Question

I'm working on a lab that's the Ziegler Natta Catalytic Formation of Polyethylene and at one point in the lab the lab manual says to:

"Turn off the ethylene and turn on the nitrogen. Add 95% ethanol (100ml) to the addition funnel and add this dropwise to the reaction mixture.

One of the questions is to "think of a reason why we flush with nitrogen before the addition of ethanol" and another is "why do we add ethanol? Why not water?", but I can't seem to think of any logical reasons besides that the reaction could be air sensitive. Can someone please help? I can provide more information of necessary.

Answer 1

When you are working on the Ziegler Natta Catalytic Formation of Polyethylene, you need to turn off the ethylene and turn on the nitrogen.

Explanation: The Ziegler-Natta catalyst (TiCl₄ + R₃Al) is the most sensitive to air and moisture as you are guessing. So, before you add the solvent, you need to flush with an inert atmosphere (nitrogen or argon) to remove any trace amount of air if present in the system.

And then you need to add ethanol dropwise through addition funnel in order to avoid any violent reaction of TiCl₄/R₃Al with the alcoholic solvent.

I hope you understood !!! All the very best !!!!!!