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A production method, metaldehyde technology, applied in the direction of organic chemistry, can solve the problems of high energy consumption and low product yield, and achieve the effects of less dosage, short reaction time and mild reaction conditions
Inactive Publication Date: 2011-10-05
DALIAN UNIV OF TECH
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Embodiment 1
[0028] Acetaldehyde (25mL) was cooled to 0°C, 2mL ether and 0.5mL pyridine were added, the temperature of the mixture was lowered to -15°C, and 0.4mL thionyl chloride (SOCl 2 ), control the catalyst addition rate, and ensure that the temperature of the reaction mixture does not exceed 0°C. After the catalyst is added, stir vigorously at -15°C for 30 minutes, then filter, wash the solid with 20mL of ether, and dry it in vacuum to obtain a white crystal Metaldehyde 1.88g, yield 9.6%. Gas chromatography test results are attached figure 1 , peak time: 8.283min, 15.094min Area% 15.131, 84.869.
Embodiment 2
[0030] Acetaldehyde (25mL) was cooled to 0°C, 2mL of ether and 0.4mL of pyridine were added, the temperature of the mixture was lowered to -15°C, and 0.4mL of phosphine pentachloride (PCl 5 ), control the catalyst addition rate, and ensure that the temperature of the reaction mixture does not exceed 0°C. After the catalyst is added, stir vigorously at -15°C for 30 minutes, then filter, wash the solid with 20mL of ether, and dry it in vacuum to obtain a white crystal Metaldehyde 0.9g, yield 4.6%. Gas chromatography test results are attached figure 2 , peak time: 8.292min, 15.112 min Area%, 79.112, 20.878.
Embodiment 3
[0032] Acetaldehyde (25mL) was cooled to 0°C, 2mL ether and 0.4mL pyridine were added, the temperature of the mixture was lowered to -15°C, and 0.4mL sulfuryl chloride (SO 2 Cl 2 ), control the catalyst addition rate, and ensure that the temperature of the reaction mixture does not exceed 0°C. After the catalyst is added, stir vigorously at -5°C for 30 minutes, then filter, wash the solid with 20mL ether, and vacuum dry to obtain a white crystal Metaldehyde 1.48g, yield 7.6%. Gas chromatography test results are attached image 3 , peak time: 8.292min, 15.108 min Area%, 16.250, 83.750.
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Abstract
The invention discloses a method for producing metaldehyde, which comprises polymerization of aldehyde under an acidic condition, and is characterized in that: in polymerization, a compound of a general formula XpOnYm is used as a catalyst; in the formula, X may be S, C or P; Y may be F, Cl, Br, I or CN; P may be 1 or 2; n may be 0, 1 or 2; and m is an integer ranging from 1 to 5. Compared with the prior art, the method has the advantages that: a precursor of an acidic catalyst is used as a catalyst; the acidic catalyst is gradually released in a reaction process; and the catalyst is efficient and the reaction time is shorter. In addition, the catalyst used in the invention is cheap and readily available, the use amount is small, the yield of the metaldehyde is improved effectively to 10.2 percent which is higher than the yield that is 6 percent in modern industry; meanwhile, the reaction time is reduced by at least 3 to 10 hours to 30 to 90 minutes from the original reaction time, and thus, the energy consumption for keeping low-temperature environment is reduced greatly. Meanwhile, the method disclosed by the invention is mild in reaction conditions, and the industrialization can be realized easily.
Description
technical field [0001] The invention relates to a method for synthesizing metaldehyde by taking acetaldehyde as a raw material through a polymerization reaction under acidic conditions, and particularly relates to a catalyst therein. 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. Metaldehyde is usually prepared by acetaldehyde polymerization, but in the prior art, more of its trimerization products are obtained in the reaction process. Due to its harsh reaction conditions, it needs to be produced in a low temperature environment and the reaction time is long, and the depolymerization of the by-product para...
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