Alkoxy radicals phenoxy

Numerous different mechanistic approaches have been applied for this combination. First, cyclization of phenoxy-ethanols 203, in the presence of (diacetoxyiodo)benzene and iodine, gave a mixture of 1,4-benzodioxane 13 and 6-iodo-l,4-benzodioxane 204 via alkoxy radicals (Equation 36) <1997J(P 1)787, 1996TL2441>. 

Phosphites with substituted phenoxy groups also behave as peroxy and alkoxy radical scavengers forming relatively stable phenoxy radicals, which again eliminate peroxy radicals. Reaction (4.55) ... 

The mechanism by which BHT, a simple phenolic, functions is shown in Figure 14.3. A hindered phenol, when used alone, will react with two radicals. It then becomes spent and it wiU no longer protect the polymer. These reactions are only simplihed overviews. More complex and undesirable side reactions can occur. For example, quinone formation by the reaction of an alkoxy radical at the para position of the phenoxy radical leads to color development because of the conjugated diene structure [18]. 

Also, it was found that hexaarylbisimidazole will initiate polymerizations as a result of irradiation with visible light. The same is true of bisacylphosphine oxde. Other eompounds are ketocoumarins that are efficient photoinitiators for acrylic and methacrylic monomers in the presences of amines, phenoxy acetic acid, and alkoxy pyridinium salts. It was also shown that free-radical initiation is possible through visible light decomposition of ferrocenium salts in a three component composition, combined with either a hydroperoxide or a epoxide, and a third ingredient, a dicyanobutadiene derivative ... 

---