Abstract: Process for producing an aryl-imido-peralkanoic acid by means of the peroxidation with H.sub.2 O.sub.2 of the corresponding alkanoic (non-peroxy) acid, in the presence of a strong acid with a pKa value equal to, or lower than 3, and in the presence of a halogenated solvent, characterized in that said solvent is CH.sub.2 Cl.sub.2 or CHCl.sub.3, that the amount of alkanoic acid submitted to peroxidation is equal to or smaller than the solubility threshold of said alkanoic acid (in said solvent) and that a solution of said acid in said solvent is reacted with H.sub.2 O.sub.2 (at 10.degree.-35.degree. C.), with the molar ratio of said strong acid to said alkanoic acid being lower than 2.

Abstract: There are described mixes, which are curable by using radical intermediates, are based on fluoroelastomers containing bromine or iodine, exhibit, during curing, a low emission of toxic vapors of methyl bromide or iodide and are characterized in that they contain, as cross-linking agents, peroxides having the following formulas: ##STR1## wherein the substitutents from R.sub.1 to R.sub.17 have the significances defined in the specification.