obtain metaldehyde with a content of 99.1% and a yield of 9.1%. The filtrate is distilled, and sulfuric acid is added as a catalyst, the paraldehyde in the filtrate is depolymerized, acetaldehyde and ether are distilled and separated, and the next feeding is used for later use.

Embodiment 2

[0019] Put 20kg of acetaldehyde and 1kg of ether into the fixed-bed reactor filled with heterogeneous solid heteropolyacid-loaded catalyst tungstophosphoric acid, and the carrier is Mg-based SiO2, and cool to -10°C to start the reaction. During the reaction, the temperature is controlled at -5°C, filter after the reaction, wash the solid with water, and dry to obtain metaldehyde with a content of 98.8% and a yield of 12.0%. The filtrate is distilled, and sulfuric acid is added as a catalyst, the paraldehyde in the filtrate is depolymerized, acetaldehyde and ether are distilled and separated, and the next feeding is used for later use.

Embodiment 3

[0021] Put 40kg of acetaldehyde and 2kg of ether into the fixed-bed reactor filled with heterogeneous solid heteropolyacid-loaded catalyst tungstophosphoric acid, and the carrier is Mg-based SiO2, and cool to -5°C to start the reaction. During the reaction, the temperature is controlled at 0°C, filter after the reaction, wash the solid with water, and dry to obtain metaldehyde with a content of 99.2% and a yield of 11.0%. The filtrate is distilled, and sulfuric acid is added as a catalyst, the paraldehyde in the filtrate is depolymerized, acetaldehyde and ether are distilled and separated, and the next feeding is used for later use.

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Abstract

The invention belongs to the field of organic synthesis, and particularly discloses a synthesis method of metaldehyde. The synthesis method comprises the following steps: S1, preparing 1-100 kg of acetaldehyde and 0.05-5 kg of diethyl ether, and adding the diethyl ether into the acetaldehyde; S2, carrying out cooling, then carrying out a reaction by using a heterogeneous solid heteropolyacid loaded catalyst fixed bed, carrying out filtering, washing the obtained solid with water, and carrying out drying to obtain a white crystalline metaldehyde product; and S3, distilling the filtrate, addingsulfuric acid as a catalyst, and separating out acetaldehyde and diethyl ether by distilling for feeding in a next time. According to the synthesis method, the reaction conditions are mild, the cost is low, and the problems of long reaction time, harsh reaction conditions and many side reactions in an old process are solved, so that the process is stable, the yield is high, operation is simple, cost is low, environment protection and safety are achieved, continuous and efficient production is realized, and industrial scale production is facilitated.

Description

technical field [0001] The invention relates to the technical field of organic synthesis, in particular to a method for synthesizing metaldehyde. Background technique [0002] Metaldehyde is a white needle-like crystal with high combustion temperature, stable flame, non-volatile, insoluble in water, etc. It is known as solid alcohol and can be used to make firecrackers, fireworks, colored candles, and can replace silver iodide as The rainfall agent can also be used to kill snails, slugs and other lung mollusc pests and snails parasitized by blood-sucking worms. [0003] Metaldehyde is usually prepared by polymerization of acetaldehyde. In 1947, the US patent introduced the use of hydrobromic acid-pyridine as a catalyst to form metaldehyde by polymerization of acetaldehyde at a low temperature of -20°C, with a yield of 10-12%; In 1986, a German patent introduced that dry hydrogen chloride gas was used as a catalyst to prepare metaldehyde by adding acetaldehyde in batches at ...

Claims

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Application Information

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IPC IPC(8): C07D323/00
CPCC07D323/00
Inventor 孟宪锋
Owner JIANGSU NOON CROP SCI CO LTD
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