Solid acid HND-26 as a novel catalyst: Green and sustainable alternatives towards synthesis of benzyl cinnamate

High melting point and hydrophilicity of phenolic acids limit their application in lipophilic environments such as fat-containing cosmetics and foods. The esterification of the carboxyl group with fatty and aromatic alcohols has been considered as an effective way to enhance the lipophilicity of phenolic acids and thus enable better location of the antioxidant moiety into membranes and interface of emulsion systems where oxidation is expected to occur. Therefore, this study aims to evaluate the catalytic properties of six solid acids (HND-34, HND-6, HND-580, HND-2, HND-8 and HND-26) for the synthesis of benzyl cinnamate. Results show that HND-26 was the most effective solid acid to catalyse the esterification reaction of cinnamic acid with benzyl alcohol. By using response surface methodology, the influence of key experimental factors on the yield of benzyl cinnamate was investigated and the maximum yield (95.1%) was obtained under the optimized conditions (58°C, cinnamic acid/benzyl alcohol 1:20 (mol/mol), HND-26 loading 13.8% and 25 hours). The activation energy of cinnamic acid conversion with benzyl alcohol was 30.3 kJ/mol. Obtained results provide a cost-effective way of green synthesis of benzyl cinnamate and highlights the potential applications of HND-26 as an efficient catalyst for the production of phenolic acid esters with broad usage in cosmetic industry.