Cannizzaro reaction electron transfer mechanism

Fuentes, A., Sinisterra, J. V. Single electron transfer mechanism of the Cannizzaro reaction in heterogeneous phase, under ultrasonic conditions. Tetrahedron Lett. 1986, 27, 2967-2970. 

Possible mechanisms for formation of the functionalized polymer products are shown in Scheme 4. Because of both electron transfer mechanisms, Cannizzaro reactions and oligomerization, the functionalization of PSLi with formaldehyde produces a complex mixture of products and is not a useful reaction. 

Self-Condensation. Use of Electron-Release Caialyst (Cannizzaro reaction). Fundamentally, the base-catalyzed Cannizzaro reaction involves the reaction between two molecules of an aldehyde containing no a-hydrogen atoms. The overall result is the transfer of one aldehyde hydrogen to another aldehyde group, thus producing two radicals that could combine to form an ester. The presence of the basic catalyst prevents the ester formation, and an alcohol and a metal carboxylate result. The mechanism can be shown as follows ... 

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