Title:A New Approach to Synthesis of Benzyl Cinnamate: Kinetic and Thermodynamic Investigation
Volume: 10
Issue: 1
Author(s): Gao-Ying Zhi, Xiao-Bing Li, Yun Wang, Li Han and Dong-Hao Zhang*
Affiliation:
- College of Pharmaceutical Science, Hebei University, Baoding, 071002,China
Keywords:
Enzymatic synthesis, benzyl cinnamate, kinetic model, ping-pong Bi-Bi mechanism, substrate inhibition, thermodynamics.
Abstract:
Background: Benzyl cinnamate is widely used in many fragrance compounds. The traditional
methods to obtain benzyl cinnamate, including chemical synthesis or extraction from
leaves, have many drawbacks. Recently, lipase-catalyzed synthesis of benzyl cinnamate has provided
us with a promising alternative due to its high catalytic efficiency, mild reaction conditions,
and green and environmentally friendly process. In this work, the purpose is to investigate the kinetics
and thermodynamics of enzymatic synthesis of benzyl cinnamate.
Objective: The objective of the current study was to investigate the kinetics and thermodynamics of
the enzymatic synthesis of benzyl cinnamate.
Results: The results showed that the reaction followed the Ping-Pong mechanism leading to substrate
inhibition. Furthermore, the kinetic and thermodynamic parameters were estimated. The inhibition
constant KiB decreased with temperature enhancement, implying that the inhibition of benzyl
alcohol on lipase could be depressed at high temperatures. Moreover, the activation energy of
the first-step reaction (52.46 kJ/mol) was much higher than that of the second-step reaction (12.97
kJ/mol), demonstrating that the first-step reaction was the rate-limiting reaction. The esterification
process was found to be endothermic, with an enthalpy value (ΔH) of +55.7 kJ/mol and entropy
value (ΔS) of +170.2 J/mol K, respectively. Based on the change of Gibbs free energy (ΔG), enzymatic
esterification of cinnamic acid changed from non-spontaneous to spontaneous reaction when
temperature was raised to above 53ºC.
Conclusion: This obtained information could be utilized to optimize the biosynthesis of benzyl
cinnamate.
