Nitronyl function

By competitive experiments spin trapping rate constants of other nitrones were obtained for t-butoxy and benzoyloxy radicals (5, J6). The values found are given in Table 1. Two features of the rate data are noteworthy (1) Phenyl or methyl substitution on the carbon atom of the nitronyl function slows the reaction ... 

Thus in the addition to PBN of benzoyloxy or t-butoxy radicals, both electronegative radicals, one gets the picture that the nitronyl function is rather electrophilic itself or the site of radical attack is quite elctrophilic, for if it were otherwise... 

Of interest are the simulations of the addition of an oxy radical to the nitronyl function. Here instead of using the parameters for a carbon atom for C2 an atom with otQ a +1.03 was used. At 3i 2 approaching radical has no spin but instead a full negative charge. Thus HMO predicts charge transfer when an oxy radical approaches a nitrone function ... 

A comparison of the magnitudes of the absolute rate constants of addition is also of interest. It would seem at first sight that the rapid rate of radical addition to the nitronyl function is unusual since unsaturated functions containing heteroatoms are not known to accept radicals readily. Radicals preferentially... 

Several anion-biradicals have been recently reported, which are composed of semiquinone and nitroxide functionalities. Such anion-biradicals are obtained by electron transfer to the p-benzoquinone (BQ) substituted by a nitronyl (Shultz and Farmer 1998) or nitronyl-nitroxide (NN) group (Kumai et al. 1994). Scheme 1.33 gives the BQNN example. 

Figure 26 Scheme for the functionalized ferrocene moieties with organic radicals as dimers or trimers (a) perchlorotriphenylmethyl, (b) and (o) nitronyl nitroxide. 

A new approach to functionally substituted nitroxides has recently been developed based on using the Sn reaction [37] of azine M-oxides with the lithium salt of nitronyl nitroxide (Scheme 15) [38]. 

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