PURPOSE: To obtain a benzophenone derivative high in purity and discolored little compared to the case with the single oxidation process using chloranil, without the need of any repurification process.
CONSTITUTION: This benzophenone derivative of formula II is obtained by oxidation of a diphenyl derivative of formula I (R2-R4 are each H or a 1-4C alkyl; X1 and X2 are each a 1-4C alkyl, 1-4C alkoxyl or halogen) with a mixed oxidizing agent composed of chloranil (at 0.1-0.5, pref. 0.2-0.3, molar times the diphenyl derivative) and sodium chlorite (at 0.5-1.5, pref. 0.8-1.0, molar times the diphenyl derivative) at 30-100 (pref. 50-60)°C. Combined use of the chloranil and sodium chlorite can significantly reduce the use of the chloranil to 1/10 the case with the single oxidation process, resulting in no crystal deposition of hydroquinone form, omitting filtration process, and facilitating the separation of the oxidizing agent from the final product.
KIMURA IKUO
YASUMURA MASATERU
