Selenium: dehydrogenation agent

The principal dehydrogenating agents are (i) sulphur, (ii) selenium, and (iii) catalytic metals. 

Other dehydrogenation agents include sulfur, selenium dioxide, palladium on charcoal, and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ). Some reactions proceed spontaneously. Dehydrogenation also occurred... 

Sulfur, Sj, is a dehydrogenating agent that converts compounds containing six-membered rings into their aromatic analogues. In the reaction, sulfur is reduced to hydrogen sulfide [491, 492], Such dehydrogenations occur at lower temperatures compared with those by selenium [493] or noble metals 495, 496, 497]. 

Otto Paul Hermann Diels (1876-1954) Diels obtained his Ph.D. in 1899 while studying with Emil Fischer at the University of Berlin. He later became Associate Professor of Chemistry at the University of Berlin, and in 1916 he moved to the University of Kiel. In 1906 Diels discovered carbon suboxide gas (C3O2), obtained from the dehydration of malonic acid. He did extensive studies on saturated fats and fatty acids. Diels also developed the use of selenium as a mild dehydrogenation agent. This latter work led to the commercial production of polyunsaturated oils. 

Benzeneseleninic acid and anhydride appear to be attractive alternatives to selenium dioxide as dehydrogenation agents of steroidal ketones (31) and amides (32). Potassium fencholate as the base, and fenchone as hydride acceptor, is an effective mixture for deprotonation-elimination of acidic C—H bonds, e.g. (33) to (34) in 90% yield." ... 

---