Bis(a-camphorquinone dioximato)cobalt is prepared from Cobalt(II) Chloride hexahydrate and the corresponding isomer of camphorquinone dioxime (cqd) (from optically active natural camphor) in ethanol with addition of an aqueous solution of NaOH under nitrogen or argon.1 This complex is best when freshly prepared before use under nitrogen or preferably under argon. The starting material, L-camphor, is easily obtained in optically pure form.
The dry solid Bis(a-camphorquinone dioximato)cobalt must be kept under nitrogen or argon, preferably in the cold. The solution of the catalyst in organic solvents such as benzene, acetone, ethyl acetate, hexanes, or acetophenone deteriorates on standing even under nitrogen. Therefore use just after preparation is recommended.
1. Nakamura, A.; Konishi, A.; Tatsuno, Y.; Otsuka, S. JACS 1978, 100, 3443
