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

The possibility of using aluminum alkyls for the growth of acetylene oligomerization was studied utilizing an addition reaction different from the Aufbau reaction of ethylene. The investigations included exposing toluene solutions of AlEt 3 to acetylene at a pressure of 1 bar gauge, which resulted in double insertion in Al-hexadienyl groups. AlMe 3 exposed to acetylene under the conditions of 100°C and 1 brag acetylene show a dominant oligomer distribution made up of propane, 1,3-pentadiene, C 9, C 13, and C 17 products. It is also found that oligomerization of AlEt 3 follows removal of the volatiles under vacuum and formation of C 10+ fractions as a yellow liquid. The distribution of oligomers can be explained by a model whereby the rate of addition across the double bond is significantly greater than that for insertion.