Friedrich Karrer

Short synthesis of 4-chloro-4′-(chlorodifluoromethoxy)benzophenone

Abstract A one-pot, highly selective synthesis of 4-chloro-4′-(chlorodifluoromethoxy)benzophenone suitable for an industrial scale-up was developed. Fluorination of 4-(trichloromethoxy)benzoyl chloride at –20°C with HF to 4-(chlorodifluoromethoxy)benzoyl fluoride followed by an in situ Friedel–Crafts reaction with chlorobenzene in the presence of BF 3 at –5°C yielded the title compound in excellent yield.

Synthesis and structure-activity relationships of benzophenone hydrazone derivatives with insecticidal activity.

A broad range of benzophenone hydrazone derivatives was prepared and tested against selected chewing insect pests, allowing the analysis of structure-activity relationships. Good activity was found only when the aromatic rings were substituted at the 4-positions with an halogen atom and a triflate or perhaloalkoxy group. In contrast, a number of substituents on the hydrazone part led to active compounds, the best results being achieved with acyl-type substituents. The excellent laboratory and greenhouse activity of the best representatives was confirmed in semi-field trials against Spodoptera littoralis.

Synthesis and insecticidal activity of 4-perhaloalkoxy (or thioalkyl) benzophenonehydrazone derivatives†

Benzophenonehydrazone derivatives containing a mesylate or triflate substituent are known to exhibit insecticidal activity. In the present study, such substituents have been replaced by perhaloalkoxy groups. High levels of activity against lepidopteran pests were observed in greenhouse trials. For optimum activity, the substituents should be relatively small. In semi-field trials, however, none of the compounds tested showed sufficient persistence to warrant further development.