Syngas reactions: Part VIII : The preparation of glycol monoalkyl ethers

Abstract

The generation of ethylene glycol monoalkyl ethers (HOCH 2CH 2OR, R = Me, Bu) from synthesis gas, formaldehyde and the corresponding alkanol is described using homogeneous cobalt carbonyl catalysts coupled with three classes of catalyst modifiers — Group VIB donor ligands such as Ph 2Se and Ph 2S, η-pentahapto ligands such as η 5-C 5H 5 and η 5-C 5Me 5, and a series of aryl- and alkyl-substituted germanium and tin promoters such as Ph 3GeBr, Ph 3GeH and Bu 3SnCl. Both isomeric forms of the corresponding propylene glycol monoalkyl ethers may be prepared from synthesis gas, acetaldehyde (or its acetal) and the corresponding alkanol, using either cobalt-germanium, or homogeneous cobalt-rhodium or cobalt-ruthenium catalyst combinations. The mechanism of ethylene glycol monobutyl ether formation has been probed through preliminary rate measurements, coupled with 13C-enrichment and I R spectral studies. Catalyst multicycling has been demonstrated.