Speciation Behavior of Copper(II) Acetate in Simple Organic Solvents – Revealing the Effect of Trace Water

Abstract

Copper(II) acetate is frequently used as a catalyst for bondforming reactions in organic synthesis. Unlike aqueous solutions, in which complete heterolysis to CuOAc + (aq) and AcO -(aq) prevails at low concentrations, it is clear that copper(II) acetate shows a large degree of aggregation in typical organic solvents. Here, the speciation behavior of Cu(OAc) 2 in organic solvents is probed by electrospray ionization mass spectrometry (ESI-MS), which reveals an extensive clustering of copper acetate species to form ions of the general composition [Cu n (X) 2n-1 ] + and [Cu n (X) 2n+1 ] -(X = OAc and [a]

Selective Synthesis of Tetrasubstituted Olefins by Copper‐Mediated Acetoxythiolation of Internal Alkynes: Scope and Mechanistic Studies

“…In the solid state, it occurs as a dinuclear dihydrate, [Cu(OAc) 2 ] 2 ⋅ (H 2 O) 2 , with a paddle‐wheel structure . Recent electrospray ionization mass spectrometry (ESI‐MS) studies of its speciation behavior in organic solvents such as methanol support extensive aggregation of Cu(OAc) 2 in such media . Accordingly, we modeled the Cu II reagent as dimeric [Cu(OAc) 2 ] 2 ⋅ (H 2 O).…”

“…[64] Recent electrospray ionization mass spectrometry (ESI-MS) studies of its speciationb ehavior in organic solvents such as methanol support extensive aggregation of Cu(OAc) 2 in such media. [65] Accordingly,w em odeledt he Cu II reagent as dimeric[ Cu-(OAc) 2 ] 2 ·(H 2 O). The same description was employed in ar ecent theoreticals tudy of oxidative coupling reactions.…”

Aqueous Spray Pyrolysis of Cu2O Films: Influence of Reducing Agent and Acetic Acid Addition

“…The dissolution of copper acetate in an aqueous solution yields either Cu 2+ ions or Cu 2+ ‐complexes with acetate and water ligands, depending on the pH value . Therefore, it is necessary to reduce the Cu 2+ ions to their +I oxidation state to form a Cu 2 O film.…”

“…The dissolution of 0.025 M CuAc 2 salt in water yields a solution pH of 5.5 that is close to the region where Cu(OH) 2 starts to precipitate . To decrease the pH value below 3, a region where copper ions are highly soluble in the form of Cu 2+ or as copper‐hydro‐acetate complexes, a minor amount of acetic acid was added to all solutions described above.…”

“…Since Cu 2+ could, depending on the solution composition, precipitate (K sp =2.2×10 −20 ) in the form of Cu(OH) 2 in minor acidic (∼pH=5.5) aqueous solutions, a small volume of acetic acid was added to the solution. The effect of the altered pH value, accompanied by the presence of additional acetate ligands that can complex Cu 2+ ions, was investigated for solutions containing different reducing agents (D‐glucose, glycerol or D‐sorbitol).…”