Experiment 5 Synthesis And Spectroscopy Of Ethyl Cinnamate Essay
Wittig reactions involve the stereoselective synthesis of olefins from phosphonium ylides and aldehydes or ketones, where the carbonyl bond is converted to an alkene double bond.1 The variety of suitable reagents and the relatively mild experimental conditions facilitate their industrial applications, such as the synthesis of epoxides, esters, carotenoids and vitamin A.2,3 Specifically, the ester ethyl cinnamate is used as a flavouring agent and in perfumes.
The diastereomers of the alkene are distinguished through Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy, where the coupling constants of alkenyl protons are different for (E) and (Z) isomers.4 It is often that only one diastereomer of alkenes is biologically active3, and therefore it is important to understand the high yield production of the desired isomer through Wittig reactions.
In this experiment, (ethoxycarbonylmethyl)triphenylphosphonium bromide and ethyl cinnamate were synthesised, where sonicated samples of the latter were analysed by thin layer chromatography (TLC). Additionally, the ethyl cinnamate was purified through column chromatography with fractions analysed by TLC, whilst its identity and geometry were determined through IR and NMR analyses.
Triphenylphosphine (2.62 g, 9.99 mmol) was dissolved in toluene (20 mL), and ethyl bromoacetate (1 mL, 9.04 mmol) was added. The solution was then placed on a steam bath…