Polymorphs and amorphous forms of 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl]-1H-pyrazole-3-carbonitrile
The present invention relates to novel crystalline polymorphs, solvate pseudomorphs and amorphous form of 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl]-1H-pyrazole-3-carbonitrile (fipronil). The present invention also provides methods for preparing the novel polymorphs, pseudomorphs and amorphous form, as well as insecticidal or pesticidal compositions comprising same, and methods of use thereof as pesticidal agents.
1. A crystalline form of 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoro-methyl)sulfinyl]-1H-pyrazole-3-carbonitrile which is polymorph Form II exhibiting at least one of the following properties:
(a) an X-ray powder diffraction pattern having characteristic peaks expressed in degrees 2° θ (+/−0.20° θ) at about 14.4, 15.7, 16.75, 17.2, 19, 20.7, 22.95, 23.55, and 32.15;
(b) an infrared (IR) spectrum at the 3000 cm −1 , having characteristic peaks at about 3344 and 3436.5 cm −1 ;
(c) a Differential Scanning calorimeter (DSC) thermogram having a single predominant endotherm at about 195° C. as measured by a Differential Scanning calorimeter (DSC) at a scan rate of 2° C. and/or 10° C. per minute.
2. Crystalline polymorph Form II according to claim 1 , wherein
the x-ray powder diffraction attern is substantially as shown in FIG. 4 ;
the IR spectrum is substantially as shown in FIG. 5 ; and
the DSC is substantially as shown in FIG. 6 .
3. The crystalline polymorph Form II according to claim 1 , wherein the x-ray diffraction pattern has characteristic peaks expressed in degrees 2° θ (+/−0.20° θ) at about 11.7, 14.4, 15.7, 16.75, 17.2, 18.2, 19, 20.7, 22.95, 23.55, 24.0, and 32.15.
4. A process for the preparation of the crystalline polymorph Form II of claim 1 , the process comprising the steps of crystallizing said compound from a solvent selected from the group consisting of isopropyl alcohol, hexane, ethyl acetate, 1-propanol, butanol and methyl isobutyl ketone (MIBK), and any mixture of said solvents; and isolating the resulting crystals.
5. The process according to claim 4 , comprising the steps of:
(a) preparing a solution of 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl]-1H-pyrazole-3-carbonitrile in said solvent or mixture of solvents;
(b) cooling the solution so as to form crystals of said compound; and
(c) isolating the crystals.
6. The process according to claim 5 , wherein step (a) is conducted with heat.
7. The process according to claim 5 , wherein the solution obtained after step (a) is cooled to a temperature of about 0° C. to about room temperature.
8. The process according to claim 4 wherein the crystallization solvent is selected from the group consisting of isopropyl alcohol, 1-propanol, butanol, a mixture of ethyl acetate and n-hexane and a mixture of n-hexane and MIBK.
9. A pesticidal composition comprising:
(a) a pesticidally effective amount of a compound according to claim 1 ; and
(b) a pesticidally acceptable adjuvant.
10. The pesticidal composition according to claim 9 in a form and amount effective for use in veterinary medicine, agriculture, treating fields or crops, household pest control, or roach, ant or termite control.
11. The pesticidal composition according to claim 9 , in a form suitable for percutaneous administration or topical administration.
12. The pesticidal composition according to claim 9 , in a form suitable for a spray, pest bait, granules, a gel or a solution.
13. A method for controlling pests at a locus, said method comprising applying to said locus a pesticidally effective amount of a composition according to claim 9 .