Heterogeneous Kinetics of the Dissolution of an Inorganic Salt, Potassium Carbonate, in an Organic Solvent, Dimethylformamide

Abstract

Understanding the mechanisms of solid-liquid systems is fundamental to the development and operation of processes for the production of agrochemicals and pharmaceuticals. The use of a strong inorganic base in an organic solvent, typically, potassium carbonate in dimethylformamide, is often used to facilitate the formation of a required anionic organic nucleophile. In this paper, the dissolution kinetics of potassium carbonate in dimethylformamide at elevated temperatures is studied in the presence of ultrasound, as revealed via monitoring of the deprotonation of 2-cyanophenol by dissolved K2CO3. Two independent experimental methods were employed; the loss of 2-cyanophenol was detected electrochemically at a platinum microdisk working electrode, and the formation of the 2-cyanophenolate anion was monitored via UV/visible spectroscopic analysis. The results were modeled by fitting the experimental data to a theoretical model for the surface-controlled dissolution of solid particles. The dissolution rate constant, k, for the dissolution of K2CO3 in DMF was found to have a value of (1.3 +/- 0.2) x 10(-7) mol cm(-2) s(-1) at 100 degrees C, and the activation energy for the dissolution was 44.2 +/- 0.4 kJ mol(-1) over the temperature range of 70-100 degrees C studied.

Surface-controlled dissolution rates: a case study of nanoceria in carboxylic acid solutions

“…All of these models showed generally poor correspondence. There was good correspondence between data and prediction when a model for surface-controlled dissolution of solid particles 43, 53 was applied to the bath data. This model links the rate of solid dissolution from a spherical particle to its current surface area.…”

“…where n 1 (t) is the number of atoms in a nanoparticle with diameter, d 1 (nm); k is the dissolution rate constant (Ce atoms/nm 2 -h), and S 1 (t) is the surface area of the particle (nm 2 ) 43, 53 . The present study used nanoceria with an average diameter of ~ 4 nm, so the number of Ce atoms in the nanoparticle was selected as the metric.…”

Comparative solubilisation of potassium carbonate, sodium bicarbonate and sodium carbonate in hot dimethylformamide: application of cylindrical particle surface-controlled dissolution theory

“…In previous papers we reported the surface-controlled dissolutions of KHCO 3 and K 2 CO 3 in dimethylformamide (DMF) at elevated temperatures. Two theoretical models have been developed, the first for the dissolution of spherical solid particles 16,17 and secondly for the dissolution of cylindrical particles 18 A comparison between the theories was used to show the influence of particle shape on the dissolution kinetics of a solid and hence the importance of knowing the shape of the individual solid particles for realistic modelling of their dissolution. Both surface-controlled dissolution models were successfully applied to experimental results for the dissolution of KHCO 3 in DMF and values for the dissolution rate constant, k, determined.…”

Evaluation of Poorly Soluble Drugs’ Dissolution Rate by Laser Scattering in Different Water Isotopologues

“…Thus, the aqueous solution of topiramate belongs to the coarse particle dispersion system. The particles of the dissolved substance retain all the properties of the phase, so its solution is a heterogeneous system [39][40][41]. The heterogeneous dissolution process of substances is limited by diffusion, adsorption, and desorption according to Fick's law and the dissolution of the Nernst-Shchukarev equation using the following formula [42]:…”