Radicals, reduction thermal cleavage

These sites are passed to FEASIBLE-P, which searches the reaction-environment to establish potential radical forming processes thermal cleavage, photochemical cleavage, and oxidation-reduction processes. Attributes describing reaction-environment establish thermal cleavage as a likely initiation mechanism photochemical cleavage... 

In this section we present a short overview of the polymerization of VC. The most common method is polymerization by free radicals [305]. According to the ease of homolytic splitting of the n bond in the monomer, radical polymerization takes place in the presence of suitable initiation systems. In general, there are three methods for producing radicals available for the polymerization of VC (A) thermal cleavage of azo or peroxo compounds, (B) oxidation-reduction processes, and (C) metal alkyls in connection with oxygen. After the initiation step, chain growth takes place rapidly ... 

Not only persistent radicals can be reacted with low-valent metal complexes but also those that are generated in situ by the thermal cleavage of peroxides. To our best knowledge, so far, only samarium [41] and ytterbium [42] compounds were reported into which a tm-butoxide moiety was introduced by reduction of di-rcrr-butylperoxide by the metal center. Here, the first Cp-type titanium monoalkoxide complex synthesized by reacting a titanium(lll) species with di-tert-butylperoxide is reported. 

Thermal decomposition of L-AuRs compounds proceeds mainly with reductive elimination of R2 by radical cleavage, as outlined for L AuR. 

One-electron reduction of azobenzene yields the azobenzene radical anion. Its Z-form thermally isomerizes fast. This explains the cleavage/recom-bination mechanism reported for azosulfides and the reduction/oxidation mechanism of azobenzene derivatives in Langmuir-Blodgett monlayers... 

The reduction of (3-hydroxyalkyl selenides to alcohols has been achieved - - - by lithium in ethylamine (Scheme 161, a Scheme 162, a Scheme 163, a Scheme 167) or triphenyl- or tributyl-tin hydride in toluene, with or without AIBN. Most of these reactions proceed through radicals. The reactions involving tin hydrides can be carried out thermally around 120 or photochemically at much lower temperature (0-20 The cleavage of the C—SePh bond is faster than that of the... 

The significantly positive AV values clearly underline the dissociative nature of the reductive elimination process in both solvents. The reactive state is a thermally equilibrated MLCT excited state that can undergo nonradiative deactivation (kn) and simultaneous Pt—N3 bond cleavage (k,) to produce a caged radical species, which subsequently decomposes to Pt(CN)4 and N2 in both solvents, or interacts with ethanol to produce HN3 and ethanol radicals via the abstraction of hydrogen (fc3). The additional deactivation route in ethanol can account for the higher AV value. It follows that bond cleavage plays an important role in both deactivation routes k1 and k2. 

---