Hydrogenation of 1,10-phenanthroline

Abstract

A reductive dehalogenation of substituted 1,lO-phenanthrolines has also been n~t e d .~~~ Catalytic hydrogenation of 1,lO-phenanthroline with Raney nickel catalyst by a method similar to that adopted by Searles and Warrens for the reduction of 4,7-phenanthroline (2) afforded 1,2,3,4-tetrahydro-l,10-phenanthroline (1) in 80 % yield when the hydrogenation was carried out at 58 lb/sq in pressure at 20" for 40 h. There was no evidence for the formation of the 5,6-dihydro derivative analogous to (3) although Searles and Warrens obtained both (4), in 40 % yield, and (3), in 44 % yield, from the similar reduction of 4,7-phenanthroline. The structure of (1) was confirmed by elementary analyses and n.m.r. spectroscopy and by characterization of the derived hydrobromide salt. Hensen and Trobsl did not analyse compound (1) but characterized it by way of the dihydrochloride salt and the picrate. The tetrahydro-1,lOphenanthroline (1) afforded 1-acetyl-1,2,3,4,-tetrahydro-1,lO-phenanthroline by

On the quantitative recycling of Raney–Nickel catalysts on a lab-scale

“…There are also asymmetric hydrogenations of heteroarenes (quinolines) known using iridiumphosphine complexes. 9 Under an atmosphere of pressurized hydrogen, Raney-Nickel proved to be a highly efficient catalyst for the selective hydrogenation of our model system 2,9-dimethyl [1,10]phenanthroline (Scheme 1). 10 Freshly prepared Raney-Nickel showed significantly more activity than the commercial catalyst.…”

“…9 Under an atmosphere of pressurized hydrogen, Raney-Nickel proved to be a highly efficient catalyst for the selective hydrogenation of our model system 2,9-dimethyl [1,10]phenanthroline (Scheme 1). 10 Freshly prepared Raney-Nickel showed significantly more activity than the commercial catalyst. 11 Although the resultant octahydrophenanthroline has been isolated in high yield (.98%), we wondered whether recycling of the catalyst could be effected in order to improve the economic and ecological efficiency of this protocol.…”

“…12 We then put this operationally simple immobilization technique to a 'real world' test. 2,9-Dimethyl [1,10]phenanthroline (neocuproine) was hydrogenated in the presence of 10 mol% Raney-Nickel under standard conditions in a high pressure reactor (27 bar H 2 , 100 uC, 16 h, EtOH) to give the resultant octahydrophenanthroline in quantitative yield.…”

“…15 Representative procedure: A 50 mL Parr 1 high pressure reactor was charged with [1,10]-phenanthroline (150 mg, 0.833 mmol) and abs. ethanol (6 mL).…”

Metalation/De-metalation as a Post-Gelation Strategy to Tune the Mechanical Properties of Catenane-Crosslinked Gels

“…Although the internal olefin of 11 could also potentially react during the ring closing (iv) step to form the [2]catenate, hydrogenation was not performed as it was often lower yielding because of hydrogenation of the N to C double bonds in the phen ligand. 23 Compound 12 was deprotected using trifluoroacetic acid (13, Scheme S13), and the functional crosslinker was generated by adding acryloyl chloride to obtain catenane 14 in 90% yield. The purity of 14 was confirmed by 1 H NMR and HPLC (Fig.…”