Azobis , catalysis

Peroxidic initiators, like dibenzoyl peroxide, are too reactive with phenolic and aminic moieties and can be applied only exceptionally [50], Inorganic peroxides, like potassium persulfate, were used for emulsion polymerization of functionalized monomers [51]. Phase transfer catalysis may be also applied using persulfate initiation. To circumvent problems with the peroxide initiation, 4,4 -azobis(4-cyanovaleric acid), a water soluble initiator, was successfully used [48]. 

A complete mechanism for the autoxidation of alkylaromatic hydrocarbons by cobalt(n) in acetic acid has not been established,25 6 although a complex rate law has been determined for tetralin. 22 The reaction most likely proceeds by a fiiee radical chain mechanism in which the purpose of the cobalt ions is to provide a hi h steady state concentration of free radicals by catalysis of the decomposition of THP. The free radical nature of the autoxidation of tettalin with the colloidal CoPy catalysts is supported by experiments which showed inhibition of the reaction by 2,6-di-rerr-butylphenol and 2,6-di-rm-butyl-4-methylphenol, and by a shortening of the induction period and increase of the reaction rate when azobis(isobut nitrile) was added to the reaction mixture as a free radical initiator. 

Pioneered works related to CD-based polymers for catalysis were reported by Nozakura s group. The model reaction was the hydrolysis of various p-nitrophe-nol esters [18]. The CD-based polymers synthesis was realized in a controlled two steps procedure. First, CD-acryloyl monomers were synthesized and purified by gel ehromatography through Sephadex G15. The monomers were then polymerized in an H20/Me0H mixture (v/v 1/1) using 2,2 -azobis (isobutyroni-trile) as an initiator to give polyacryloyl-CD polymers (Scheme 2.4). 

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