Abstract: In the present invention, hydrated magnesium salts of the carboxylate group in certain aromatic or olefinically unsaturated peroxyacids such as monoperoxyphthalic acid or monoperoxymaleic acid are made by reacting the corresponding anhydride with aqueous hydrogen peroxide and a magnesium base, in the absence of a significant amount of free iron. By so doing, the process avoids the use of non-aqueous solvents such as ethyl acetate. Solid product can be obtained by using no more than enough hydrogen peroxide and water for solely a damp product to be obtained or by crystallization from an aqueous solution, preferably with recycle of the mother liquor. Preferably the reaction temperature is maintained at 5.degree. to 25.degree. C., employing 1.8 to 2.2 moles anhyhdride per mole of magnesium base, and 0.95 to 1.2 moles of hydrogen peroxide per mole of anhydride.The product can be used as a bleach and as a disinfectant.

Abstract: It has been suggested hitherto that the bleaching performance of hydrogen peroxide or persalts developing it in situ at ambient to hand hot (e.g. up to 60.degree. C.) temperatures can be enhanced by addition of a transition metal catalyst, but recent investigations revealed that when manganese is selected as catalyst its performance can range from nil enhancement to a substantial improvement.The present invention is based upon the recognition that manganese catalysis of hydrogen peroxide is promoted by the presence of at least an equimolar amount of calcium, barium or strontium compound, and preferably a molar ratio of at least 50:1.