Sleeping Beauty effect

Interestingly, the presence of hydrogen sulfide, which is much more easily oxidized than the saturated hydrocarbon, did not inhibit the reaction but, in contrast, was an essential additive. Later, it was shown that the same holds true for other easy-to-oxidize compounds such as Ph2S, PPh3 and P(OMe)3. It was assumed that the iron species that attacks the alkane is only activated by contact with it (called the Sleeping Beauty Effect by Barton). This observation is known as the Gif paradox [2]. 

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