Base promoted etherification reaction of a non-polar reactive dye and methanol by zeolite KA

An unexpected base promoted etherification reaction of a non-polar 4,6-dichloro-1,3,5-triazine type reactive dye and methanol was observed when methanol was dried over zeolite KA. A dye conversion of 100% was measured after 3 min reaction time at room temperature, while, when methanol was not pre-contacted with zeolite KA the dye conversion was only 31% after 24 h. The rate constants of the two-step consecutive reaction between dye and methanol were calculated in order to determine the accelerating effect. At 293 K, k1 increased a factor of 3000 and k2 a factor of 26,000 compared to these values observed with undried methanol. It has been found that the ion-exchange properties of the zeolite KA are responsible for the base promoted reaction. Elemental analyses of the zeolite KA, pellets and powder, and methanol extracts showed an exchange of cations between the two phases. In the case of pellets the binder material contributes to the cation content of the methanol. The potential of zeolite KA as a base promoter is discussed.