Patent ID: 9212162
Filing Date: 2015-12-15
Classification: C07D

Abstract:
1. A process for the preparation of a Form II crystalline polymorph of imidacloprid exhibiting an X-ray powder diffraction pattern having characteristic peaks (expressed in degrees 2θ+/−0.2°θ) at one or more of the following positions: 4.580, 13.780, 18.420, 18.880 and 23.120, or exhibiting a Differential Scanning calorimetry (DSC) thermogram which is characterized by a predominant endotherm peak at about 136.5° C., or both, comprising: (i) dissolving imidacloprid in an amount of non-aqueous solvent or mixture of non-aqueous solvents appropriate to obtain a non-aqueous solution, wherein the non-aqueous solvent is selected from the group consisting of methanol, ethanol, tetrahydrofuran, acetonitrile, methylene chloride, isopropyl alcohol, acetone, N,N-dimethyl-formamide, dimethyl sulfoxide, toluene, benzene, n-hexane, petroleum ether, ethyl acetate, ether, dichloromethane, chloroform, and carbon tetrachloride; (ii) cooling the solution rapidly, thereby forming crystals of polymorph Form II of imidacloprid; (iii) isolating the crystals.