Production Several organic peroxyacids are commercially useful. They can be prepared in several ways. Most commonly, peracids are generated by treating the corresponding
carboxylic acid with hydrogen peroxide: : A related reaction involves treatment of the carboxylic anhydride: : This method is popular for converting cyclic anhydrides to the corresponding monoperoxyacids, for example monoperoxyphthalic acid. The third method involves treatment of
acyl chlorides: :
meta-Chloroperoxybenzoic acid (
mCPBA) is prepared in this way: A related method starts with the peroxyanhydride. Aromatic
aldehydes can be
autoxidized to give peroxycarboxylic acids: : (Ar =
aryl group) The products, however, react with the initial aldehyde forming the carboxylic acid: :
Properties and uses In terms of acidity, peroxycarboxylic acids are about 1000 times weaker than the parent carboxylic acid, due to the absence of
resonance stabilization of the anion. For similar reasons, their p
Ka values tend also to be relatively insensitive to substituents; all are between 7.2 and 8.2. The most common use of organic peroxy acids is for the conversion of alkenes to epoxides, the
Prilezhaev reaction. Another common reaction is conversion of cyclic ketones to the ring-expanded esters using peracids in a
Baeyer-Villiger oxidation. They are also used for the oxidation of
amines and
thioethers to
amine oxides and
sulfoxides. The laboratory applications of the valued reagent
mCPBA illustrate these reactions. Reaction of peroxycarboxylic acids with acid chlorides affords diacyl peroxides: : The oxidizing tendency of peroxides is related to the
electronegativity of the substituents.
Electrophilic peroxides are stronger oxygen-atom transfer agents. The oxygen-atom donor tendency correlates with the
acidity of the bond. Thus, the order of oxidizing power is . ==Usage==