Cycloaliphatic urea derivatives

The research laboratories of the BASF and the Bayer Corporations in Europe and the Hercules in the USA were active in the development of this family of compounds. 

The weed-killing properties of cycluron, 3-cyclooctyl-1,1-dimethylurea (2) were first reported by Fischer (1960). 

It was developed as an experimental herbicide in 1958 by the BASF. Relationships between the structure and biological activity of cycloaliphatic urea derivatives were summarised first by Scheurer and Fischer (1962).Three routes are described in the patent literature for the synthesis of cycluron (Fischer et al 1958 Fischer, 1959 Steinbrunn and Fischer 1959). 

The acute oral of cycluron for rats is 2600 mg/kg, for mice 300 mg/kg. It does 

It is effective mainly for the control of monocotyledonous germinating annual weeds as a preemergence herbicide at rates of 0.8-2 kg/ha. Its effect is unsatisfactory in dry weather. Its action lasts for over one growing season. 

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Urea herbicides with cycloaliphatic substituents may contain several kinds of cycloalkyl and cycloalkenyl radicals, but only those in which two methyl groups are the substituents on N 1 are of satisfactory activity. A longer alkyl chain reduces herbicidal efficiency, this is also true for aryl urea derivatives. 

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