Reactive distillation of pyridine mixtures with an organic acid. I. Determination of the reactive distillation equilibrium

Abstract

The reactive distillation equilibrium has been experimentally determined by chromatographic analysis of the vapor phase for various mixtures of two pyridines plus an organic acid in stoichiometric deficiency in an organic solvent. Protonation of pyridines by a weak acid seems to involve ion pair formation, while protonation by a strong acid seems to result in free ion formation, and may involve a small quantity of triple molecule ions (two pyridine molecules for one acid molecule). Steric effects are not significant in such ion formation and the chemical equilibrium constant can be predicted from the pyridine pK, difference using a linear relationship. Despite the possible formation of triple molecule ions, the reactive distillation equilibrium at constant acid quantity can be reasonably well described as an ideal liquid-vapor equilibrium combined with an ideal chemical equilibrium. However, the increase of the chemical equilibrium constant with the acid quantity should be taken into account in a more refined model. On a dttermint de facon exptrimentale l'tquilibre de la distillation reactive par I'analyse chromatographique de la phase vapeur pour des mtlanges divers de deux pyridines plus un acide organique dans des conditions de dtficience stoechiomttrique dans un solvant organique. La protonation de pyridines par un acide faible semble entrafner la formation de paires d'ions, tandis que la protonation par un acide fort semble conduite h une formation d'ions libres et donner une petite quantite d'ions triples (deux moltcules de pyridine pour une moltcule d'acide). Les effets sttriques ne sont pas importants dans une formation d'ions de ce type et la constante d'tquilibre chimique peut Ctre prMite ii partir de la difftrence pK, de la pyridine par une relation lintaire. Malgrt la formation possible d'ions triples, I'tquilibre de la distillation rtactive avec des quantitts d'acide constantes peut Ctre raisonnablement dtcrit c o m e un tquilibre liquidevapeur idtal combint ? I un tquilibre chimique idtal. Cependant, I'augmentation de la constante d'tquilibre chimique avec la quantitt acide devrait stre prise en compte dans un modkle plus precis.

Isobaric low-pressure vapor–liquid equilibrium data of the system monochloroacetic acid+dichloroacetic acid+diethylene glycol dipentyl ether and the constituent binary systems

“…As a result, DCA is more retained in the liquid phase, and the relative volatility increases [10]. The application of complexing agents in distillation columns is also often reported as reactive extractive distillation or complex extractive distillation [12][13][14][15]. From our extractant screening study, diethylene glycol dipentyl ether (DGDP, see Fig.…”

Reactive Extraction as an Intensifying Approach for the Recovery of Organic Acids from Aqueous Solution: A Comprehensive Review on Experimental and Theoretical Studies

“…The importance of biological production of organic compounds is growing with increased demands and needs for adapted downstream processes to increase production rates. Various methods such as precipitation, − chromatography, , ion-exchange, − adsorption, − distillation, , crystallization, , membrane separation, − and liquid extraction − have been reported for the separation of high valued organic acids from aqueous solutions (waste streams/fermentation broths). These separation and recovery methods, have some advantages and disadvantages in their operations.…”

Reactive Extraction of Gluconic Acid Using Trioctylamine in Different Diluents

“…Currently, the available technologies for separation and purification of carboxylic acids are electrodialysis, anion exchange 3, 4, adsorption 5, direct distillation 6, ultrafiltration, membrane processes 7, and solvent extraction 8. Most of these techniques are not suitable, e.g., because of large amounts of separation agents, high energy consumption, and significant waste production 9.…”