The role of the complexes of diphenylmethanimine (lm) with copper chlorides, CuClelm (1), CuCl e21m(2), CuC12elm(3) and CuC12.21m(4) in the oxidative coupling of lm has been studied.
Benzophenone azine (Az) was obtained in the yield of 70% at 1200C by the addition of cuprous chloride. Qxygen is necessary to form Az and in the atmosphere of nitrogen one obtain not Az but complex(Z). Cupric chloride was less effective for the formation of Az (yield 5%)
It was shown that complex(2) and (4) release lm reversibly to form (1) and (3), respectively. In reference to the formatiep of (1) by the thermal decomposition of (4), complcx (1) may be regarded as an effective intermediate for the formation of Az. The presumption was confirmed by the formation of Az from lm by the addition of the catalytic amounts of any of complexes (1)N(4), in which (1) is most effective (Table 3).
Complex(1) in chloroform solution absorbed oxygen to form complex(5), containing about two atoms of oxygen per (1) (Table 2). Although the atomic ratie of copper and chlorine in (5) is unity, the former is revealed to be divalent. ln the oxidative ceupling of lm in a condition of cucl/Im 1/1, complex(5)was obtained as a main product at the time when the free lm just disappeared. The continued supply of oxygen resulted in conversion (5) to Az. (Table 1).