Effect of mercury chlorides on the activity of complex titanium-based catalysts for the cyclotrimerization of butadiene

Abstract

Mercury chlorides decompose arenetitanium(II) complexes by redox reactions, e.g. Ti2+ + Hg+ → Ti3+ + Hg0, and thus inhibit their catalytic activity in the cyclotrimerization of butadiene. The effect of mercury chlorides added to the TiCl4-Et3Al catalytic system depends on their ratio to organoaluminium compound. The cyclotrimerization activity is preserved when a sufficient excess of the latter is present, ensuring the reverse reduction of Ti(III) to Ti(II). A high cyclotrimerization activity and selectivity of the catalysts are achieved if Ti(II) is converted to trinuclear Al-Ti-Al complex under the effect of ethylaluminium dichloride.