Hydroformylation, a reaction that adds carbon monoxide and dihydrogen across an unsaturated carbon-carbon multiple bond, has been widely employed in the chemical industry since its discovery in 1938. In contrast, the reverse reaction, retro-hydroformylation, has seldom been studied. The retro-hydroformylation reaction of an aldehyde into an alkene and synthesis gas (a mixture of carbon monoxide and dihydrogen) in the presence of a cyclopentadienyl iridium catalyst is now reported. Aliphatic aldehydes were converted into the corresponding alkenes in up to 91% yield with concomitant release of carbon monoxide and dihydrogen. Mechanistic control experiments indicated that the reaction proceeds by retro-hydroformylation and not by a sequential decarbonylation-dehydrogenation or dehydrogenation-decarbonylation process.
Hydroformylation, a reaction that adds carbon monoxide and dihydrogen across an unsaturated carbon–carbon multiple bond, has been widely employed in the chemical industry since its discovery in 1938. In contrast, the reverse reaction, retro‐hydroformylation, has seldom been studied. The retro‐hydroformylation reaction of an aldehyde into an alkene and synthesis gas (a mixture of carbon monoxide and dihydrogen) in the presence of a cyclopentadienyl iridium catalyst is now reported. Aliphatic aldehydes were converted into the corresponding alkenes in up to 91 % yield with concomitant release of carbon monoxide and dihydrogen. Mechanistic control experiments indicated that the reaction proceeds by retro‐hydroformylation and not by a sequential decarbonylation–dehydrogenation or dehydrogenation–decarbonylation process.
Following publication of this Communication, Dr.Boy Cornils (Hofheim, Germany) kindly informed the authors about the missing references for the retro-hydroformylation reaction. In the late 1960s, Orlicek [1] and inventors from Ruhrchemie AG [2] reported that cracking of isobutyraldehyde into propylene, carbon monoxide, and hydrogen was possible. The work was also published in academic literature in 1972. [3] In this reference, the two authors reported about the cracking of isobutyraldehyde, an undesired sideproduct of the oxo-process, to recover propylene and syngas using rhodium on alumina as acatalyst. Dr.C ornils comments that in 1972, his group confirmed the data in am onths-andmonths run on apilot plant scale. He says "it worked but not economically enough for industrial scale application." In addition, in 1968, Tsuji et al. reported the formation of nonene as amajor product in their attempt for decarbonylation of decanal with aheterogeneous palladium catalyst. [4]
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