Radical reactions metal-free procedures

There are also useful synthetic procedures in which organotin compounds act as carbanion donors in transition metal-catalyzed reactions, as discussed in Section 8.2.33. Organotin compounds are also very important in free radical reactions, as is discussed in Chapter 10. 

Radiation chemistry can he used to study reactions of free radicals and of metal ions in unusual valency states, including electron-transfer reactions. In some instances, radiation chemistry facilitates experiments that can not he studied hy photochemistry, owing to differences in the fundamental physical processes in the two methods. Procedures have heen developed to accurately determine radiolysis radical yields, and a variety of physical techniques have heen used to monitor reactions. In particular, aqueous radiation chemistry has heen extensively developed, and many free radicals can he generated in a controlled manner in aqueous solution. There are extensive literature resources for rate constants and for experimental design for a variety of radicals. 

As with the silanes, some of the most useful procedures for synthetic applications of stannanes involve electrophilic attack on alkenyl and allylic derivatives. The stannanes are more reactive than the corresponding silanes because there is more anionic character on carbon in the C—Sn bond and it is a weaker bond. There are also a number of synthetic procedures in which organotin compounds act as carbanion donors in transition metal-catalyzed reactions. Organotin compounds are also used in free-radical reactions, as will be discussed in Chapter 10. 

DM-DCNQI was synthesized according to the published procedure (1). The anion radical salts of Cu and Na were prepared upon reduction of the acceptor by the corresponding metal Iodide, while silver powder was used as the reducing agent for the preparation of the Ag-salt (4). These reactions were carried out in CH3CN, and resulted in the powders of the anion radical salts. For spectral measurements, free-standing pellets were pressed from the prepared compounds. 

A free radical procedure for preparing Pb(CH3)4 and mixed tetraalkyllead compounds by passing CH3CI and other alkyl chlorides over a heated mixture of lead and an initiator metal, like copper, is described in [277]. Reaction of lead deposited as a mirror on the inside of a quartz tube with CH3 radicals formed by decomposition of di-tert-butylperoxide is employed to prepare Pb(CH3)4 from small amounts of lead, e.g., from minerals for mass spectrometric analysis [278, 279]. Pb(CH3)4 is formed by reaction of CH3 radicals with recoil products of 224Ra [280, 281, 282] see also [283]. 

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