Assessment of the Ratio of Geometric Isomers of Dibenzalacetone Spectroscopically

Abstract

The aim of this experiment is to estimate the relative ratio of geometric isomers of Dibenzalacetone that was prepared via the crossed-aldol condensation by reacting benzaldehyde with acetone. Dibenzalacetone was synthesized in the lab from benzaldehyde and acetone under basic conditions. The GC-MS was used to relate the molar mass of the product. Thin layer chromatography was used to visualize the relative RF factor for each isomer. Uv-Vis instrument showed three peaks that were assigned to each isomer. And the FT-IR was used for the assignment of the vibrational modes of each isomer. The relative ratio of trans-trans, Cis-trans, and Cis-Cis was 59.87%, 26.53%, and 13.60% respectively with the aid of FT-IR instruments peak assignments were made for the vibrational frequency of the functional groups. For organic laboratory setups and practices, the fragments from the MS spectrum of DBA can be explained based on cleaving or rearrangement in gas phase by mechanisms known as α-cleavage, β-cleavage, and Rearrangement migration.