Chemical recycling of polyenaminones by transamination reaction via amino–enaminone polymerisation/depolymerisation

Efficient Chitosan/Nitrogen-Doped Reduced Graphene Oxide Composite Membranes for Direct Alkaline Ethanol Fuel Cells

“…Graphitized N-polyenaminone (N-pEAO) was synthesized in a two-step reaction employing a wet chemistry bottom-up approach. In the first step, polyenaminone (4ca) was synthesized by acid-catalyzed amino–enaminone “click” polymerization reaction [ 14 , 18 ]. Such polymer with inherently layered morphology ( Figure S1 ) was then, in a second step, pyrolyzed in an inert atmosphere to yield graphitic N-polyenaminone (N-pEAO).…”

“…Poly(2-(3-aminopropenoyl)-6-{3-[(1,3-phenylene)amino]propenoyl}pyridine) (4ca) was prepared following the general literature protocol for the synthesis of a related polyenaminones [ 14 ]. A mixture of (2 E ,2’ E )-1,1’-(pyridine-2,6-diyl)bis(3-(dimethylamino)prop-2-en-1-one) (2c) (273 mg, 1 mmol), 1,3-phenylenediamine dihydrochloride (3a) (181 mg, 1 mmol), and methanol (10 mL) was shaken on an orbital shaker (400 r.p.m.)…”

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

“…If poor reusability of catalyst 5f is explainable by decomplexation of copper ions from the heterogeneous ligand 4f , then reusability should be improved by stronger coordination of copper(II) to the ligand. Therefore, we decided to address the reusability issue by attaching stronger coordinating acacen ligands 9a , b [ 27 , 50 , 51 , 52 , 53 , 54 , 70 ] and pyridine-enaminone ligands 9c [ 71 ] to 3-aminopropyl silica gel ( 3 ).…”

“…Thus, treatment of 9a and 9b with 3 in methanol at room temperature afforded the immobilized acacen ligands 10a and 10b , which were subsequently reacted with Cu(OAc) 2 ·H 2 O in methanol to furnish the desired immobilized Cu–acacen complexes 11a and 11b ( Scheme 3 ). To obtain pyridine-type catalyst 11c , bis-enaminone ligand 9c [ 71 ], was reacted with 3-aminopropyl silica gel ( 3 ) to give silica gel-bound ligand 10c , followed by treatment with Cu(OAc) 2 ·H 2 O in methanol to furnish the copper complex 11c ( Scheme 3 ). Absorption bands at around 1600 cm −1 (C = O/C = N) in the IR spectra of compounds 11a – c and the combustion analyses for compounds 11a – c were in line with attachment of copper–enaminone complexes to 3 (For characterization details see the Supporting Information ).…”

“…Active methylene compounds 1a – g , 3-aminopropyl silica gel ( 3 ) (for preparative chromatography, 40–63 µm, 0.9 mmol/g amino groups, pore size ~9 nm), 4-aminobenzoic acid ( 12 ), Cu(OAc) 2 ·H 2 O, N,N -dimethylformamide dimethylacetal (DMFDMA, for synthesis, ≥96%), tert -butoxy-bis(dimethylamino)methane (TBDMAM, technical grade), and 1,1′-carbonyldiimidazole (CDI) are commercially available (Sigma-Aldrich). Enaminones 2a [ 72 ], 2b [ 73 ], 2c [ 74 ], 2d [ 75 ], 2e [ 76 ], 2f [ 77 ], and 2g [ 78 ], bis-enaminones 9a , 9b [ 70 ], and 9c [ 71 ], and azomethine imines 6a , f [ 79 ], 6b , e [ 80 ], 6c [ 81 ], and 6d [ 82 ] were prepared following the literature procedures.…”