Synthesis and Characterization of Hydroxycinnamoyltartaric Acids Relevant to Winegrape Polyphenolic Analysis

Hydroxycinnamic acids (HCAs) and their esters naturally occur in plant materials, fruits, and vegetables. Their concentration determines their functionality as antioxidants, pest deterrents, or flavor components, making the accurate identification essential for analysis. While all free hydroxycinnamic acids are available as analytical standards, only one of the tartrate esters can be purchased commercially. The scope of this study was to develop and optimize a synthesis procedure to produce esters from ferulic, p -coumaric, and caffeic acids with tartaric acid and tentatively characterize the reaction products using HPLC-DAD. With this method, between two and four esters can be produced and separated via chromatography, depending on the hydroxycinnamic acid used. The best yields are achieved with p -coumaric acid, reaching a 75% conversion rate. All products were characterized using their UV spectrum and are identified via retention time and spectral information. This will help our understanding of the presence, reactivity, and impact of these important molecules.