Comparison of selectivity of ethylene glycol synthesis and glyceraldehyde biomolecule through Formose reaction in water and methanol solvent

In the present paper, the Formose reaction to produce polyols in methanol solvent in the presence of an aerosil (fumed silica) catalyst is first investigated. The mechanism of Formose reaction is actually the same aldol condensation that occurs in an alkaline media and is accelerated by the presence of a heterogeneous catalyst. The products observed in the reaction medium are ethylene glycol and glyceraldehyde. Finally, the selectivity of the synthesis of these products was compared and evaluated with the two corresponding products synthesized through the Formose reaction in aqueous solvent. The present study shows that in the presence of fumed silica catalyst in aqueous solvent, the production of ethylene glycol decreases with increasing pH from 7.6 to 9.3, while the conversion of ethylene glycol to glyceraldehyde increases. As a result, the amount of ethylene glycol in the reaction mixture decreases at alkaline pHs compared to neutral pHs; in contrast, the selectivity of the reaction to the production of glyceraldehyde increases. Changing the solvent from water to methanol also reduces production efficiency. Therefore, it indicates the low selectivity of the methanolic medium compared to the aqueous medium to produce two products, 1,2-ethanediol and 2,3-dihydroxypropanal.