Some Studies in the System Zinc Acetate--Hydrogen Chloride--Acetic Acid

Abstract

In previous papers from this Laboratory and elsewhere, numerous similarities have been pointed out between solutions of acids, bases and salts in anhydrous acetic acid on the one hand, and familiar aqueous systems on the other. As yet, however, few acetic acid systems containing analogs of so-called acid or basic salts have been described. It is obvious that the anhydrous ternary systems zinc chloride-zinc acetate-acetic acid and zinc chloride-hydrogen chloride-acetic acid might be regarded as analogous, respectively, to zinc chloride-zinc oxide-water and zinc chloride-hydrogen chloride-water ; and that in the former case basic salts might be expected to occur, in the latter case, acid salts.The study of equilibria between solid and liquid phases in binary solutions of zinc chloride in acetic acid presents extraordinary difficulties because of the extremely high viscosity of the concentrated solutions, which, as previously noted by Reddelien,' form thick sirups a t ordinary temperatures. The same difficulty arises also in ternary solutions containing hydrogen chloride. Hence, except for a rough determination of the solubility of zinc chloride, the quantitative data obtained for these "neutral" and "acid" systems are limited to solutions from which acetic acid separates as solid phase. It was found possible, however, to investigate the '(basic') system over a considerable concentration range a t 30°, and to isolate two "basic" salts in the solid state. MethodPreparation of Materials.-Pure anhydrous acetic acid and zinc acetate were prepared as described in previous papers of this series.2Because of the difficulty of preparing and handling anhydrous zinc chloride, no attempt was made to use the solid salt, except in preliminary qualitative experiments. It was found, however, that a solution of zinc chloride in acetic acid might be obtained readily by the passage of dry hydrogen chloride over dry zinc acetate; a metathetic reaction takes place, which may be regarded as a neutralization Zn(C2HaOz)z + 2HC1 = 2HC~Hs02 + Znfi + 2C1-Gaseous hydrogen chloride, prepared in the usual manner, was dried by passage through two towers filled with glass (1) Reddelien, Ann., 388, 190 (1912). (2) Davidson and McAllister, THIS JOURNAL, 62, 512, 519 (1030).wool which had been moistened with anhydrous sulfuric acid. The gas was then passed into a flask containing zinc acetate (suitably protected from atmospheric moisture), and the mixture was warmed, with gentle agitation; gradual liquefaction resulted, in accordance with the above equation. After all the solid had disappeared, the solution, which contained a t this stage a slight excess of hydrogen chloride, was analyzed both for chlorine and for zinc; the former was determined gravimetrically, the latter by titration against potassium ferrocyanide solution, with uranyl nitrate solution as an external indicator. From these data the amount of excess hydrogen chloride was calculated, and zinc acetate was added to the solution in quantity just sufficient to react with this excess. Thus...

Preparation and Characterization of Zinc(II)-Based Lewis/Brønsted Acidic Deep Eutectic Solvents

“…Notably, the combination of ZnCl 2 and acetic acid was known and characterized in 1939 [34] and used in different contexts [35,36]. This mixture, in fact, has peculiar properties and presents advantages with respect to the common use of the catalyst Zn acetate, as Zn acetate lacks any Brønsted acidity, and the presence of chloride ions of ZnCl 2 could influence the solubility of many chemical species through the instauration of chemical equilibria or weak interactions.…”