Rhodium Catalyzed Carbonylation of Ethylene and Methanol in the Absence of Alkyl Halides Using Ionic Liquids

摘要

Rhodium catalyzed carbonylations of olefins and methanol can be operated in the absence of an alkyl iodide or hydrogen iodide if the carbonylation is operated in the presence of iodide-based ionic liquids. In this chapter, we will describe the historical development of these non-alkyl halide containing processes beginning with the carbonylation of ethylene to propionic acid in which the omission of alkyl halide led to an improvement in the selectivity. We will further describe extension of the non-alkyl halide based carbonylation to the carbonylation of Me0H (producing acetic acid) in both a batch and continuous mode of operation. In the continuous mode, the best ionic liquids for carbonylation of Me0H were based on pyridinium and polyalkylated pyridinium iodide derivatives. Removing the highly toxic alkyl halide represents safer, potentially lower cost, process with less complex product purification.