| 摘要 |
Process for preparing 6-chloro-(6H)-dibenz[c,e][1,2]oxaphosphorin of the formula (I), <IMAGE> (I) in which R1 and R2 are identical or different and are halogen, alkyl or alkoxy, each having from 1 to 6 carbon atoms, and a and b are integers from 0 to 3, preferably from 0 to 2, by reaction of o-phenylphenol of the formula (II), <IMAGE> (II) in which R1, R2, a and b are as defined above, with phosphorus trichloride in the presence of Lewis acids as catalysts with elimination of hydrogen chloride, wherein the phosphorus trichloride is metered into the mixture of compound (II) and Lewis acid at temperatures of 170 DEG -220 DEG C.
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