Premium
Kinetics and Mechanism of the Copper‐Catalysed Oxygenation of 2‐Nitropropane
Author(s) -
BaloghHergovich Éva,
Gréczi Zoltán,
Kaizer József,
Speier Gábor,
Réglier Marius,
Giorgi Michel,
Párkányi László
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200207)2002:7<1687::aid-ejic1687>3.0.co;2-q
Subject(s) - chemistry , reaction rate constant , enthalpy , medicinal chemistry , entropy of activation , kinetics , copper , catalysis , stoichiometry , enzyme kinetics , inorganic chemistry , organic chemistry , active site , physics , quantum mechanics
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: k cat = (5.37 ± 0.34) × 10 −2 mol −3 dm 9 s −1 , E a = 131 ± 4 kJ mol −1 , Δ H ‡ = 127 ± 4 kJ mol −1 and Δ S ‡ = 80 ± 13 J mol −1 K −1 . The catalytically active intermediates Cu II (NP) 2 (tmeda) and Cu II (NO 2 ) 2 (tmeda) in the catalytic cycle were isolated and their structures determined by X‐ray crystallography. The kinetics of the stoichiometric oxygenation of Cu II (NP) 2 (tmeda) to Cu II (NO 2 ) 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 k s = 0.46 ± 0.02 mol −1 dm 3 s −1 , E a = 38 ± 1 kJ mol −1 , Δ H ‡ = 35 ± 1 kJ mol −1 and Δ S ‡ = −142 ± 13 J mol −1 K −1 , respectively. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)