Preparation method of efficient cypermethrin

Abstract

The invention discloses a preparation method of efficient cypermethrin. The method comprises the following steps of: dissolving cypermethrin crude oil into alkane, slowly heating to 40-50 DEG C, and fully mixing to form a uniform phase; filtering undissolved substances out, and cooling to the room temperature; adding a guanidine compound while stirring at the temperature of 14-16 DEG C, adding a small amount of efficient cypermethrin solid crystal, reacting at the same temperature for 18-30 hours, gradually cooling to 12-14 DEG C, and preserving heat for reacting for 18-30 hours; cooling to 10-20 DEG C, and preserving heat for 38-58 hours; adding an alkane solvent, cooling to 4-6 DEG C, and preserving heat for 20-28 hours; and sampling and analyzing to determine that the transformation rate of epimerization is 95 percent, slowly adding the acid water of which the pH is 1-2 into a material which is subjected to epimerization while stirring, testing whether the pH is less than 4, removing a water layer, washing to neutral, stirring, and standing for delaminating to obtain an efficient mother liquid. Due to the adoption of the preparation method, inactive isomers in cypermethrin crude oil can be transformed into high-activity isomers, the transformation rate is up 95 percent, and the displacement yield is over 98 percent.

Description

[0001] technical field [0002] The invention relates to a preparation method of an agricultural insecticide, in particular to a preparation method of beta-cypermethrin. Background technique [0003] Commonly synthesized pesticides are usually a mixture of cis-trans isomers or left-handed and right-handed isomers, which are usually prepared through epimeric separation of cis-trans isomers, physical and chemical resolution or directional synthesis of left-handed isomers Highly effective stereoisomeric pesticide. Since the epimerization mechanism is the same as the isomerization mechanism of optical (and geometric) isomers of organic compounds under the action of basic or acidic catalysts, under the action of a base (or acid) of appropriate strength, substituting vinyl cyclopropane Carboxylate esters are prone to configuration changes because the carbon atom connected to the cyano group at the alcohol position is more active. Relatively speaking, the asymmetric carbon atom on...

AI Technical Summary

Problems solved by technology

These low-efficiency or ineffective ingredients not only cannot effectively control pests and diseases, but also increase the amount of chemicals used, pollute the environment, and increase drug residues in agricultural products