3,4,5-Tri-dodecyloxybenzoic acid: optimisation and scale-up of the synthesis

The synthesis of tris-O-dodecyl-gallic acid [3,4,5-tris(dodecyloxy)benzoic acid] - a versatile building block for org. liq. cryst. materials - has been selected for fine chem. scale-up. A large-scale procedure of the alkylation of Me gallate with dodecyl bromide was optimized with exptl. design techniques. Apart from the solvent effect, the temp., phase-transfer catalyst, stirring speed, and amt. of base were found to be most significant for the reaction rate. Reaction calorimetry revealed no excessive exothermic reaction steps in the process. Reaction kinetics on the alkylation reaction was studied as a function of particle size distribution of the base, potassium carbonate, and formation of carbon dioxide. Combination of all exptl. results has debouched into a master recipe for kilogram-scale synthesis in a 10 dm3 fully automated (semi)batchwise operated reactor. [on SciFinder (R)]