TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The solvent system in the step (I) comprises at least one solvent selected from trichloroacetic acid, monobromoacetic acid, dibromoacetic acid, tribromoacetic acid, chlorobenzene, dichloromethane and dichloroethane (preferably monobromoacetic acid, dibromoacetic acid, and/or tribromoacetic acid). Preferred Process: The process further involves purifying the trifluoromethylsulfinyl pyrazole compound (I) by crystallization and/or leaching (preferably crystallization using at least one solvent selected from chlorobenzene and ethylacetate; especially chlorobenzene (2-10, preferably 3-4) parts per part of the compound (I)), followed by leaching the compound (I) in a solvent mixture (preferably a solvent mixture consisting of chlorobenzene (5-100 vol./vol.%) and ethyl acetate, to give pure compound (I) having a purity of greater than 98%. ACTIVITY - Pesticide. No biological data given.    MECHANISM OF ACTION - None given.    EXAMPLE - N-Methylpyrrolidone (NMP) (1050 ml) was charged in an autoclave along with anhydrous activated potassium fluoride (102 g), and 3,4-dichlorobenzotrifluoride (377 g) was added. Ammonia (158 g) gas was passed in reactor from pressure pot at ambient temperature. The content of reactor was heated to 245-250 degrees C over 2 hours to get reactor pressure of 30-32 kg/cm2. Excess NH3 was fed from the pressure pot to maintain the reactor pressure at 38-40 kg/cm2 at 245-250 degrees C liquid temperature. Mixture was maintained at 245-250 degrees C and at 38-40 kg/cm2 pressure for further 8 hours, and then worked up to give 2-chloro-4-trifluoromethylaniline and 2-chloro-5-trifluoro methyl aniline. Mixture (301 g) of 2-chloro-4-trifluoromethylaniline, 2-chloro-5-trifluoromethylaniline and NMP (1.06 m/m) was mixed with chlorobenzene (500 ml). Sulfuryl chloride (148.4 g) was added to the mixture at 55-60 degrees C over 4 hours and reaction mixture was maintained at 55-60 degrees C for 4 hours. Reaction medium on treatment and fractionation gave 2,6-dichloro-4-trifluoromethylaniline. To 2,6-dichloro-4-trifluoromethylaniline (230 g) and acetic acid (150 ml) was added nitrosyl sulfuric acid (1.1 m) over 1 hour at 30 degrees C and maintained for 1 more hour. The mass was heated to 50-55 degrees C over 0.5 hour, and absence of 2,6-dichloro-4-trifluoromethyl aniline was monitored. The mass was then cooled to 30 degrees C and excess nitrosyl sulfuric acid was destroyed. The obtained diazotized mass was added to a mixture of acetic acid (250 ml), ethyl-2,3-dicyanoproprionate (162 g) and water (425 ml) over 4-5 hours maintaining temperature at 0-5 degrees C, and further maintained at 0 degrees C/2 hours, 5 degrees C/1 hour, 10 degrees C/1 hour, 15 degrees C/1 hour, and solution was extracted with methylene dichloride (3x 250 ml). Layers were separated. Dichloromethane (DCM) layer was washed with water (250 ml), cooled to 0 degrees C and washed with 8N aqueous NH3 (250 ml) under stirring for 1 hour. Layers were separated, DCM layer was taken and NH3 gas was passed at 0-5 degrees C till free NH3 was observed on top of the condenser and maintained the reaction mass for 3-4 hours at 0-5 degrees C, and then the reaction was worked up to give 5-amino-3-cyano-1-(2,6-dichloro-4-triflouromethyl pheny1)-pyrazole. Trichloromethylsulfinyl chloride (193 g) was added to a mixture of water (500 g) and methylene dichloride (100 ml), along with sulfur dioxide (83 g) at 10 degrees C, over 4 hours. Reaction was terminated, when trichloromethylsulfinyl chloride was less than 1%. Layer separation gave thiophosgene which was added to a stirred mixture of activated KF (175 g), ortho-chlorobenzyl chloride (110 g) and Spherogel (RTM: chromatography column) (340 g, with 2 mm diameter), at 60 degrees C, over 3 hours and further maintained at 60 degrees C for 2 hours to give 98% conversion. Ortho-chlorobenzyl trifluoromethylsulfide (138 g) was isolated by filtration, followed by distillation, added to methylene chloride (500 ml), cooled to 0-10 degrees C and chlorine gas (41 g) was bubbled into it, the reaction was maintained for 2 hours and then heated slowly to 40-45 degrees C. Generated trifluoromethylsulfenyl chloride was passed in to a solution of 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethyl pheny1)-pyrazole in methylene dichloride to obtain 5-amino-1-(2,6-dichloro-4-trifluoromethylpheny1)-3-cyano-4-trifluoromethylthiopyrazole. A mixture (700 g) of dichloroacetic acid and trichloroacetic acid was taken along with chlorobenzene (300 g), boric acid (2 g) and 5-amino-1-(2,6-dichloro-4-trifluoromethylpheny1)-3-cyano-4-trifluoromethylthiopyrazole (280 g), and content were cooled to 15-20 degrees C. Aqueous H2O2 (44.2 g, 50%) was added and mass was stirred for 20 hours. The mass was then processed and Fipronil (5-amino-(2,6-dichloro-4-(trifluoromethyl)phenyl)-4-((1(R,S)-trifluoromethyl)sulfinyl)-1H-pyrazole-3-carbonitrile) was isolated by filtration. After work up, Fipronil (269 g, having purity of 94%) was obtained. The filtered Fipronil was then purified using chlorobenzene (5 ml/g) followed by mixture (1 ml/g, 80:20 vol./vol.) of ethylacetate and chlorobenzene to obtain Fipronil (232 g, having purity of greater than 97%). Further, for purification of Fipronil, the Fipronil was treated with mixture (232 ml) of ethylacetate and chlorobenzene (80:20 vol./vol.). This reaction mixture was heated to 85-90 degrees C and maintained for l hour. It was further cooled up to 30 degrees C in stages and filtered. The Fipronil thus obtained had a purity of 98%.