Primary and secondary nitro compounds react with dioxygen in the presence of copper metal and N ligands such as N,N,N′,N′-tetramethylethylenediamine (tmeda), 2,2′-bipyridine (bpy), and 1,10-phenantroline (phen) in various solvents to form aldehydes or ketones. More coordinating solvents as well as donor N ligands accelerate the reaction remarkably. The oxygenolysis of 2-nitropropane (NPH) in the presence of copper and tmeda in DMF results in acetone and acetone oxime. The amount of tmeda influences the chemoselectivity, higher tmeda concentrations preferentially lead to the formation of the oxime. The kinetics of the reaction, measured at 90 °C, resulted in a rate equation of first-order dependence on copper and dioxygen and second-order dependence on 2-nitropropane. The rate constant, activation enthalpy, and entropy at 363.16 K are as follows: kcat = (5.37 ± 0.34) × 10-2 Mol-3 dm9 s-1, Ea = 131 ± 4 kJ mol-1, ΔH‡ = 127 ± 4 kJ mol-1 and ΔS‡ = 80 ± 13 J mol-1 K-1. The catalytically active intermediates CuII(NP)2(tmeda) and CuII(NO2)2(tmeda) in the catalytic cycle were isolated and their structures determined by X-ray crystallography. The kinetics of the stoichiometric oxygenation of CuII(NP)2(tmeda) to CuII(NO2)2(tmeda) and acetone resulted in the overall second-order rate equation with a rate constant, activation enthalpy, and entropy at 313.16 K of ks = 0.46 ± 0.02 mol-1 dm3 s-1, Ea = 38 ± 1 kJ mol-1, ΔH‡ = 35 ± 1 kJ mol-1 and ΔS‡ = -142 ± 13 J mol-1 K-1, respectively.
|Number of pages||10|
|Journal||European Journal of Inorganic Chemistry|
|Publication status||Published - Jan 1 2002|
- Copper nitronates
ASJC Scopus subject areas
- Inorganic Chemistry