Revisiting the Aufbau Reaction with Acetylene: Growth at Aluminium Producing a Unique Oligomer Distribution

Revisiting the Aufbau Reaction with Acetylene: Further Insights from Experiment and Theory

“…We have recently been exploring the metal-catalyzed oligomerization of acetylene to liquid products. , Acetylene/hydrogen mixtures can be produced by natural gas pyrolysis; hence this step coupled with acetylene oligomerization to fuel-range products represents a potential alternative gas-to-liquid (GTL) methodology. − While trialing a range of potential catalysts based upon transition metal and lanthanide complexes, we were surprised to discover that the majority of chain growth was in fact occurring at the cocatalyst, triethylaluminum …”

“…While we have investigated the reaction between AlEt 3 and acetylene in some depth, , a number of observations remain to be accounted for. The first insertion of acetylene into the Al−Et bond is reasonably facile, yet the subsequent insertion is more difficult.…”

Acetylene Cyclotrimerization with an Iron(II) Bis(imino)pyridine Catalyst

“…While a route involving selective acetylene hydrogenation to ethylene, followed by oligomerization, has been developed by Hall and co-workers, , we and others were interested in direct conversion of acetylene to fuel-range products. Initial studies from our group showed that a variety of early-transition-metal metallocene catalysts displayed very low activity, and in fact acetylene oligomerization occurs mainly at the cocatalyst, triethylaluminum (“Aufbau” with acetylene). , More recently, a survey of several middle- to late-transition-metal imine complexes revealed that the iron(II) bis(imino)pyridine complex 1 , previously developed for ethylene polymerization, − is an extremely active catalyst for acetylene polymerization after activation with methylaluminoxane (MAO). , This system produces polyacetylene gels and films with unprecedented activity, although rapid deactivation occurs due to encapsulation by the insoluble polymer. Extension of this catalyst class to oligomer production was therefore of interest, and without polymer formation the catalyst was expected to have a significantly greater lifetime.…”

“…Initial studies from our group showed that a variety of early-transition-metal metallocene catalysts displayed very low activity, 4 and in fact acetylene oligomerization occurs mainly at the cocatalyst, triethylaluminum ("Aufbau" with acetylene). 5,6 More recently, a survey of several middle-to latetransition-metal imine complexes revealed that the iron(II) bis(imino)pyridine complex 1, previously developed for ethylene polymerization, 7−9 is an extremely active catalyst for acetylene polymerization after activation with methylaluminoxane (MAO). 10,11 This system produces polyacetylene gels and films with unprecedented activity, although rapid deactivation occurs due to encapsulation by the insoluble polymer.…”

High activity acetylene polymerisation with a bis(imino)pyridine iron(ii) catalyst

“…We have been exploring the metal-catalysed oligomerisation of acetylene as a potential route from methane via acetylene to liquid synfuels. [15][16][17] As part of this study, we have investigated the well known bis(imino)pyridine iron ethylene polymerisation catalysts, [18][19][20] which have hitherto not been employed in acetylene conversion. 21 Herein we report the surprising finding that precatalyst 1, in combination with methylaluminoxane (MAO), leads to a highly active catalyst for acetylene polymerisation.…”