| 摘要 |
<p>PURPOSE:To obtain a racemic dihalovinylcyclopropanecarboxylic acid halide (hereinafter referred to as dihalo-acid halide), rich in the trans-isomer of low toxicity and useful as a synthetic intermediate for insecticides in good yield without requiring a special apparatus by reacting an optically active dihalo-acid halide with boron iodide and racemizing the dihalo-acid halide. CONSTITUTION:An optically active dihalo-acid halide expressed by the formula (X and Y are halogen; * indicates asymmetric carbon) is reacted with boron iodide (e.g. boron triiodide) in a solvent, such as chlorobenzene, at 40-150 deg.C to afford a racemized dihalo-acid halide. The boron iodide is used in a molar amount of (1/200)-1 based on the dihalo-acid halide.</p> |
