Etherification of glycerol with tert-butyl alcohol catalysed by ion-exchange resins

The reaction of glycerol with tert-butyl alcohol in the liquid phase on acid Amberlyst-type ion-exchange resins was studied. The influence of temperature, mole ratio n(TBA)/n(G), water and swelling of gel, and macroreticular type of polymer catalysts on etherification reaction was investigated. The most favourable reaction temperature is 75°C. The conversion of glycerol and yield of glycerol tert-butyl ethers has increased with the mole ratio n(TBA)/n(G). Dry form of macroreticular catalysts provided the best results. Etherification reaction of glycerol with isobutylene in non-aqueous conditions gives the highest yield of desired ethers. The influence of water was studied. The gel forms of ion-exchange resins have very low catalytic activity. It can be concluded that water has an inhibition effect on ion-exchange resins. By comparing the gel and macroreticular forms of Amberlyst ion-exchange resins it can be concluded that very acid forms of macroreticular ion-exchange resins with a high degree of crosslinking are more active catalysts for the studied reaction due to their pores which are sufficiently large so that the voluminous tert-butyl ethers of glycerol can be formed. It was estimated that tert-butyl alcohol as tert-butylation agent is not suitable for etherification of glycerol with the formation of di-and triethers.