Synthesis of 6,7-Dihydro-1H,5H-pyrazolo[1,2-a]pyrazoles by Azomethine Imine-Alkyne Cycloadditions Using Immobilized Cu(II)-Catalysts.

A series of 12 silica gel-bound enaminones and their Cu(II) complexes were prepared and tested for their suitability as heterogeneous catalysts in azomethine imine-alkyne cycloadditions (CuAIAC). Immobilized Cu(II)-enaminone complexes showed promising catalytic activity in the CuAIAC reaction, but these new catalysts suffered from poor reusability. This was not due to the decoordination of copper ions, as the use of enaminone ligands with additional complexation sites resulted in negligible improvement. On the other hand, reusability was improved by the use of 4-aminobenzoic acid linker, attached to 3-aminopropyl silica gel via an amide bond to the enaminone over the more hydrolytically stable N-arylenamine C-N bond. The study showed that silica gel-bound Cu(II)-enaminone complexes are readily available and suitable heterogeneous catalysts for the synthesis of 6,7-dihydro-1H,5H-pyrazolo[1,2-a]pyrazoles.

Synthesis of Optically and Redox Active Polyenaminones from Diamines and α,α'-Bis[(dimethylamino)methylidene]cyclohexanediones.

New oligo- and polyenaminones with Mw ~ 7-50 KDa were prepared in high yields by transaminative amino-enaminone polymerization of regioisomeric bis[(dimethylamino)methylidene]cyclohexanediones with alkylene and phenylenediamines. The polymers obtained are practically insoluble in aqueous and organic solvents and exhibit film-forming properties, UV light absorption at wavelengths below 500 nm, and redox activity. These properties indicate a promising application potential of these polymers, which could find use in optical and optoelectronic applications and in energy storage devices.

Scalable Synthesis of Salt-free Quaternary Ammonium Carboxylate Catanionic Surfactants.

Surfactants in commercial products commonly contain catanionic mixtures thus many studies of aqueous surfactant mixtures have been carried out. However, hardly any studies have been dedicated to pure catanionic surfactants often termed salt-free catanionic surfactants. One of the difficulties is in acquirement of samples with required purity due to difficult separation of these compounds from inorganic salts. In this work we present an alternative method of synthesis using dimethyl carbonate as the alkylating agent in order to obtain alkyl trimethylammonium alkanecarboxylates with medium alkyl chain lengths (6-10).