Enhanced stability of potassium solutions in tetrahydrofuran containing 15-crown-5

Abstract

The process of potassium metal dissolution in tetrahydrofuran containing 15-crown-5 and the properties of the solution were studied. The changes in concentration of potassium anions and electrons as a function of time were determined by means of 39K NMR and ESR spectroscopies. Enhanced stability of the solution with 15-crown-5 relative to that containing 18-crown-6 or 12-crown-4 was revealed.

Decomposition of vinyl ethers by alkalide K−, K+(15-crown-5)2 via organopotassium intermediates

“…The fractions boiling at 94, 70°C /20 mm Hg, and 112°C/10 mm Hg were collected, respectively. A 0.1 M K À , K þ (15-crown-5) 2 tetrahydrofuran solution was prepared as described in [21].…”

“…4.6. Benzyl butyl ether (16), benzyl phenyl ether (6), and tetraethylene glycol benzyl vinyl ether (7) Their GC-MS and NMR spectra have been reported in [6,7,14], respectively.…”

“…That led to the generation of new organopotassium compounds being intermediate products in those systems. They were generally unstable and underwent various fast reactions, e.g., with crown ether or with the substrate [16]. Some of them eliminate potassium phenoxide [5] or unsaturated hydrocarbons, e.g., ethylene [12,14] or cyclohexene [15].…”

Model Studies Towards Alternative Cross-Linking of Unsaturated Polyesters

“…However, in presence of air, the PdCl 2 (PPh 3 ) 2 /CuI/amine mixture is a very effective system for the catalytic oxidative homo-coupling of terminal alkynes to the corresponding diynes [13] and thus, the target compounds 4 were obtained in very high yields (94-96%) [14]. Control runs confirmed that the combination of Pd, Cu and O 2 is crucial for the success of the coupling reaction.…”

Stepwise Two-Electron-Transfer Reduction of Cyclic Ethers and Lactones with Alkalide K-, K+(15-Crown-5)2

“…This new concept of the reaction mechanism inspired us to examine that phenomenon in other systems. Alkalide K , K + (15-crown-5) 2 in tetrahydrofuran solution was used in those experiments as a good source of potassium anions because of its enhanced stability at ambient temperature in comparison to alkalide K , K + (18-crown-6) [25].…”