Synthesis of Low-Molecular-Weight Polyether Polyols by Self-Condensation of Diols over Amberlyst 15

Polyether polyols are widely utilized in a variety of fields ranging from the chemical, medicinal, and automotive industries. Applications vary depending on the molecular weight, and low molecular weight polyether polyols (200 to 1200 g mol –1 ) are primarily used as soft segments in polyurethanes. The atom-economical and environmentally friendly synthetic method is the acid-catalyzed self-condensation of diols. This type of reaction has the advantage that it produces only water as a byproduct and that it can use biomass-derived diols as a substrate; however, there is no report of heterogeneous catalysts to synthesize polyether polyols with low molecular weights in high yields through self-condensation of diols. We found that a strong acidic ion-exchange resin, Amberlyst 15, shows high catalytic performance for the self-condensation of α,ω-diols to give polyether polyols with low molecular weight in high yields. The present catalytic system could be applied to gram-scale reactions as well as neat conditions and reused three times without loss of activity. Moreover, in comparison with homogeneous acid catalysts such as sulfuric acid, Amberlyst 15 can suppress side reactions such as the dehydration of alcohols and achieve high yields while maintaining low molecular weight.