Mechanism of the Tübingen photooximation reaction
INTRODUCTION Towards the end of the second World War we attempted the preparation of cyclohexanone-oxime (an important intermediate in the synthesis of Perlon) starting from cyclohexane—that means benzene as the basis, by avoiding the then scarce phenol basis. We remembered the experiments of E. V. Lynn who as early as 1919 had obtained a mixture of various nheptanone-oximes in small yields when he exposed n-heptane together with nitrosyl chloride to sunlight. Furthermore, we wanted to avoid the separate preparation of the offensive nitrosyl chloride. After overcoming the troubles of the postwar period, we were able to develop a special photooximation technique in 1952, and onwards. This photooximation reaction uses the gases nitric oxide and chlorine. By the addition of hydrogen chloride in the presence of a catalyst and a mercury high pressure lamp we were able to obtain the desired cyclohexanone-oxime directly from cyclohexane1 4.