Method for the preparation of 2,2,3,3-tetrachloro-2,3-dihydro-1,4-benzodioxines, and the compound 6-isocyanato-2,2,3,3-tetrachloro-2,3-dihydro-1,4-benzodioxine

摘要

1. Process for the preparation of 2,2,3,3-tetrachloro-1,4-benzodioxenes of the formula see diagramm : EP0156195,P5,F1 in which R1 and R2 independently of one another represent H, Cl, F, CF3 , CCl3 , COCl, CN, OCOCF3 , OCOCCl3 , OCOCF2 Cl, OCOCl, OCOF, NCO, phenyl or phenyl which is substituted by one or more of the above radicals, characterized in that one or more compounds of the formula see diagramm : EP0156195,P5,F2 in which R3 and R4 independently of one another represent H, Cl, F, CF3 , CCl3 , COCl, CN, OCOCF3 , OCOCCl3 , OCOCF2 Cl, OCOCl, OCOF, NCO, CHO, CH3 , phenyl or phenyl which is substituted by one or more of the above radicals and A represents CH2 -CH2 , CHCl-CH2 , CCl2 -CH2 , CHCl-CHCl, CCl2 -CHCl, CH=CH, CCl=CH or CCl=CCl, are reacted with chlorine in the presence of an agent which forms free radicals.