The reciprocal effect of positioning the base makes it impossible to get the target product. Ortho-para substituents are always stronger than meta substituents.

Localization law of binary substituted benzene

When there are two substituents on the benzene ring, the position of the third substituent entering the benzene ring depends on the positioning of the original two substituents.

The two positioning groups do not belong to the same class, and the positioning effect on the third substituent is inconsistent. The position where the third substituent enters the benzene ring is mainly located by the first positioning group.

Fundamentals of Chemical Localization of Baidu Library Page 6-7

/view/5e4e 90 18a 76 e 58 fafab 003 b 9 . html

So how should this experiment be designed?

Experimental design:

Nitration → nitrobenzene

—Reduction → Aniline

—acylation → acetanilide

-nitration → p-nitroacetanilide

—Bromine →4- nitro-2,6-dichloroacetanilide

-Hydrolysis →4- nitro-2,6-dichloroaniline

-nitrosation →4- nitro-2,6-dichlorobenzene diazonium salt

-Nitrogen removal from phosphorous acid → 3,5-dibromonitrobenzene