Dolbier HW Solutions 549

Dolbier HW Solutions 549 - Replace amino group by bromine:...

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Fluorobenzene is prepared from aniline by the Schiemann reaction, shown in Section 22.18. Aniline is, of course, prepared from benzene via nitrobenzene. Friedel Crafts acylation of f uorobenzene has been carried out with the results shown and gives the required ethyl p - f uorophenyl ketone as the major product. ( c ) Our synthetic plan is based on the essential step of forming the f uorine derivative from an amine by way of a diazonium salt. The required substituted aniline is derived from m -xylene by a standard synthetic sequence. ( d ) In this problem two nitrogen-containing groups of the starting material are each to be replaced by a halogen substituent. The task is suf F ciently straightforward that it may be confronted directly.
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Unformatted text preview: Replace amino group by bromine: NH 2 NO 2 CH 3 2-Methyl-4-nitro-1-naphthylamine Br NO 2 CH 3 1-Bromo-2-methyl-4-nitronaphthalene (82%) 1. NaNO 2 , HBr, H 2 O 2. CuBr Br 2 H 3 C CH 3 m-Xylene NO 2 H 3 C CH 3 1,3-Dimethyl-4-nitrobenzene (98%) NH 2 H 3 C CH 3 2,4-Dimethylaniline HNO 3 H 2 SO 4 1. Fe, HCl 2. HO 2 Br F H 3 C CH 3 1-Bromo-2-f uoro-3,5-dimethylbenzene (60%) 2-Bromo-4,6-dimethylaniline Br NH 2 H 3 C CH 3 1. NaNO 2 , HCl, H 2 O, 0 8 C 2. HBF 4 3. heat Br F H 3 C CH 3 1-Bromo-2-f uoro-3,5-dimethylbenzene Br NH 2 H 3 C CH 3 NH 2 H 3 C CH 3 2,4-Dimethylaniline 1 F CCH 2 CH 3 O Ethyl p-f uorophenyl ketone (86%) F Fluorobenzene Propanoyl chloride CH 3 CH 2 CCl O AlCl 3 AMINES 643...
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