Published work on iridium pincer complexes for catalysis of alkane dehydrogenation demonstrates effective catalysis in transfer dehydrogenation reactions involving cyclic alkanes such as cyclooctane. With linear alkanes, additional progress is needed to achieve the selective formation of monoenes with high yields and high selectivity. We have modified a POCOP ligand precursor with a vinyl group at the <i>para</i>-position so that it can be copolymerized with styrene monomers into a polymer. The modified ligand was synthesized in four steps from 3,5-dihydroxybenzaldehyde. After the phosphination step, the vinylated ligand can be copolymerized with styrene via reversible addition-fragmentation chain transfer polymerization and the resultant polymer can be metalated with iridium. Using a previously reported small molecule catalyst as a benchmark, we are examining the catalytic activity of our polymer-bound iridium complexes and looking for changes in reactivity and selectivity. Namely, we are looking at transfer dehydrogenation of cyclooctane with tert-butyl ethylene as a hydrogen acceptor as a measure of reactivity and the transfer dehydrogenation of octane, again with tert-butyl ethylene as a hydrogen acceptor, as a measure of selectivity.

Iridium catalyzed alkane dehydrogenations: Can we improve reactivity and selectivity?

ACS Spring 2022

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