Application of the aldehyde reactions for the endpoint detection in the catalytic thermometric titration of acids

Abstract

Exothermic reaction of formaldehyde polymerization in alcoholic medium which is catalyzed by diluted solutions of strong bases was used for catalytic thermometric endpoint indication in titrations of organic acids. The amounts of 7.80–23.10 mg of various organic acids were determined with a relative standard deviation less than 0.9%. The developed method was successfully applied also to determination of free acid content (formic acid) in aqueous solutions of formaldehyde of various manufacturers. Also investigated were the possibilities of the application of two new indicator reactions in catalytic thermometric titrimetry: the exothermic reactions of aldolic addition of both benzaldehyde and acetophenone, and benzaldehyde and methylethylketone, which are catalyzed in alcoholic medium by diluted solutions of strong bases. The influence of concentration of indicator reaction components, the solvent and the titrant, on the shape of catalytic thermometric curves was explored. The obtained results were compared to those of potentiometry and other standard methods.