The Synthesis Of Anisaldehyde By Indirect Electrochemical Oxidation From Anethole

The indirect electrochemical oxidation of anethole to anisaldehyde with Ce⁴⁺/Ce³⁺ as redox mediator system was studied in this thesis. The electrochemical and chemical steps were investigated separately in order to determine operating conditions providing a high current efficiency and high yield.The electrochemical behavior of Ce⁴⁺/Ce³⁺in sulfuric acid on platinum electrode was investigated with conventional ways, such as linear sweep polarization and cyclic voltammogram, etc. The results of experiments show that the electrode reaction is controlled by mixing process of diffusion and charge-tranfer, and the electrochemical reaction of Ce⁴⁺/ Ce³⁺ on platinum electrode is quasi reversible.The electrochemical oxidation experiments of Ce³⁺were performed in a single chamber cell, and the optimum conditions are as follow: a platinum plate as anode and a stainless steel plate as cathode in the electrolyte solution containing 1 molL^-1 H₂SO₄ + 0.15 mol·L^-1Ce₂(SO₄)₃ through the electro-quantity of 1.5 F·mol^-1 using the current density of 14 mA-cm^-2 and the area ratio of cathode to anode 1:6 at the temperature of 30℃. Under this optimum conditions the electrolytic yield of Ce⁴⁺ is 88% and the current efficient of 59% is obtained using galvanostatic mode. After the regeneration cycle use of the redox mediator for 10 times the electrolytic yield of 87% for the oxidation of Ce⁴⁺ can still be obtained.The optimization of anisaldehyde s ynthesis conditions was carried out by reviewing the effects of factors on the yield of anisaldehydethrough orthogonal tests and single-factor tests. The optimized result is the synthesis operation in 0.5 mol-L"1 sulfuric acid solution in which ratio between Ce4+ and anethole is 3:1 at the temperature of 30°C in the presence of benzene. Under the optimum conditions, the yield of reaction reaches 90%. In addition, the kinetics on the oxidation reaction of anethole to anisaldehyde by Ceric Sulfate was studied. The rate constants of anethole oxidation to anisaldehyde by Ceric Sulfate at different temperature (15-35°C) were measured. The rate equation, d[As]/dt = k[At]-[Ce4+], and apparent activation energy (51.12 kJ-mol"1 ) of the reaction were found.