Tetraphenylethylene, from benzophenone

Thermal generation of dimethylsilylene in the presence of carbonyl compounds leads to the addition of the silylene to the C=0 bond with the formation of oxasilirane (e.g. 62 and 65), followed by rearrangement40. Formation of tetraphenylethylene from benzophenone was attributed to carbenic fragmentation of the oxasilirane (62), whereas aliphatic ketones... 

A similar condensation of thioacetophenone fails with copper powder but is accomplished over Raney nickel. Copper bronze, however, is successfully used in the preparation of tetraphenylethylene from thio-benzophenone. ... 

In addition to the rather trivial differences mentioned above, laser irradiation can also lead to products as a result of reexcitaion of the carbenes. Thus, excitation of 30 in isooctane with a pulse of the 249-nm line from a KrF excimer laser results in the formation of 9,10-diphenylanthrancene (103), 9,10-diphenylphenanthrene (104), and fluorene, in addition to tetraphenylethylene (Scheme 9.31). Conventional lamp irradiation of 30 results in the formation of benzophenone azine as a major product. None of the products mentioned above are detected. Moreover, the yield of both 103 and fluorene increased markedly with increased laser power. While the details of the mechanism of this reaction are not certain yet, it is clear from the dependence on laser power that some of these products arise from carbene photochemistry. " ... 

Diphenyldiazomethane is reversibly oxidized at a platinum electrode to a dia-zonium radical cation 93 (Eq. (181) ) that reacts with excess diphenyldiazomethane 94 in a radical chain process to form tetraphenylethylene (95) as the main product and benzophenone (96) and benzpinacolin (97) as side products resulting from chain termination 387). 

This procedure is adapted from the method of Schlenk and Bergmann.3 Tetraphenylethylene has been prepared by the reaction of diphenylmethane with diphenyldichloromethane 4 by the reaction of diphenyldichloromethane with silver or zinc 4 by the reaction of thiobenzophenone with copper 6 by the reaction of diphenylmethane with sulfur 6 by the reduction of benzophenone with amalgamated zinc in the presence of hydrochloric acid 7 and by the rearrangement of 1,2,2,2-tetraphenylethanol with acetyl chloride.8... 

One of our earlier attempts to form a cross diperoxide used a variation of olefin types 4 and 5. In this case equimolar amounts of tetra-phenylethylene, 6, and tetramethylethylene, 7, were ozonized together. While ultimately both acetone diperoxide and benzophenone diperoxide could be isolated from the reaction mixture, it became apparent that these olefins have such different reactivities toward ozone that the tetramethylethylene was selectively ozonized. Only after most of the tetramethylethylene had been ozonized was the tetraphenylethylene attacked. The opportunity for cross diperoxide formation in this case is thus minimal. 

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