Perfluorinated peroxides

A very different route to soluble PPP derivatives was demonstrated by Yoshino and coworkers [586], who introduced perfluorinated alkyl substituents into PPP 471 by reaction with perfluorobutanoyl peroxide. The resulting modified polymer 475 was soluble in common organic solvents and a solution-fabricated PLED ITO/475/Mg In emitted blue to green light (depending on voltage) with band half-width of over 200 nm. 

Selenium-catalysed epoxidations have been carried out using a perfluo-roalkylated phenylselenide together with hydrogen peroxide, as shown in Scheme 9.6 [13]. The catalyst could be recycled 10 times with no loss of activity, with the toxic selenide immobilized in the perfluorinated solvent. 

Alkaline hydrogen peroxide oxidation52 has been extended to higher perfluorinated alk-1-enes, perfluorinated cycloalkenes and certain alkenes with internal C = C bonds.52 57 A convenient reagent for the preparation of perfluoroalkene epoxides is sodium hypochlorite in a mixture with aqueous acetonitrile or another aprotic solvent. Several cis- and traw.s-perfluoroalkenes are oxidized to 32 with retention of configuration (Table 4).58-63... 

The a-hydroxy peroxides 2 obtained by the above reaction can be used as oxidizing agents for perfluorinated or highly fluorinated aldehydes to transform them also to a-hydroxy peroxides.186... 

The terminal nitroso group in perfluorinated m-nitroso aliphatic carboxylic acids is readily oxidized by hydrogen peroxide and also by dinitrogen tetroxide to give nitro acids 11.250... 

Neumann R, Neimann K (2000) Electrophilic activation of hydrogen peroxide selective oxidation reactions in perfluorinated alcohol solvents. Org Lett 2 2861-2863... 

With < 1 mol% MTO cyclobutanones are fully converted within one hour. Another approach consists of the use of a fluorous Sn-catalyst under biphasic conditions [245]. A perfluorinated tin(IV) compound, Sn[NS02C8F17]4, was recently shown to be a highly effective catalyst for BV oxidations of cyclic ketones with 35% hydrogen peroxide in a fluorous biphasic system (Fig. 4.83). The catalyst, which resides in the fluorous phase, could be easily recycled without loss of activity. 

Photochemical reactions of HFA with perfluorinated carbon-oxygen compounds have been reported (271, 272). HFA serves as a mild source of CO in the reaction with bis(trifluoromethyl) peroxide (271) to yield bis(trifluoromethyl) carbonate with perfluoromethyl oxalate, CF3 radicals are the reactive species to yield perfluoromethyl acetate (272). 

Also, intermediate peroxides are formed in the oxidation of perfluorinated alkenes, e.g. in the photo-oxidation of perfluoroethene and perfluoropropene for the formation of Fomblin (Ausimont Co.) perfluoro-polyether fluids [198, 199]. 

Table 5. Selenium-catalyzed epoxidation of alkenes with hydrogen peroxide in perfluorinated solvents...

The apparent activation energy for the y-ray induced formation of carbonyl difluoride is calculated to be 18.0 kj moP . The kinetics results indicate a chain mechanism in which primary radicals formed from the irradiation of CjF, induce its copolymerization with Oj-The resulting long-chain peroxide radicals decompose by splitting off COFj or CjF O, depending upon whether a carbon-carbon, or oxygen-oxygen bond is broken. The perfluorinated cyclopropane is considered to be formed independently, in a minor side-reaction [420]. 

B. Betzemeier, F. Lhermite, P. Knochel, A selenium catalyzed epoxidation in perfluorinated solvents with hydrogen peroxide, Synlett (1999) 489. 

A major advantage of MTO is that it does not decompose hydrogen peroxide. This is in striking contrast to many other oxidation catalysts. Turnover numbers of up to 2500 mol product/mol catalyst (reaction conditions 0.1 mol% MTO, 5 mol% pyrazole) and TOFs of up to 14000 mol product/mol catalyst per hour have been reported, with typical MTO concentrations of 0.1-1.0mol%. However, these impressive results have only been reached in perfluorinated alcohols as solvents with cyclohexene as substrate [52]. 

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