3401-80-7Relevant articles and documents
Hybrid catalytic effects of K2CO3 on the synthesis of salicylic acid from carboxylation of phenol with CO2
Gu, Miaofei,Yan, Xingxing,Cheng, Zhenmin
, p. 391 - 406 (2016)
As a base-promoted Kolbe-Schmitt carboxylation reaction, the mechanism of synthesis of salicylic acid derivatives from phenols with CO2 in the industry is still unclear, even up to now. In this paper, synthesis of 3,6-dichloro salicylic acid (3,6-DCSA) from 2,5-dichloro phenoxide and CO2 was investigated in the presence of K2CO3. We show the reaction can proceed by itself, but it goes at a slower rate as well as a lower yield, compared to the case with the addition of K2CO3. However, the yield of 3,6-DCSA is only minorly affected by the size of K2CO3, which cannot be explained from the view of catalytic effect. Therefore, K2CO3 may on one hand act as a catalyst for the activation of CO2 so that the reaction can be accelerated, while on the other hand, it also acts as a co-reactant in deprotonating the phenol formed by the side reaction to phenoxide, which is further converted to salicylate.
Synthesis method of 3,6-dichlorosalicylic acid
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, (2019/06/05)
The invention provides a synthesis method of 3,6-dichlorosalicylic acid. The synthesis method comprises the following steps: S1, brominating o-cresol to obtain 2-methyl-4-bromophenol; S2, chlorinating2-methyl-4-bromophenol to obtain 2-methyl-3,6-dichloro-4-bromophenol; S3, oxidizing 2-methyl-3,6-dichloro-4-bromophenol to obtain 3,6-dichloro-4-bromosalicylic acid; S4, debrominating 3,6-dichloro-4-bromosalicylic acid to obtain 3,6-dichlorosalicylic acid. In the synthesis route, the raw materials are easily available and the comprehensive cost is low. The preparation process comprises directional bromination and directional chlorination, selectivity is high, product quality is stable, and total yield is high. Besides, the preparation process of 3,6-dichlorosalicylic acid is simple, and industrial implementation is facilitated.
Continuous production processes of dicamba methyl ester and dicamba methyl ester emulsifiable concentrate
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, (2019/06/05)
The invention provides a continuous production process of dicamba methyl ester. The process comprises the following steps: A) 5-bromo-3,6-dichlorosalicylic acid is subjected to a reaction under an alkaline condition and under the action of metal powder to remove bromine atoms in para-positions of hydroxyl, and 3,6-dichlorosalicylic acid is obtained; B) 3,6-dichlorosalycylic acid and halomethane are subjected to an etherification reaction in a mixed solvent of water and methanol, and methyl 3,6-dichloro-2-methoxybenzoate is obtained; C) methanol is removed by distillation; D) a system after distillation is left to stand for laying, an organic phase is distilled, and dicamba methyl ester is obtained. By means of the preparation process, continuous production can be realized, workers are notrequired to make direct contact with materials, the control degree is high, the production operation environment is greatly improved and safer, the process route and equipment are simple, the production cost is low, besides, the product yield and purity are greatly improved, and a superior route suitable for mass industrial production is provided.
Preparation method of micamba methyl ester
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, (2019/06/13)
The invention provides a preparation method of micamba methyl ester. The preparation method comprises the steps as follows: A) salicylic acid and bromine are subjected to a reaction in concentrated sulfuric acid, 5-bromosalicylic acid is obtained; B) 5-bromosalicylic acid and chlorine are subjected to a chlorination reaction, 5-bromo-3,6-dichlorosalycylic acid is obtained; C) 5-bromo-3,6-dichlorosalycylic acid is subjected to a debromination reaction under the alkaline condition and under the action of metal powder, and 3,6-dichlorosalycylate is obtained; D) 3,6-dichlorosalycylate and halomethane are subjected to a methylation reaction in methanol and a quaternary ammonium salt phase transfer catalyst, and 3,6-dichloro-2-methyl methoxybenzoate is obtained; E) methanol is removed by distillation; F) a system after distillation is left to stand for laying, an organic phase is distilled, and dicamba methyl ester is obtained. By means of the preparation method, the yield and purity are higher, the route is simple and the production cost is low.
