1967 Volume 9 Pages 45-52
A kinetic study has been made of the synthesis of o- and p-anisaldehyde from anisole-BF3 complex and CO in hydrogen fluoride solution.
In the preliminary investigation a new white complex was obtained below -60°C, the composition of which was 1 mole anisole-2 moles BF3-1 mole HF with a m. p. of -60°C. The apparent equilibrium constant for the complex formation has been determined to be 219 at 0°C on the assumption of the existence of o- and p-complex of σ-type.
As to the reaction of anisole with CO, the conditions enabling the liquid phase reaction rate-determining were found to be: a charge ratio of Anisole/HF<30, a stirring speed above 750rpm and an operational temperature below 60°C; the latter being essential to prevent side reactions leading to the formation of tarry matter.
The rate of each o- and p-aldehyde formation is of the first order with respect to the dissolved CO and the complex respectively. The apparent rate constants are 6.67×10-3 (kg-1cm2•min-1) for o- and 4.23×10-3 for p-aldehyde formation at 40°C and the apparent activation energies 9kcal•mole-1 for both products.
Compared with the rates of the same reaction with toluene and m-xylene, the rate constant of anisaldehyde formation is much smaller.
