Copper Catalysed Oxygenation of Bis (2‐pyridyl) methane and 6‐Methyl‐bis (2‐pyridyl)methane to the Corresponding Ketones

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Abstract
The ligands (L) bis (2‐pyridyl) methane (BPM) and 6‐methyl‐bis (2‐pyridyl)methane (MBPM) form the three complexes CuL2+, CuL, and Cu2L2H with Cu2+. Stability constants are log K1 = 6.23 ± 0.06, log K2 = 4.83 ± 0.01, and log K (Cu2L2H + 2H2+ ⇌ 2 CuL2+) = −10.99 ± 0.03 for BPM and 4.56 ± 0.02, 2.64 ± 0.02, and −11.17 ± 0.03 for MBPM, respectively. In the presence of catalytic amounts of Cu2+, the ligands are oxygenated to the corresponding ketones at room temperature and neutral pH.With BPM and 2,4,6‐trimethylpyridine (TMP) as the substrate and the buffer base, respectively, the kinetics of the oxygenation can be described by the rate law with k1 = (5.9 ± 0.2) · 10−13 mol l−1 s−1, k2 = (4.0 ± 0.6) · 10−4 mol−1 ls−1, k3 = (1.1 ± 0.1) · 10−12 mol l−1 s−1, and k4 = (9 ± 2) · 10−14 mol l−1 s−1.