Fine Chemicals from Lignosulfonates. 2. Synthesis of Veratric Acid from Acetovanillon

An optimisation study based upon experimental data obtained from multivariate statistical experimental design and modelling for the haloform reaction used for synthesis of 3,4-dimethoxybenzoic acid from 3,4-dimethoxy acetophenone is reported. It is shown how the different controllable process variables influence both the yield of 3,4-dimethoxybenzoic acid and the formation of the side product 2-chloro-4,5-dimethoxybenzoic acid. Two predictive multivariate models are derived and used to predict optimal conditions for the oxidation process. Using these models, a yield of 90% (from approximately 60%) of desired product is achieved. Moreover, the model describing the formation of the side-product can in fact also be applied to optimise a procedure for obtaining 2-chloro-4,5-dimethoxybenzoic acid in substantial quantities. One experiment showed that the side-product could be formed in a quantity of >20%.