Preparation of potential biofuel 5-ethoxymethylfurfural and other 5-alkoxymethylfurfurals in the presence of oil shale ash

5-Ethoxymethylfurfural (EMF) can be prepared from the corresponding halomethylfurfural and absolute ethanol in good yield. The use of significantly more affordable 96% ethanol results in formation of levulinic acid or its ester in considerable amount (up to 16%), which is difficult to separate from the desired EMF. In the present study we report that the addition of oil shale ash prevents the hydrolysis of the furan ring and enables the use of 96% ethanol with great success. The developed procedure is applicable to a wide range of aqueous alcohols, is operationally simple and utilizes an inexpensive basic ash, which is deposited in millions of tons per year. Notably, the basicity of the ash is decreased during the process, making its deposits less hazardous to the environment.