Abstract: The present invention relates to a method for the preparation of the 5-amino-1-phenyl-3-cyano-4-trifluoromethyl sulfinyl pyrazole having the described general formula (I), particularly preferred for the synthesis of Fipronil, through oxidation of a compound having the general formula (II) as follows: wherein R1 and R2 are independently hydrogen or halogen, and wherein the oxidizing agent is dichloroperacetic acid.

Abstract: The present invention relates to a method for the preparation of the 5-amino-1-phenyl-3-cyano-4-trifluoromethyl sulfinyl pyrazole having the described general formula (I), particularly preferred for the synthesis of Fipronil, through oxidation of a compound having the general formula (II) as follows: wherein R1 and R2 are independently hydrogen or halogen, and wherein the oxidising agent is dichloroperacetic acid.

Abstract: A method of purifying dinitroaniline of the general formula: ##STR1## in which: R is linear or branched C.sub.1 -C.sub.6 alkyl, C.sub.4 -C.sub.6 cycloalkyl, C.sub.1 -C.sub.4 monohaloalkyl or C.sub.1 -C.sub.4 alkoxy(C.sub.2 -C.sub.4)alkyl,Y is C.sub.1 -C.sub.4 alkyl, halogen or CF.sub.3, andX is hydrogen, halogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 monohaloalkyl, or C.sub.1 -C.sub.4 alkoxy(C.sub.1 -C.sub.4)alkyl, by N-denitration of the impurities of N-2,6-dinitroaniline contained therein, in the presence of a base selected from alkali-metal hydroxides, alkali-metal carbonates and ammonium hydroxide, at neutral or basic pH, comprising the treatment, with stirring, of the dinitroaniline to be purified, with an alcoholic organic solvent.

Abstract: A method for the purification of dinitroanilines having herbicidal activity by means of the known reactions of denitrosation using acid, and denitration in a neutral or basic environment in the presence of a phase-transfer catalyst, wherein:the denitrosation reaction is effected on the dinitration mixture containing the dinitroaniline of interest and the corresponding unwanted N-nitroso- and N-dinitroaniline impurities, and in the absence of solvent,the denitration reaction is conducted sequentially to the denitrosation reaction in the same reactor with the addition to the denitrosation product as such of an aqueous base, and of the said phase-transfer catalyst.

Abstract: A continuous process for the dinitration of alkyl-substituted derivatives of phenol and aniline, using nitric acid substantially free of sulphuric acid, characterized in which the dinitration is conducted in a single step in a tubular reactor in the presence of a catalytically-effective amount of a catalyst capable of reacting with the nitric acid to form nitrous acid in situ.

Abstract: A process for the preparation of the unsaturated dinitroaniline, ethalfluralin having a level of nitrosamines lower than 0.5 ppm and essentially free from the compound of addition of halogenhydric acid on the methallyl double bond, by treatment with aqueous halogenhydric acid, wherein crude ethalfluralin is treated under agitation with an aqueous solution of hydrobromic acid in the presence of sulfamic acid and a sulfur compound selected from the group consisting of bisulfites, metabisulfites, hydrosulfites, sulfurous acid and gaseous sulfur dioxide.

Abstract: Process for preparing N-phosphono-methyl-iminodiacetic acid by means of phosphonomethylation of iminodiacetic acid performed by reacting an aqueous solution of phosphoric acid and hydrochloric acid, obtained by hydrolysis of phosphorous trichloride, with iminodiacetic acid and formaldehyde, in which phosphorous trichloride is hydrolysed in step (a) with water or an aqueous solution or hydrochloric acid, the reaction temperature and amount of water are regulated such that an aqueous solution of hydrochloric acid and phosphoric acid in a molar ratio of 0.5:1 to 2:1 is formed, and gaseous hydrochloric acid is caused to develop from the reaction medium. The phosphonomethylation reaction is performed in the solution obtained in step (a) in the presence of iminodiacetic acid in a molar ratio of iminodiacetic acid to phosphoric acid between 1:1 and 1:1.2 with the addition of formaldehyde. The N-phosphono-methyl-iminodiacetic acid is then recovered from the reaction medium.

Abstract: N-phosphonomethyl glycine is prepared by the reaction of glycine with an aqueous-alcoholic solution of formaldehyde in the presence of a base selected from the group consisting of alkali and alkaline-earth metal hydroxides, the reaction of the solution thus obtained with a trialkylphosphite and hydrolysis in an aqueous medium, with recovery of the N-phosphonomethyl glycine by crystallization.

Abstract: The level of the nitrosamines which may be present in the unrefined trifluralin is reduced to a value below 0.5 ppm, by treating the unrefined trifluralin under agitation, at a temperature from 60.degree. to 90.degree. C., for a time between 10 minutes and 4 hours, with an aqueous solution containing from 15 to 50% by weight of hydrobromic acid in a ratio of 0.2 to 0.8 liters per kilogram of unrefined trifluralin, said aqueous solution of hydrobromic acid being added with an amount of sulfamic acid from 0.1 to 3 g per liter of solution and with an amount of bisulfite or an alkali metal corresponding to a content of sulphur dioxide from 0.3 to 1.2 g per liter of said hydrobromic acid aqueous solution.The so obtained refined trifluralin has a content of nitrosamines which is lower than 0.1 ppm.

Abstract: The present invention relates to a method for the preparation of the 5-amino-1-phenyl-3-cyano-4-trifluoromethyl sulfinyl pyrazole having the described general formula (I), particularly preferred for the synthesis of Fipronil I, through oxidation of a compound having the general formula (II) as follows: wherein R1 and R2 are independently hydrogen or halogen, and wherein the oxidizing agent is dichloroperacetic acid.