In Situ DLS/EPR/GC-MS Monitoring of the Catalytic Systems Based on Tungsten(VI) Hexachloride and Organo-Aluminum Compounds for Olefin Metathesis Reactions

Abstract

Dynamic light scattering (DLS), electron paramagnetic resonance (EPR), and gas chromatography-mass spectrometry (GC-MS) methods were used to study interaction products of catalytic system components consisting of organoaluminum compounds (OAC), WCl6, and ethyl alcohol. Organic radicals (g = 2,0037, ∆H = 1,7mT) and W⁵⁺ complexes (g_z = 1,746, g_y = 1,820, g_x = 1,842, g₁ = 1,9957, g₂ = 1,9540, g₃ = 1,9465 at 77 K, and g₀ = 1.9583 at 300 K) with an additional hyperfine structure from two chlorine nuclei ^35,37 Cl have been identified by the EPR method. The formation of such compounds is accompanied by ethane and ethylene release. It is shown that a Cl₆/Et₃Al (Et₂AlCl)/EtOH-based catalytic system of olefin metathesis is a colloidal solution at the initial stages of the interaction of components. The further action of OAC leads to the formation of a molecular solution.