Flip (Hive Bee)
08-02-02 17:48
No 340222
      some general info on organic peracid stability  Bookmark   

Instytut Chemii i Technologii Organicznej, Politechnika Śląska, ul. Krzywoustego 4, 44-100 Gliwice


Organic peroxides are an interesting group of organic compounds. The O-O bonds in their structure warrant their properties determining the range of their application. The chemistry of peroxy substances is a branch of knowledge which is continuously developing. In the course of recent years much progress has been achieved both in the field of synthesizing new peroxides systems and in applaying them, particularly concerning their biological transformations.

A peroxide bond displays a low dissociation energy (20-50 kcal/mol) and that is why they are rather unstable. The reactions of peroxy substances may be divided into homolytic (radical) and heterolytic (ionic) ones. The most popular reaction of the monomolecular homolytic decomposition of the peroxide bond into radicals, occuring under the influence of temperature or radiation, is typical for all classes of peroxy substances and has found practical application. Theretically possible is also a molecular heterolytic decomposition of the peroxide bond into ions. Such a decomposition cannot compete, however, with the homolitic one and is required only in few specific cases. The O-O bond can also undergo transfomations in result of reactions with other substances. Also these reactions may be divided into two fundamental types. Some peroxy substances, e.g. hydroperoxides and peroxy acids, are electron donors and may occur in the reactions as nucleophiles. On the other hand, peroxy substances display the properties of "soft electrophiles" reacting with nucleophilic reagents. The result of such a reaction is a heterolytic decomposition of the peroxide bond. This ambivalent feature of peroxy substances becomes most visible in the natural process of peroxy acids in a basic medium, in which the RCO3- ion plays the role of a nucleophile attacking the non ionized particle (the electrophile).

In recent years it has been more and more often stipulated that the reactions of peroxides with nucleophiles run in compliance with the mechanism of the electron transfer (SET) from the nucleophile particle to the oxygen atom of the peroxy bond, in the result of which radicals and radical ions are formed in the course of this reaction. It ought to be stressed that it is extremely difficult to determine the mechanisms of many reactions of peroxy substances explicitly, because these types of reactions (SN2, SET) may take place simultaneously and in most cases lead to the formation of some products.

                   Wiadomości Chemiczne, 2000, 54, 1023.

Just making note of this information, which may be of general use to someone at some point in time; the dissociation energy of peroxide bonds, and a bit of detail as to how they function.  Found this rather interesting so I figured i'd throw this out.