Mechanistic aspects of the cycloaddition of CO2 with propylene oxide using the trans-Ru(py)4Cl2 catalyst

Abstract

The mechanism of the cycloaddition of CO 2 with propylene oxide to afford propylene carbonate catalyzed by a highly active trans-dichlorotetrapyridineruthenium [trans-Ru(py) 4 Cl 2 ] complex and tetrabutylammonium chloride (TBAC) has been studied by means of electrospray ionization mass spectrometry (ESI-MS), structural characterization of trans-Ru(py) 4 Cl 2 , catalyst activity tests and so on. Further experiments demonstrated that the tributylamine formed in situ was involved in the catalysis and that addition of butyl chloride to re-convert the tributylamine into TBAC resulted in the inhibition of the reaction. The mechanistic study explains the reported early experimental observations well and provides a clear profile for the cycloaddition of carbon dioxide with propylene oxide using trans-Ru(py) 4 Cl 2 as catalyst. The mechanism also fully explains the role of the TBAC by providing a role for the in situ generated tributylamine in activating the carbon dioxide.

Influence of Temperature and Pressure on Cyclic Carbonate Synthesis Catalyzed by Bimetallic Aluminum Complexes and Application to Overall syn-Bis-hydroxylation of Alkenes

“…The mild reaction conditions under which complexes 1 and 2 were catalytically active facilitated a detailed kinetic study, which, combined with the detection of tributylamine formed in situ from the tetrabutylammonium bromide, allowed the catalytic cycle shown in Scheme to be proposed. , The use of quaternary phosphonium salts as cocatalysts in conjunction with complex 1 was shown to result in less active catalyst systems which is consistent with the important catalytic role played by the tertiary amine in Scheme . The main features of the catalytic cycle shown in Scheme have also been shown to be applicable to other catalyst systems for the synthesis of cyclic carbonates from epoxides and carbon dioxide. − …”

An Efficient Catalyst System at Mild Reaction Conditions Containing Rare Earth Metal Complexes

“…17 Prominent among these are transition metal complex catalysts. 18 In particular, metal complexes based on nickel, copper, zinc, cobalt and chromium are remarkable. 19 Various ligands have been developed, such as pyridine, quinoline, acridine, porphyrins, salen, phthalocyanines, et al 20 In many cases, salen complexes are moisture sensitive, and low-valent metal complexes are oxygen sensitive.…”