Kinetics of transesterification with various alkyl acetates for β-citronellyl acetate synthesis

• The structure of alkyl acetate influenced the conversion of β -citronellol. • The structure of alkyl acetate influenced the selectivity to β -citronellyl acetate. • The composition and the amounts of by-products depended on the mechanism. β -Citronellyl acetate was synthesised by acid-catalyzed transesterification of β -citronellol with various alkyl acetates. p -Toluenesulfonic acid was chosen as the acid catalyst. We studied several effects on transesterification, and the most interesting effect was the structure of alkyl acetate. When linear acetates were used, transesterification was retarded with the length of the alkyl chain. Values of reaction rate constant were in the range from 0.273 to 0.180 l/mol/h at 50 °C with real selectivity. The situation was different for branched alkyl acetates. The behaviour of isobutyl acetate was similar to linear acetate (same value of the reaction constant). Isopropyl acetate reacted more slowly than we expected. When tert ‑butyl acetate was used, the alkyl cleavage mechanism of generated undesired β -citronellyl tert ‑butyl ether and only 67 % selectivity to β -citronellyl acetate was obtained. When methyl acetate was used, the activation energy (50 °C, presumed 100 % selectivity) was 48.9 kJ/mol. The contributions were approximately 2.5 kJ/mol per 1C and 23 kJ/mol per 1CH3. These findings provide valuable insights into the impact of alkyl acetate structure on transesterification efficiency and significant role on kinetics and selectivity.